Metallic thin-film laminated ceramic board

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a metal thin film laminated ceramic substrate, and more specifically, it is strong and has excellent film adhesion strength against thermal shock. Metal thin film laminated ceramic substrate.

【0002】

[Conventional technology]

Ceramics are members with excellent heat resistance, thermal shock resistance, and high fracture strength, and are used in a wide variety of aspects. It is also used as an IC package in the semiconductor industry. However, ceramics are rarely used alone in the semiconductor industry, etc., and are used after being subjected to some kind of processing. For example, when it is used as an IC package, a fine circuit wiring is formed of a metal thin film on a ceramic substrate, and a lead frame is joined. Therefore, ceramics are often chemically processed and used. Further, by firmly joining the ceramics and the metal, the functions of the ceramics can be fully exhibited.

【0003】

When joining ceramics and metal, it is difficult to join them directly. Therefore, a method of once metallizing the surface of ceramics by a certain method and then joining a target metal thin film body has been generally adopted. It was. In this method, the metallized paste is screen-printed on the surface of the ceramics, and then heated in a reducing atmosphere by the high melting point metal method. A metal having high chemical activity is physically vapor deposited on the surface of the ceramics by sputtering in a vacuum vessel or in a vacuum vessel. There is an active metal method in which the metal is heated in an inert gas atmosphere, or a chemical vapor deposition method in which the metal is heated in a vacuum and the vapor generated at that time is attached.

【0004】

FIG. 5 shows a schematic cross-sectional view of a metal thin film laminated ceramic substrate that has been conventionally used for IC packages and the like. In the figure, 12 indicates a ceramic substrate, a first metal thin film layer 23 made of Ti or the like formed on the surface of the ceramic substrate 12 by the above method, and Mo, Ni or the like on the first metal thin film layer 23. A second metal thin film layer 24 and a third metal thin film layer 25 made of Ag, Cu, etc. are formed on the second metal thin film layer 24 by a chemical vapor deposition method or a physical vapor deposition method, respectively, and Cu or the like is further formed as the outermost layer. A plating film layer 26 is formed by electrolytic plating, and a metal thin film laminate 27 is formed by the first metal thin film layer 23, the second metal thin film layer 24, the third metal thin film layer 25, and the plating film layer 26, and these metal thin films are formed. The metal thin film laminated ceramic substrate 21 is composed of the laminate 27 and the ceramic substrate 12.

【0005】

[Problems to be Solved by the Invention]

When the LSI element is mounted on a TAB (Tape Automated Bonding) in which a Cu wiring pattern with a thickness of 35 μm is formed, it is necessary that the Cu wiring does not break in the TAB in the LSI peeling test. For that purpose, in the peel test to measure the adhesion strength of the film, the value of the adhesion strength of the film is 2 kg / mm.² It is said that it is necessary to be above. It is said that the same film adhesion strength is required for metal thin film laminated ceramic substrates, but in reality, the film adhesion strength is even higher when reproducibility and reliability due to changes in conditions during thin film formation are taken into consideration. Is desired. It is also required that the adhesion strength of the thin film is not deteriorated by thermal shock.

【0006】

However, in the conventional metal thin film laminated ceramic substrate 21 having the above-described configuration, the film adhesion strength is not sufficient, and the value of the film adhesion strength in the peel test is 3 kg / mm.² There was a problem that there was almost no such thing that exceeded the above, and the deterioration due to thermal shock was large.

【0007】

That is, in the conventional metal thin film laminated ceramic substrate 21, the first metal thin film layer 23 passes through the second metal thin film layer 24 which should play a role as a barrier layer in the high temperature heat resistance test and the high temperature holding test, and the third metal thin film is formed. There is also a problem that the surface of the third metal thin film layer 25 is discolored to black due to diