Method for manufacturing nitride semiconductor light emitting element and nitride semiconductor light emitting element

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a method for manufacturing a nitride semiconductor light emitting device and a nitride semiconductor light emitting device, and more particularly to a method for manufacturing a nitride semiconductor light emitting device including a nitride semiconductor layer and a nitride semiconductor light emitting device.

【0002】

[Conventional technology]

In recent years, nitride-based semiconductor light-emitting devices are expected to be used as light sources for next-generation large-capacity disks, and their development is being actively carried out.

【0003】

FIG. 32 is a cross-sectional view showing a conventional nitride-based semiconductor light emitting device (nitride-based semiconductor laser device).

【0004】

First, the structure of a conventional nitride-based semiconductor laser device will be described with reference to FIG. 32. In this conventional nitride-based semiconductor laser device, as shown in FIG. 32, an AlGaN low-temperature buffer layer 102 having a thickness of about 15 nm is formed on the sapphire substrate 101. On the AlGaN low temperature buffer layer 102, an undoped GaN layer 103 having a thickness of about 3 μm, an n-type GaN contact layer 104 having a thickness of about 5 μm, an n-type AlGaN clad layer 105 having a thickness of about 1 μm, and about 50 nm. An MQW (Multiple Quantum Well) light emitting layer 106 made of AlGaN / InGaN having a thickness and a p-type AlGaN clad layer 107 having a thickness of about 300 nm and including a convex portion are formed in this order. A p-type GaN contact layer 108 having a thickness of about 70 nm is formed on the convex portion of the p-type AlGaN clad layer 107. The convex portion of the p-type AlGaN clad layer 107 and the p-type GaN contact layer 108 form a striped ridge portion.

【0005】

A TiO that covers a region other than the upper surface of the p-type GaN contact layer 108 and has an opening on the upper surface of the n-type contact layer 104.₂Layer 109 is formed. Further, the p-side electrode 110 is formed so as to come into contact with the upper surface of the p-type GaN contact layer 108. Further, the p-side pad electrode 111 is formed so as to come into contact with the upper surface of the p-side electrode 110.

【0006】

In addition, a part of the region from the p-type AlGaN clad layer 107 to the n-type GaN contact layer 104 has been removed. And TiO₂The n-side electrode 112 is formed so as to contact the upper surface of the n-type GaN contact layer 104 exposed by the opening of the layer 109. Further, the n-side pad electrode 113 is formed so as to come into contact with the n-side electrode 112.

【0007】

33 to 38 are cross-sectional views for explaining the manufacturing process of the conventional nitride-based semiconductor laser device shown in FIG. 32. Next, the manufacturing process of the conventional nitride-based semiconductor laser device will be described with reference to FIGS. 32 to 38.

【0008】

First, as shown in FIG. 33, using the MOCVD method, the AlGaN low temperature buffer layer 102 was placed on the sapphire substrate 101 at a low temperature of about 15 nm under a temperature condition of about 600 ° C to alleviate lattice mismatch. Grow. Further, the MOCVD method is used to form an undoped GaN layer 103 having a thickness of about 3 μm on the AlGaN low temperature buffer layer 102. Then, using the MOCVD method, from the n-type GaN contact layer 104 having a thickness of about 5 μm, the n-type AlGaN clad layer 105 having a thickness of about 1 μm, and AlGaN / InGaN having a thickness of about 50 nm on the undoped GaN layer 103. The MQW light emitting layer 106, the p-type AlGaN clad layer 107 having a thickness of about 300 nm, and the p-type GaN contact layer 108 having a thickness of about 70 nm are sequentially formed. Then, by performing a heat treatment for 30 minutes in a nitrogen atmosphere at about 800 ° C., p-type impurities such as Mg in the p-type AlGaN clad layer 107 and the p-type GaN contact layer 108 are activated (conducting).

【0009】

Next, as shown in FIG. 34, the upper surface of the n-type GaN contact layer 104 is removed by removing a part of the n-type GaN contact layer 104 from the p-type GaN contact layer 108 by using anisotropic dry etching. Expose. After that, the substrate is washed with an acid and an organic solvent.

【0010】

Then, as shown in FIG. 35, a striped silicon oxide film (SiO) having a width of about 2 μm is formed in the region corresponding to the ridge portion on the p-type GaN contact layer 108.₂Membrane) 114 is formed. Using this silicon oxide film 114 as an etching mask, Cl₂The p-type GaN contact layer 108 is etched by anisotropic dry etching using gas, and the p-side AlGaN clad layer 107 is etched by a thickness of about 150 nm. As a result, a ridge portion as shown in FIG. 36 is formed.

【0011】

Next, as shown in FIG. 37, TiO is used on the entire surface by using an EB (Electron Beam) vapor deposition method.₂After forming layer 109, dilute hydrofluoric acid is used to place the silicon oxide film 114 on the TiO.₂Remove with layer 109. As a result, an opening is formed on the p-type GaN contact layer 108.

【0012】

Next, as shown in FIG. 38, the p-side electrode 110 is formed so as to cover the upper surface of the p-type GaN contact layer 108.

【0013】

Finally, as shown in FIG. 32, the p-side pad electrode 111 is formed so as to come into contact with the p-side electrode 110. In addition, TiO on the upper surface of the n-type GaN contact layer 104₂After removing part of the layer 109, the n-side electrode 112 is formed so as to contact the upper surface of the exposed n-type GaN contact layer 104. Further, the n-side pad electrode 113 is formed so as to come into contact with the upper surface of the n-side electrode 112. In this way, a conventional nitride-based semiconductor laser device is formed.

【0014】

[Problems to be Solved by the Invention]

In the conventional nitride-based semiconductor laser device, p-type impurities such as Mg in the p-type AlGaN clad layer 107 and the p-type GaN contact layer 108 are activated by performing a heat treatment at 700 ° C. or higher as described above. Was there. The reason why the heat treatment at a high temperature of 700 ° C. or higher is performed in this way is to remove hydrogen, which is incorporated during epitaxial growth and inhibits activation, from the semiconductor. However, when the heat treatment is performed at a high temperature of 700 ° C. or higher, the nitrogen atoms that are the components of the nitride semiconductor layer are easily dissociated, so that the p-type AlGaN clad layer 107 and the p-type GaN contact layer 108 are crystalline. Has the inconvenience of being easily deteriorated. Therefore, the carrier concentration (concentration of activated p-type impurities in the nitride semiconductor) in the p-type AlGaN clad layer 107 and the p-type GaN contact layer 108 decreases, and it is difficult to obtain a sufficient carrier concentration. Is. As described above, when the carrier concentration decreases, the resistivity of the p-type AlGaN clad layer 107 and the p-type GaN contact layer 108 and the contact resistance with the p-side electrode 110 increase. As a result, the operating voltage of the element becomes high, so that there is a problem that the power consumption increases. Further, there is also a problem that the amount of heat generated increases due to the increase in power consumption, and as a result, the life of the element is shortened.

【0015】

The present invention has been made to solve the above-mentioned problems, and one object of the present invention is that impurities in the nitride semiconductor layer can be sufficiently activated even by low-temperature heat treatment. The present invention provides a method for manufacturing a nitride semiconductor light emitting device.

【0016】

Another object of the present invention is to provide a nitride semiconductor light emitting device capable of sufficiently activating impurities in the nitride semiconductor layer even by low temperature heat treatment.

【0017】

Yet another object of the present invention is to improve the luminous efficiency with respect to an electric current in the above-mentioned nitride semiconductor light emitting device.

【0018】

[Means for solving problems]

The method for manufacturing a nitride semiconductor light emitting device according to the first aspect of the present invention includes a step of forming a nitride semiconductor layer containing a first conductive type impurity on the active layer and a method of forming the nitride semiconductor layer on the nitride semiconductor layer. A step of forming the first electrode layer and then a step of activating the first conductive type impurities in the nitride semiconductor layer by heat treatment at 600 ° C. or lower are provided.

【0019】

In the method for manufacturing a nitride-based semiconductor light-emitting device according to the first aspect, as described above, the first electrode layer is formed on the nitride-based semiconductor layer and then heat-treated at 600 ° C. or lower to obtain a nitride-based semiconductor. By activating the first conductive type impurities in the semiconductor layer, the hydrogen desorption energy on the surface of the nitride semiconductor layer is reduced by the first electrode layer, so that the hydrogen that inhibits the activation of the impurities is cooled at a low temperature. Can be removed efficiently. Further, since the heat treatment can be performed at a low temperature of 600 ° C. or lower, dissociation of nitrogen, which is a constituent atom of the nitride semiconductor layer, can be prevented. As a result, it is possible to prevent the crystallinity of the nitride-based semiconductor layer from deteriorating, so that impurities can be satisfactorily activated, and as a result, the carrier concentration can be increased. As a result, the resistivity of the nitride semiconductor layer and the contact resistance with the first electrode layer can be reduced, so that the operating voltage of the device can be reduced. Therefore, since the power consumption of the element can be reduced, the amount of heat generated can be reduced, and as a result, the life of the element can be improved. Further, by using the first electrode layer as it is as an electrode of the nitride semiconductor light emitting device, it is possible to prevent contamination of the surface of the nitride semiconductor layer after heat treatment and reduction of impurities on the surface of the nitride semiconductor layer. Therefore, the contact resistance of the electrode can be further reduced. Further, since the heat treatment for activating impurities can also serve as the heat treatment for reducing the contact resistance between the first electrode layer and the nitride semiconductor layer, the manufacturing process can be simplified.

【0020】

In the method for manufacturing a nitride semiconductor light emitting device according to the first aspect, the first electrode layer preferably has a film thickness of 50 nm or less. With this configuration, the hydrogen desorption energy on the surface of the nitride semiconductor layer can be easily reduced by the first electrode layer having a small film thickness of 50 nm or less.

【0021】

In the above method for manufacturing a nitride semiconductor light emitting device, the first electrode layer preferably includes at least one of a Pd layer, a Ni layer and a Pt layer. If the first electrode layer is formed of such a metal material, the hydrogen desorption energy on the surface of the nitride semiconductor layer can be easily reduced, so that hydrogen that inhibits the activation of impurities can be efficiently produced at a low temperature. Can be removed well. Thereby, impurities can be easily activated at a low temperature.

【0022】

In the above method for manufacturing a nitride semiconductor light emitting device, preferably, the step of forming the nitride semiconductor layer includes a step of forming a nitride semiconductor layer having a concave-convex surface. With this configuration, the surface area of the nitride semiconductor layer can be increased due to the uneven surface, so that the contact area between the nitride semiconductor layer and the first electrode layer can be increased. As a result, the area where hydrogen is desorbed increases, so that the heat treatment time can be shortened, and as a result, the process time can be shortened. Further, since the surface area of the nitride semiconductor layer can be increased by the uneven surface, the contact resistance can be reduced and the adhesiveness between the nitride semiconductor layer and the first electrode layer can be improved. Can be done.

【0023】

The above-mentioned method for manufacturing a nitride semiconductor light emitting device preferably further includes a step of forming an insulating film on the first electrode layer prior to the step of heat treatment. With this configuration, semiconductor elements such as Ga constituting the nitride semiconductor are diffused to the outside toward the insulating film, so that impurities easily enter the depleted Ga site. Thereby, the carrier concentration can be further increased.

【0024】

The nitride-based semiconductor light emitting element according to the second aspect of the present invention includes a nitride-based semiconductor layer formed on the active layer, a first electrode layer formed on a part of the nitride-based semiconductor layer, and nitrided. A first conductive type region formed so as to reach the active layer is provided in a portion of the physical semiconductor layer located in the region below the first electrode layer.

【0025】

In the nitride semiconductor light emitting device according to the second aspect of the present invention, since the current flows only in the region below the first electrode layer, the current loss due to weak light emission or leakage due to the current flowing in the unnecessary portion occurs. It can be suppressed from occurring. Thereby, the luminous efficiency with respect to the current can be improved. Further, when activating impurities in the portion located in the lower region of the first electrode layer, if the first electrode layer is formed and then heat-treated, the first electrode layer can be used to form a nitride semiconductor layer. Since the hydrogen desorption energy on the surface is reduced, hydrogen that inhibits the activation of impurities can be efficiently removed at a low temperature. As a result, impurities can be activated by low-temperature heat treatment, so that the carrier concentration can be increased. As a result, the resistivity of the nitride semiconductor layer and the contact resistance with the first electrode layer can be reduced, so that the operating voltage of the device can be reduced. Therefore, since the power consumption of the element can be reduced, the amount of heat generated can be reduced, and as a result, the life of the element can be improved.

【0026】

In the method for manufacturing a nitride semiconductor light emitting device according to the first aspect, a step of forming a second electrode layer in a predetermined region on the first electrode layer after the heat treatment may be further provided. With this configuration, an electrode composed of the first electrode layer and the second electrode layer can be easily formed. In this case, the second electrode layer may be used as a mask to further include a step of etching the first electrode layer. With this configuration, the first electrode layer can be easily patterned in the same shape as the second electrode layer.

【0027】

Further, in the above method for manufacturing a nitride semiconductor light emitting device, a step of forming a ridge portion may be further provided by etching the nitride semiconductor layer with the second electrode layer as a mask. With this configuration, the ridge portion can be formed without separately providing an etching mask.

【0028】

Further, in the method for manufacturing a nitride semiconductor light emitting device including the step of forming a nitride semiconductor layer having a concave-convex surface, the nitride semiconductor layer having a concave-convex surface has an In of 3% or more. It may have a composition. With this configuration, the surface of the nitride semiconductor layer can be easily formed into an uneven shape. Further, in this case, the step of forming the nitride semiconductor layer having the uneven surface is the step of forming the nitride semiconductor layer having the uneven surface by etching the surface of the nitride semiconductor layer. May include. Even with such a configuration, the surface of the nitride semiconductor layer can be easily formed into an uneven shape.

【0029】

Further, in the above method for manufacturing a nitride semiconductor light emitting device, the step of activating the first conductive type impurities by heat treatment is N.₂, Ar, He, N₂O, O₂And may include the step of performing the heat treatment in any one atmosphere of vacuum. With this configuration, since hydrogen is not contained in the atmosphere, hydrogen that inhibits the activation of impurities can be efficiently removed at a low temperature.

【0030】

Further, in the above method for manufacturing a nitride semiconductor light emitting element, the step of forming the first electrode layer includes a step of forming the first electrode layer on a part of the nitride semiconductor layer, and heat treatment is performed. The step of activating the first conductive type impurities by means of the above may include a step of activating only the first conductive type impurities located in the region below the first electrode layer by heat treatment. With this configuration, since the current flows only in the region below the first electrode layer, it is possible to suppress the occurrence of current loss due to weak light emission or leakage due to the current flowing in the unnecessary portion. .. Thereby, the luminous efficiency with respect to the current can be improved.

【0031】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

【0032】

(First Embodiment) FIG. 1 is a cross-sectional view showing a nitride-based semiconductor light emitting device (nitride-based semiconductor laser device) according to the first embodiment of the present invention.

【0033】

First, the structure of the nitride-based semiconductor laser device of the first embodiment will be described with reference to FIG. In this first embodiment, as shown in FIG. 1, an AlGaN low temperature buffer layer 2 having a thickness of about 15 nm is formed on the sapphire substrate 1. An undoped GaN layer 3 having a thickness of about 3 μm is formed on the AlGaN low temperature buffer layer 2. On the undoped GaN layer 3, an MQW light emitting layer 6 composed of an n-type GaN contact layer 4 having a thickness of about 5 μm, an n-type AlGaN clad layer 5 having a thickness of about 1 μm, and AlGaN / InGaN having a thickness of about 50 nm. , And a p-type AlGaN clad layer 7 having a thickness of about 300 nm and including a convex portion is formed in this order. A p-type GaN contact layer 8 having a thickness of about 70 nm is formed on the convex portion of the p-type AlGaN clad layer 7. The ridge portion is formed by the convex portion of the p-type AlGaN clad layer 7 and the p-type GaN contact layer 8.

【0034】

Here, in the first embodiment, the Pd electrode layer 9 having a thickness of about 2 nm is formed on the p-type GaN contact layer 8. Further, on the Pd electrode layer 9, a metal film 10 composed of a laminated film of a Pd layer having a thickness of about 10 nm, an Au layer having a thickness of about 100 nm, and a Ni layer having a thickness of about 200 nm is formed. There is. The p-side electrode is composed of the Pd electrode layer 9 and the metal film 10. The p-type AlGaN clad layer 7 and the p-type GaN contact layer 8 are examples of the "nitride-based semiconductor layer containing first conductive type impurities" of the present invention. The Pd electrode layer 9 is an example of the "first electrode layer" of the present invention.

【0035】

Further, a silicon oxide film (SiO) that covers a region other than the upper surface of the metal film 10 and has an opening on the upper surface of the n-type GaN contact layer 4.₂Membrane) 11 is formed. Further, the p-side pad electrode 12 is formed so as to come into contact with the upper surface of the metal film 10. Then, the n-side electrode 13 is formed so as to come into contact with the upper surface of the n-type GaN contact layer 4 exposed by the opening of the silicon oxide film 11. Further, the n-side pad electrode 14 is formed so as to come into contact with the upper surface of the n-side electrode 13.

【0036】

2 to 7 are cross-sectional views for explaining a manufacturing process of a nitride-based semiconductor light emitting device (nitride-based semiconductor laser device) according to the first embodiment shown in FIG. Next, the manufacturing process of the nitride-based semiconductor laser device according to the first embodiment will be described with reference to FIGS. 1 to 7.

【0037】

First, as shown in FIG. 2, using the MOCVD method, the AlGaN low temperature buffer layer 2 was placed on the sapphire substrate 1 at a low temperature of about 15 nm under a temperature condition of about 600 ° C to alleviate lattice mismatch. Grow. Further, the MOCVD method is used to form an undoped GaN layer 3 having a thickness of about 3 μm on the AlGaN low temperature buffer layer 2. Then, using the MOCVD method, an n-type GaN contact layer 4 having a thickness of about 5 μm, an n-type AlGaN clad layer 5 having a thickness of about 1 μm, and an AlGaN / InGaN having a thickness of about 50 nm are placed on the undoped GaN layer 3. An MQW light emitting layer 6 composed of the MQW light emitting layer 6, a p-type AlGaN clad layer 7 having a thickness of about 300 nm, and a p-type GaN contact layer 8 having a thickness of about 70 nm are sequentially formed.

【0038】

Next, as shown in FIG. 3, a part of the n-type GaN contact layer 4 is removed by removing a part of the n-type GaN contact layer 4 from the p-type GaN contact layer 8 by using anisotropic dry etching. Expose the area. After that, the substrate is washed with an acid and an organic solvent.

【0039】

Next, in this first embodiment, as shown in FIG. 4, a Pd layer 9a having a thickness of about 2 nm is formed on the entire surface by using the EB vapor deposition method. Then, heat treatment for 10 minutes in a nitrogen atmosphere at about 300 ° C. activates p-type impurities such as Mg contained in the p-type AlGaN clad layer 7 and the p-type GaN contact layer 8.

【0040】

Next, as shown in FIG. 5, the lift-off method was used to obtain a Pd layer having a thickness of about 10 nm and an Au layer having a thickness of about 100 nm in the region corresponding to the ridge portion on the Pd layer 9a. A striped metal film 10 having a width of about 2 μm is formed, which is composed of a laminated film with a Ni layer having a thickness of 200 nm. Then, using the uppermost Ni layer of the metal film 10 as an etching mask, CF₄The Pd layer 9a and the p-type GaN contact layer 8 are etched by anisotropic dry etching using gas, and the p-type AlGaN clad layer 7 is etched by a thickness of about 150 nm. As a result, a ridge portion as shown in FIG. 6 is formed. In this way, the p-side electrode composed of the metal film 10 and the Pd electrode layer 9 is formed.

【0041】

Next, as shown in FIG. 7, a silicon oxide film 11 is formed on the entire surface by using a plasma CVD method, and then an opening is formed on a part of the n-type GaN contact layer 4. After that, the n-side electrode 13 is formed in the opening of the silicon oxide film 11 so as to come into contact with the upper surface of the n-type GaN contact layer 4.

【0042】

Finally, as shown in FIG. 1, after removing the silicon oxide film 11 on the upper surface of the metal film 10, the p-side pad electrode 12 is formed so as to come into contact with the upper surface of the metal film 10. Further, the n-side pad electrode 14 is formed so as to come into contact with the n-side electrode 13. In this way, the nitride-based semiconductor laser device of the first embodiment is formed.

【0043】

In the manufacturing process of the nitride semiconductor laser device of the first embodiment, as described above, the surface of the nitride semiconductor layer (p-type AlGaN clad layer 7 and p-type GaN contact layer 8) has a thickness of about 2 nm. After forming the Pd layer 9a, the p-type impurities such as Mg in the p-type AlGaN clad layer 7 and the p-type GaN contact layer 8 are activated by heat treatment at a low temperature (about 300 ° C) of 600 ° C or less. As a result, the Pd layer 9a reduces the hydrogen desorption energy on the surfaces of the p-type AlGaN cladding layer 7 and the p-type GaN contact layer 8, so that hydrogen that inhibits the activation of p-type impurities is efficiently removed at low temperature. be able to.

【0044】

Further, in the first embodiment, since the heat treatment can be performed at a low temperature (about 300 ° C) of 600 ° C or less, the dissociation of nitrogen, which is a component of the p-type AlGaN clad layer 7 and the p-type GaN contact layer 8, can be dissociated. Can be prevented. As a result, it is possible to prevent the crystallinity of the p-type AlGaN clad layer 7 and the p-type GaN contact layer 8 from deteriorating, so that p-type impurities such as Mg can be satisfactorily activated. As a result, the carrier concentration (activation rate) of p-type impurities can be increased. As a result, the resistivity of the p-type AlGaN clad layer 7 and the p-type GaN contact layer 8 and the contact resistance with the Pd electrode layer 9 can be reduced, so that the operating voltage of the device can be reduced. Therefore, since the power consumption of the element can be reduced, the amount of heat generated can be reduced, and as a result, the life of the element can be improved.

【0045】

As a result of confirmation by the inventors of the present application by experiments, the operating voltage of the nitride-based semiconductor laser device manufactured by using the conventional manufacturing process was about 7 V, whereas it is shown in the first embodiment. In the nitride-based semiconductor laser device manufactured using the manufacturing process, the operating voltage could be reduced to about 4.5V.

【0046】

By the way, the hydrogen desorption effect itself of the above-mentioned Pd membrane is already known. For example, 11p-Q-3 of the 62nd JSAP Academic Lecture Lecture Proceedings (2001.9. Aichi Institute of Technology) P257, etc. It is disclosed in. As a result of diligent studies focusing on the hydrogen desorption effect of this Pd film, the inventors of the present application have found that the Pd film is used as a part of the p-side electrode of the nitride-based semiconductor laser device as described above. It was. That is, the p-type AlGaN clad layer 7 and the p-type GaN contact layer are formed by forming the Pd layer 9a, which is a part of the p-side electrode, on the surface of the p-type GaN contact layer 8 and then heat-treating at about 300 ° C. We have found a manufacturing process that activates 8 p-type impurities. In this way, by using the Pd layer 9a as it is as a part of the p-side electrode even after the heat treatment is completed, the surface of the p-type GaN contact layer 8 is protected by the Pd layer 9a in the subsequent manufacturing process, so that the heat treatment is performed. It is possible to prevent the surface contamination of the p-type GaN contact layer 8 and the decrease of carriers on the surface of the p-type GaN contact layer 8 later. As a result, it is possible to reduce the contact resistance of the p-side electrode. Further, the heat treatment for activating the p-type AlGaN clad layer 7 and the p-type GaN contact layer 8 can be combined with the heat treatment for reducing the contact resistance of the p-side electrode, thus simplifying the manufacturing process. It becomes possible.

【0047】

Furthermore, the inventors of the present application have found that the degree of activation changes depending on the film thickness of the Pd film. To confirm this point, the following experiment was conducted. After forming a Pd film on the nitride semiconductor layer, p-type impurities in the nitride semiconductor layer were activated by heat treatment at about 400 ° C. Then, the relationship between the film thickness of the Pd film in this case and the resistivity of the nitride semiconductor layer after the heat treatment was measured. The results are shown in Figure 8.

【0048】

As shown in FIG. 8, when the film thickness of the Pd film on the nitride semiconductor layer is set to about 50 nm or more, the resistivity is high and the nitride semiconductor layer is activated (conducting) by heat treatment at about 400 ° C. ) Turns out to be difficult. On the other hand, when the film thickness of the Pd film is set to about 50 nm or less, it can be seen that the resistivity can be reduced by performing a heat treatment at about 400 ° C. From this, it was clarified that the nitride semiconductor layer can be activated at about 400 ° C. when the film thickness of the Pd film is set to about 50 nm or less.

【0049】

(Second Embodiment) FIG. 9 is a cross-sectional view showing a nitride-based semiconductor light emitting device (nitride-based semiconductor laser device) according to the second embodiment of the present invention. Further, FIG. 10 is an enlarged cross-sectional view of the peripheral portion of the p-side electrode of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser device) of the second embodiment shown in FIG. In this second embodiment, unlike the first embodiment, an example in which a nitride semiconductor layer having a concave-convex surface is formed under the first electrode layer will be described. The other structures of the second embodiment are the same as those of the first embodiment.

【0050】

First, the structure of the nitride-based semiconductor laser device of the second embodiment will be described with reference to FIGS. 9 and 10. In the structure of the second embodiment, as shown in FIG. 9, an AlGaN low temperature buffer layer 2 having a thickness of about 15 nm is formed on the sapphire substrate 1 as in the first embodiment. An undoped GaN layer 3 having a thickness of about 3 μm is formed on the AlGaN low temperature buffer layer 2. On the undoped GaN layer 3, an MQW light emitting layer 6 composed of an n-type GaN contact layer 4 having a thickness of about 5 μm, an n-type AlGaN clad layer 5 having a thickness of about 1 μm, and AlGaN / InGaN having a thickness of about 50 nm. , And a p-type AlGaN clad layer 7 having a thickness of about 300 nm and including a convex portion is formed in this order. A p-type GaN contact layer 8 having a thickness of about 70 nm is formed on the convex portion of the p-type AlGaN clad layer 7. The ridge portion is formed by the convex portion of the p-type AlGaN clad layer 7 and the p-type GaN contact layer 8.

【0051】

Here, in the second embodiment, as shown in FIGS. 9 and 10, the p-type InGaN contact layer 21 having an In composition of about 15% and having a concavo-convex surface on the p-type GaN contact layer 8. Is formed with a thickness of about 3 nm. Further, on the p-type InGaN contact layer 21, a Pt / Pd electrode layer 29 composed of a Pt layer 29a having a thickness of about 1 nm in the lower layer and a Pd layer 29b having a thickness of about 1 nm in the upper layer is formed. .. Further, on the Pt / Pd electrode layer 29, a metal film 20 composed of a laminated film of a Pd layer having a thickness of about 10 nm, an Au layer having a thickness of about 100 nm, and a Ni layer having a thickness of about 200 nm is formed. Has been done. The p-side electrode is composed of the Pt / Pd electrode layer 29 and the metal film 20. The p-type InGaN contact layer 21 is an example of the "nitride semiconductor layer having an uneven surface" of the present invention, and the Pt / Pd electrode layer 29 is an example of the "first electrode layer" of the present invention. is there.

【0052】

Further, a silicon oxide film 11 having an opening is formed on the upper surface of the n-type GaN contact layer 4 while covering a region other than the upper surface of the metal film 20. Further, the p-side pad electrode 12 is formed so as to come into contact with the upper surface of the metal film 20. Then, the n-side electrode 13 is formed so as to come into contact with the upper surface of the n-type GaN contact layer 4 exposed by the opening of the silicon oxide film 11. Further, the n-side pad electrode 14 is formed so as to come into contact with the upper surface of the n-side electrode 13.

【0053】

In the nitride-based semiconductor laser device of the second embodiment, as described above, a p-type InGaN contact layer 21 having a concavo-convex surface is formed under the Pt / Pd electrode layer 29 to form a concavo-convex surface. Therefore, the contact area between the p-type InGaN contact layer 21 and the Pt / Pd electrode layer 29 can be increased. As a result, the area in which hydrogen can be desorbed to the outside in the nitride semiconductor layer increases during the heat treatment in the manufacturing process described later, so that the heat treatment time for activation can be shortened. As a result, the process time can be further shortened. Further, since the surface area of the p-type InGaN contact layer 21 can be increased by the uneven surface, the contact resistance can be reduced and the adhesion to the Pt / Pd electrode layer 29 can be improved.

【0054】

Further, in the nitride semiconductor laser device of the second embodiment, the Pt layer 29a having strong adhesion to the nitride semiconductor is formed between the Pd layer 29b and the p-type InGaN contact layer 21. The adhesion between the p-type InGaN contact layer 21 and the Pt / Pd electrode layer 29 can be further improved.

【0055】

11 to 16 are cross-sectional views for explaining a manufacturing process of a nitride-based semiconductor light emitting device (nitride-based semiconductor laser device) according to the second embodiment shown in FIGS. 9 and 10. Next, the manufacturing process of the nitride-based semiconductor laser device according to the second embodiment will be described with reference to FIGS. 9 to 16.

【0056】

First, as shown in FIG. 11, using the MOCVD method, the AlGaN low temperature buffer layer 2 was placed on the sapphire substrate 1 at a low temperature of about 15 nm under a temperature condition of about 600 ° C to alleviate lattice mismatch. Grow. Further, the MOCVD method is used to form an undoped GaN layer 3 having a thickness of about 3 μm on the AlGaN low temperature buffer layer 2. Then, using the MOCVD method, an n-type GaN contact layer 4 having a thickness of about 5 μm, an n-type AlGaN clad layer 5 having a thickness of about 1 μm, and an AlGaN / InGaN having a thickness of about 50 nm are placed on the undoped GaN layer 3. An MQW light emitting layer 6 composed of the MQW light emitting layer 6, a p-type AlGaN clad layer 7 having a thickness of about 300 nm, and a p-type GaN contact layer 8 having a thickness of about 70 nm are sequentially formed.

【0057】

Here, in the second embodiment, the p-type InGaN contact layer 21 having an In composition of 15% is formed on the p-type GaN contact layer 8. As shown in FIG. 10, the surface of the p-type InGaN contact layer 21 is formed into an uneven shape by containing about 15% of In.

【0058】

Next, as shown in FIG. 12, a part of the n-type GaN contact layer 4 is removed by removing a part of the n-type GaN contact layer 4 from the p-type InGaN contact layer 21 by using anisotropic dry etching. Expose the area. After that, the substrate is washed with an acid and an organic solvent.

【0059】

Next, in the second embodiment, as shown in FIG. 13, the Pt layer 29a having a thickness of about 1 nm in the lower layer and the Pd layer 29b having a thickness of about 1 nm in the upper layer are used on the entire surface by using the EB vapor deposition method. A Pt / Pd layer 9c composed of a laminated film with and is formed. Then, by performing a heat treatment for 10 minutes in a nitrogen atmosphere at about 300 ° C, p-type impurities such as Mg in the p-type InGaN contact layer 21, the p-type AlGaN clad layer 7, and the p-type GaN contact layer 8 are activated. To become.

【0060】

Next, as shown in FIG. 14, using the lift-off method, a Pd layer having a thickness of about 10 nm and an Au layer having a thickness of about 100 nm were formed in the region corresponding to the ridge portion on the Pt / Pd layer 29c. , A striped metal film 20 having a width of about 2 μm is formed, which is composed of a laminated film with a Ni layer having a thickness of about 200 nm. Then, using the uppermost Ni layer of the metal film 20 as an etching mask, CF₄The Pt / Pd layer 29c, the p-type GaN contact layer 8 and the p-type InGaN contact layer 21 are etched by anisotropic dry etching using gas, and the p-type AlGaN clad layer 7 has a thickness of about 150 nm. Only etch. As a result, a ridge portion as shown in FIG. 15 is formed. In this way, the p-side electrode composed of the metal film 20 and the Pt / Pd electrode layer 29 is configured.

【0061】

Next, as shown in FIG. 16, a silicon oxide film 11 is formed on the entire surface by using a plasma CVD method, and then an opening is formed on a part of the n-type GaN contact layer 4. After that, the n-side electrode 13 is formed in the opening of the silicon oxide film 11 so as to come into contact with the upper surface of the n-type GaN contact layer 4.

【0062】

Finally, as shown in FIG. 9, after removing the silicon oxide film 11 on the upper surface of the metal film 20, the p-side pad electrode 12 is formed so as to come into contact with the upper surface of the metal film 20. Further, the n-side pad electrode 14 is formed so as to come into contact with the n-side electrode 13. In this way, the nitride-based semiconductor laser device of the second embodiment is formed.

【0063】

As a result of confirmation by experiments, the operating voltage of the nitride semiconductor laser device manufactured by using the conventional manufacturing process was about 7V, whereas the manufacturing process shown in the second embodiment was used. In the produced nitride semiconductor light emitting device, the operating voltage could be reduced to about 4V.

【0064】

Other effects of the nitride-based semiconductor laser device of the second embodiment are the same as those of the first embodiment.

【0065】

(Third Embodiment) FIG. 17 is a cross-sectional view showing a nitride-based semiconductor light emitting device (nitride-based semiconductor laser device) according to the third embodiment of the present invention. Further, FIG. 18 shows a region in which p-type impurities are activated (conducting) in the nitride semiconductor layer of the nitride semiconductor light emitting device (nitride semiconductor laser device) of the third embodiment shown in FIG. It is an enlarged cross-sectional view which shows. In this third embodiment, unlike the first embodiment, an example in which only impurities in the nitride semiconductor layer in the region below the first electrode layer are activated will be described.

【0066】

First, the structure of the nitride-based semiconductor laser device of the third embodiment will be described with reference to FIGS. 17 and 18. In this third embodiment, as shown in FIG. 17, an AlGaN low temperature buffer layer 2 having a thickness of about 15 nm is formed on the sapphire substrate 1 as in the first embodiment. An undoped GaN layer 3 having a thickness of about 3 μm is formed on the AlGaN low temperature buffer layer 2. On the undoped GaN layer 3, an MQW consisting of an n-type GaN contact layer 4 having a thickness of about 5 μm, an n-type AlGaN clad layer 5 having a thickness of about 1 μm, and an AlGaN / InGaN superlattice layer having a thickness of about 50 nm. The light emitting layer 6 and the p-type AlGaN clad layer 37 having a thickness of about 300 nm and including a convex portion are formed in this order. A p-type GaN contact layer 38 having a thickness of about 70 nm is formed on the convex portion of the p-type AlGaN clad layer 37. The ridge portion is formed by the convex portion of the p-type AlGaN clad layer 37 and the p-type GaN contact layer 38.

【0067】

Here, in the third embodiment, the Pd electrode layer 39 having a thickness of about 1 nm is formed on the p-type GaN contact layer 38. Further, in the third embodiment, as shown in FIG. 18, among the p-type AlGaN clad layer 37 and the p-type GaN contact layer 38, the p-type impurities in the p-type activation region 32 located below the Pd electrode layer 39. Only are selectively activated (conducting). The p-type AlGaN clad layer 37 and the p-type GaN contact layer 38 are examples of the "nitride-based semiconductor layer containing first conductive type impurities" of the present invention. The Pd electrode layer 39 is an example of the "first electrode layer" of the present invention.

【0068】

Further, a silicon oxide film 11 having an opening is formed on the upper surface of the n-type GaN contact layer 4 while covering a region other than the upper surface of the Pd electrode layer 39. Then, the n-side electrode 13 is formed so as to come into contact with the upper surface of the n-type GaN contact layer 4 exposed by the opening of the silicon oxide film 11. Further, the n-side pad electrode 14 is formed so as to come into contact with the upper surface of the n-side electrode 13.

【0069】

In the nitride-based semiconductor laser device of the third embodiment, as described above, a current is applied to the device by selectively activating only the p-type impurities in the p-type activation region 32 below the Pd electrode layer 39. When applied, it is possible to suppress current loss due to weak light emission or leakage that occurs due to the current flowing into a region (non-light emitting region) other than the ridge portion of the element. This makes it possible to improve the luminous efficiency of the nitride-based semiconductor laser device with respect to the current applied to the device.

【0070】

Normally, in a nitride semiconductor laser device, the film thickness of the nitride semiconductor layer adjacent to the non-light emitting region of the device is strictly controlled in order to suppress the current loss due to weak light emission or leakage that occurs in the non-light emitting region. By (etching), the current (leakage current) flowing into the non-light emitting region of the device is suppressed. Therefore, in order to manufacture a nitride-based semiconductor laser device having good characteristics, extremely strict etching processing technology is required. On the other hand, in the nitride semiconductor laser device of the third embodiment described above, leakage current is suppressed by selectively activating (conducting) only the nitride semiconductor layer adjacent to the light emitting region of the device. can do. As a result, it is possible to suppress the current loss due to weak light emission or leakage generated in the non-light emitting region without strictly controlling (etching) the film thickness of the nitride semiconductor layer adjacent to the non-light emitting region of the device. Become.

【0071】

19 to 23 are cross-sectional views for explaining a manufacturing process of a nitride-based semiconductor light emitting device (nitride-based semiconductor laser device) according to the third embodiment shown in FIGS. 17 and 18. Next, the manufacturing process of the nitride-based semiconductor laser device according to the third embodiment will be described with reference to FIGS. 17 to 23.

【0072】

First, as shown in FIG. 19, in order to alleviate the lattice mismatch on the sapphire substrate 1 by using the MOCVD method, the AlGaN low temperature buffer layer 2 has a thickness of about 15 nm under a temperature condition of about 600 ° C. Grow at low temperature. Further, the MOCVD method is used to form an undoped GaN layer 3 having a thickness of about 3 μm on the AlGaN low temperature buffer layer 2. Then, using the MOCVD method, an n-type GaN contact layer 4 having a thickness of about 5 μm, an n-type AlGaN clad layer 5 having a thickness of about 1 μm, and an AlGaN / InGaN having a thickness of about 50 nm are placed on the undoped GaN layer 3. An MQW light emitting layer 6, a p-type AlGaN clad layer 37 having a thickness of about 300 nm, and a p-type GaN contact layer 38 having a thickness of about 70 nm are sequentially formed.

【0073】

Next, as shown in FIG. 20, a part of the n-type GaN contact layer 4 is removed by removing a part of the n-type GaN contact layer 4 from the p-type GaN contact layer 38 by using anisotropic dry etching. Expose the area. After that, the substrate is washed with an acid and an organic solvent.

【0074】

Next, in the third embodiment, as shown in FIG. 21, a Pd layer 39a having a thickness of about 1 nm is formed on the entire surface by using the EB vapor deposition method. Then, a striped insulating film 31 having a width of about 2 μm is formed in the region corresponding to the ridge portion on the Pd layer 39a.

【0075】

Next, as shown in FIG. 22, the Pd electrode layer 39 is formed by etching the Pd layer 39a by wet etching with nitric acid using the insulating film 31 as an etching mask. Further, using the insulating film 31 as an etching mask, BCl₃The p-type GaN contact layer 38 is etched by the RIE (Reactive Ion Etching) method using gas, and the p-type AlGaN clad layer 37 is etched by a thickness of about 150 nm.

【0076】

Here, in the third embodiment, as shown in FIG. 23, the p-type located below the Pd electrode layer 39 patterned by etching is performed by performing heat treatment for 10 minutes in a nitrogen atmosphere of about 300 ° C. Only p-type impurities in the activation region 32 are selectively activated.

【0077】

After that, a silicon oxide film 11 is formed on the entire surface by using a plasma CVD method, and then an opening is formed on a part of the n-type GaN contact layer 4. After that, the n-side electrode 13 is formed in the opening of the silicon oxide film 11 so as to come into contact with the upper surface of the n-type GaN contact layer 4. Further, the n-side pad electrode 14 is formed so as to come into contact with the n-side electrode 13.

【0078】

Finally, as shown in FIG. 17, after removing the silicon oxide film 11 on the upper surface of the Pd electrode layer 39, the p-side pad electrode 12 is formed so as to come into contact with the upper surface of the Pd electrode layer 39. In this way, the nitride-based semiconductor laser device of the third embodiment is formed.

【0079】

Other effects of the nitride-based semiconductor laser device of the third embodiment are the same as those of the first embodiment.

【0080】

(Fourth Embodiment) FIG. 24 is a cross-sectional view showing a nitride-based semiconductor light emitting device (nitride-based semiconductor LED element) according to the fourth embodiment of the present invention. Further, FIG. 25 shows a region in which p-type impurities are activated (conducting) in the nitride semiconductor layer of the nitride semiconductor light emitting device (nitride semiconductor LED element) of the fourth embodiment shown in FIG. 24. It is an enlarged sectional view which shows. In the fourth embodiment, unlike the first to third embodiments, an example in which the present invention is applied to a nitride semiconductor LED element is shown, and as in the third embodiment, the region under the first electrode layer is shown. An example in which only the p-type impurities in the nitride semiconductor layer are activated will be described.

【0081】

First, the structure of the nitride-based semiconductor LED element of the fourth embodiment will be described with reference to FIGS. 24 and 25. In this fourth embodiment, as shown in FIG. 24, an AlGaN low temperature buffer layer 2 having a thickness of about 15 nm is formed on the sapphire substrate 1. An undoped GaN layer 3 having a thickness of about 3 μm is formed on the AlGaN low temperature buffer layer 2. On the undoped GaN layer 3, an n-type GaN contact layer 4 having a thickness of about 5 μm, an MQW light emitting layer 6 made of AlGaN / InGaN having a thickness of about 50 nm, and a p-type AlGaN clad layer 47 having a thickness of about 100 nm. , And a p-type GaN contact layer 48 having a thickness of about 70 nm is formed in this order. The p-type AlGaN clad layer 47 and the p-type GaN contact layer 48 are examples of the "nitride-based semiconductor layer containing first conductive type impurities" of the present invention.

【0082】

Further, a silicon oxide film 11 having an opening is formed on the upper surface of the n-type GaN contact layer 4 while covering a region other than a part of the upper surface of the p-type GaN contact layer 48.

【0083】

Here, in the fourth embodiment, the Pd electrode layer 49 having a thickness of about 1 nm is formed so as to come into contact with the upper surface of the p-type GaN contact layer 48 exposed by the opening of the silicon oxide film 11. Further, in the fourth embodiment, as shown in FIG. 25, among the p-type AlGaN clad layer 47 and the Pd electrode layer 48, only the p-type impurities in the p-type activation region 42 located below the Pd electrode layer 49 are present. It is selectively activated.

【0084】

Further, the p-side pad electrode 51 is formed so as to come into contact with the upper surface of the Pd electrode layer 49. Further, the n-side electrode 13 is formed so as to come into contact with the upper surface of the n-type GaN contact layer 4 exposed by the opening of the silicon oxide film 11. Further, the n-side pad electrode 14 is formed so as to come into contact with the upper surface of the n-side electrode 13. The Pd electrode layer 49 is an example of the "first electrode layer" of the present invention.

【0085】

In the nitride-based semiconductor LED device of the fourth embodiment, when a current is applied to the device by selectively activating only the p-type impurities in the p-type activation region 42 under the Pd electrode layer 49. , It is possible to suppress the current loss due to weak light emission or leakage caused by the current flowing into the non-light emitting region of the element. This makes it possible to improve the luminous efficiency of the nitride-based semiconductor LED device with respect to the current applied to the device.

【0086】

26 to 30 are cross-sectional views for explaining the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor LED element) according to the fourth embodiment shown in FIGS. 24 and 25. Next, the manufacturing process of the nitride-based semiconductor LED element according to the fourth embodiment will be described with reference to FIGS. 24 to 30.

【0087】

First, as shown in FIG. 26, using the MOCVD method , the AlGaN low temperature buffer layer 2 was placed on the sapphire substrate 1 at a low temperature of about 15 nm under a temperature condition of about 600 ° C to alleviate lattice mismatch. Grow. Further, the MOCVD method is used to form an undoped GaN layer 3 having a thickness of about 3 μm on the AlGaN low temperature buffer layer 2. Then, using the MOCVD method, an n-type GaN contact layer 4 having a thickness of about 5 μm, an MQW light emitting layer 6 made of AlGaN / InGaN having a thickness of about 50 nm, and a thickness of about 100 nm are provided on the undoped GaN layer 3. A p-type AlGaN clad layer 47 and a p-type GaN contact layer 48 having a thickness of about 70 nm are sequentially formed.

【0088】

Next, as shown in FIG. 27, a part of the n-type GaN contact layer 4 is removed by removing a part of the n-type GaN contact layer 4 from the p-type GaN contact layer 48 by using anisotropic dry etching. Expose the area. Then, a silicon oxide film 11 having a thickness of about 200 nm is formed on the entire surface by a plasma CVD method, and then an opening is formed on a part of the p-type GaN contact layer 48. After that, the substrate is washed with an acid and an organic solvent.

【0089】

Next, as shown in FIG. 28, a Pd layer 49a having a thickness of about 1 nm is formed on the entire surface by using the EB vapor deposition method. Here, in the fourth embodiment, the p-type activation region 42 located below the Pd layer 49a in the opening of the silicon oxide film 11 by performing the heat treatment for 10 minutes in a nitrogen atmosphere of about 300 ° C. Selectively activates only the p-type impurities in.

【0090】

Next, as shown in FIG. 29, the lift-off method was used to increase the thickness of the lower layer of about 1 nm on the opening of the silicon oxide film 11 on the p-type GaN contact layer 48 so as to contact the Pd layer 49a. A p-side pad electrode 51 composed of a laminated film of a Pd layer having a Pd layer and an Au layer having a thickness of about 3 nm is formed. Next, the Pd electrode 49 is formed by etching the Pd layer 49a by wet etching with nitric acid using the Au layer above the p-side pad electrode 51 as an etching mask.

【0091】

Next, as shown in FIG. 30, after removing a part of the silicon oxide film 11 on the upper surface of the n-type GaN contact layer 4, the n-side electrode 13 is formed so as to contact the upper surface of the n-type GaN contact layer 4. To do.

【0092】

Finally, as shown in FIG. 24, the n-side pad electrode 14 is formed so as to come into contact with the n-side electrode 13. In this way, the nitride-based semiconductor LED element of the fourth embodiment is formed.

【0093】

In the manufacturing process of the nitride semiconductor LED element of the fourth embodiment, the following effects can be obtained as in the first to third embodiments.

【0094】

That is, in the manufacturing process of the nitride semiconductor LED element of the fourth embodiment, as described above, the thickness of about 1 nm is formed on the surface of the nitride semiconductor layer (p-type AlGaN clad layer 47 and p-type GaN contact layer 48). After forming the Pd layer 49a with, the p-type impurities such as Mg in the p-type AlGaN clad layer 47 and the p-type GaN contact layer 48 are activated by heat treatment at a low temperature (about 300 ° C) of 600 ° C or less. By doing so, the Pd layer 49a reduces the hydrogen desorption energy on the surfaces of the p-type AlGaN clad layer 47 and the p-type GaN contact layer 48, so that hydrogen that inhibits the activation of p-type impurities is efficiently removed. be able to.

【0095】

Further, in the manufacturing process of the nitride semiconductor LED element of the fourth embodiment, as described above, heat treatment can be performed at a low temperature (about 300 ° C) of 600 ° C or less, so that the p-type AlGaN clad layer 47 and It is possible to prevent the dissociation of nitrogen, which is a component of the p-type GaN contact layer 48. As a result, it is possible to prevent the crystallinity of the p-type AlGaN clad layer 47 and the p-type GaN contact layer 48 from deteriorating, so that p-type impurities such as Mg can be satisfactorily activated. As a result, the carrier concentration (activation rate) of p-type impurities can be increased. As a result, the resistivity of the p-type AlGaN clad layer 47 and the p-type GaN contact layer 48 and the contact resistance with the Pd electrode layer 49 can be reduced, so that the operating voltage of the device can be reduced. Therefore, since the power consumption of the element can be reduced, the amount of heat generated can be reduced, and as a result, the life of the element can be improved.

【0096】

Further, in the manufacturing process of the nitride semiconductor LED element of the fourth embodiment, as described above, the Pd layer 9a formed on the surface of the p-type GaN contact layer 48 before the heat treatment is directly used as the p-side electrode even after the heat treatment is completed. By using it as a part of, the surface of the p-type GaN contact layer 48 is protected by the Pd layer 9a in the subsequent manufacturing process, so that the surface contamination of the p-type GaN contact layer 48 after the heat treatment and the p-type GaN contact layer It is possible to prevent the loss of carriers on 48 surfaces. As a result, it is possible to reduce the contact resistance of the p-side electrode. Further, since the heat treatment for activating the p-type AlGaN clad layer 47 and the p-type GaN contact layer 48 and the heat treatment for reducing the contact resistance of the p-side electrode can be combined, the manufacturing process is simplified. be able to.

【0097】

It should be noted that the embodiments disclosed this time are examples in all respects and should not be considered to be restrictive. The scope of the present invention is shown by the scope of claims rather than the description of the above-described embodiment, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

【0098】

For example, in the above embodiment, a Pd electrode layer or a Pt / Pd electrode layer composed of a Pt / Pd laminated film is used as the first electrode layer on the p-type contact layer, but the present invention is not limited to this, and the Pd layer, Either one of the Ni layer and the Pt layer may be used. Further, the same effect can be obtained by using an alloy or a laminated film containing at least one of these.

【0099】

Further, in the first embodiment, in the step shown in FIG. 4, the p-type AlGaN clad layer 7 and the p-type GaN contact layer are formed by heat treatment with the Pd layer 9a formed on the p-type GaN contact layer 8. The p-type impurities in 8 were activated, but the present invention is not limited to this, and as shown in FIG. 31, heat treatment is performed in a state where an insulating film 60 made of a silicon oxide film is further formed on the Pd layer 9a. , The p-type impurities in the p-type AlGaN clad layer 7 and the p-type GaN contact layer 8 may be activated. With this configuration, during heat treatment, the insulating film 60 externally diffuses semiconductor elements such as Ga constituting the nitride semiconductor layer (p-type AlGaN clad layer 7 and p-type GaN contact layer 8). Is desorbed, which makes it easier for impurities to enter the depleted Ga site. As a result, the carrier concentration (activation rate) of impurities in the nitride-based semiconductor layer (p-type AlGaN clad layer 7 and p-type GaN contact layer 8) can be further increased.

【0100】

Further, in the above embodiment, nitrogen (N)₂) Heat treatment was performed to activate impurities in the nitride semiconductor layer in the atmosphere, but the present invention is not limited to this, and the present invention is not limited to this, and an inert gas such as Ar or He, N.₂O, O₂And the heat treatment may be performed in any atmosphere of vacuum. With this configuration, since hydrogen is not contained in the atmosphere during the heat treatment, hydrogen atoms having a function of inhibiting the activation of impurities in the nitride semiconductor layer can be efficiently removed.

【0101】

Further, in the second embodiment, an example is shown in which the surface of the nitride semiconductor layer is naturally formed into an uneven shape by setting the In composition of the nitride semiconductor layer to 15%. However, the In composition of the nitride semiconductor layer is shown. When is set to 3% or more, the surface of the nitride semiconductor layer can be similarly formed into an uneven shape. Further, the nitride semiconductor layer having an uneven surface may be formed by etching the surface of the nitride semiconductor layer.

【0102】

[Effect of the invention]

As described above, according to the present invention, it is possible to provide a method for manufacturing a nitride-based semiconductor device capable of sufficiently activating impurities in the nitride-based semiconductor layer even by low-temperature heat treatment.

[Simple explanation of drawings]

[Figure 1]

It is sectional drawing which showed the nitride-based semiconductor light emitting element (nitride-based semiconductor laser element) by 1st Embodiment of this invention.

[Figure 2]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 1st Embodiment shown in FIG.

[Fig. 3]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 1st Embodiment shown in FIG.

[Fig. 4]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 1st Embodiment shown in FIG.

[Fig. 5]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 1st Embodiment shown in FIG.

[Fig. 6]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 1st Embodiment shown in FIG.

[Fig. 7]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 1st Embodiment shown in FIG.

[Fig. 8]

It is a correlation diagram which showed the relationship between the film thickness of a Pd film and the resistivity of a nitride semiconductor layer.

[Fig. 9]

It is sectional drawing which showed the nitride-based semiconductor light emitting element (nitride-based semiconductor laser element) by 2nd Embodiment of this invention.

[Fig. 10]

FIG. 9 is an enlarged cross-sectional view of the periphery of the p-side electrode of the nitride semiconductor light emitting device (nitride semiconductor laser device) of the second embodiment shown in FIG.

[Fig. 11]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 2nd Embodiment shown in FIG. 9 and FIG.

[Fig. 12]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 2nd Embodiment shown in FIG. 9 and FIG.

[Fig. 13]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 2nd Embodiment shown in FIG. 9 and FIG.

[Fig. 14]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 2nd Embodiment shown in FIG. 9 and FIG.

[Fig. 15]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 2nd Embodiment shown in FIG. 9 and FIG.

[Fig. 16]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 2nd Embodiment shown in FIG. 9 and FIG.

[Fig. 17]

It is sectional drawing which showed the nitride-based semiconductor light emitting element (nitride-based semiconductor laser element) by 3rd Embodiment of this invention.

[Fig. 18]

FIG. 6 is an enlarged cross-sectional view showing a region in which p-type impurities are activated (conducting) in the nitride semiconductor layer of the nitride semiconductor light emitting device (nitride semiconductor laser device) of the third embodiment shown in FIG. ..

[Fig. 19]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 3rd Embodiment shown in FIG. 17 and FIG.

[Fig. 20]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 3rd Embodiment shown in FIG. 17 and FIG.

[Fig. 21]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 3rd Embodiment shown in FIG. 17 and FIG.

[Fig. 22]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 3rd Embodiment shown in FIG. 17 and FIG.

[Fig. 23]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by 3rd Embodiment shown in FIG. 17 and FIG.

[Fig. 24]

It is sectional drawing which showed the nitride-based semiconductor light-emitting element (nitride-based semiconductor LED element) including the nitride semiconductor layer according to 4th Embodiment of this invention.

[Fig. 25]

FIG. 6 is an enlarged cross-sectional view showing a region in which p-type impurities are activated (conducting) in the nitride semiconductor layer of the nitride semiconductor light emitting device (nitride semiconductor LED element) of the fourth embodiment shown in FIG. 24. ..

[Fig. 26]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor LED element) by 4th Embodiment shown in FIG. 24 and FIG.

[Fig. 27]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor LED element) by 4th Embodiment shown in FIG. 24 and FIG.

[Fig. 28]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor LED element) by 4th Embodiment shown in FIG. 24 and FIG.

[Fig. 29]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor LED element) by 4th Embodiment shown in FIG. 24 and FIG.

[Fig. 30]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor LED element) by 4th Embodiment shown in FIG. 24 and FIG.

[Fig. 31]

It is sectional drawing for demonstrating the manufacturing process of the nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) by the modification of 1st Embodiment.

[Fig. 32]

It is sectional drawing which showed the conventional nitride-based semiconductor light emitting element (nitride-based semiconductor laser element).

[Fig. 33]

It is sectional drawing for demonstrating the manufacturing process of the conventional nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) shown in FIG. 32.

[Fig. 34]

It is sectional drawing for demonstrating the manufacturing process of the conventional nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) shown in FIG. 32.

[Fig. 35]

It is sectional drawing for demonstrating the manufacturing process of the conventional nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) shown in FIG. 32.

[Fig. 36]

It is sectional drawing for demonstrating the manufacturing process of the conventional nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) shown in FIG. 32.

[Fig. 37]

It is sectional drawing for demonstrating the manufacturing process of the conventional nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) shown in FIG. 32.

[Fig. 38]

It is sectional drawing for demonstrating the manufacturing process of the conventional nitride-based semiconductor light emitting device (nitride-based semiconductor laser element) shown in FIG. 32.

[Explanation of symbols]

6 MQW light emitting layer (active layer) 7, 37, 47 p-type AlGaN clad layer (nitride-based semiconductor layer) 8, 38, 48 p-type GaN contact layer (nitride-based semiconductor layer) 9, 39, 49 Pd electrode layer (first electrode layer) 29 Pt / Pd electrode layer (first electrode layer) 21 p-type InGaN contact layer (nitride-based semiconductor layer) 32, 42 p type activation region (first conductive type region) 10 Metal film 41 p-type pad electrode 15 Silicon oxide film (insulating film)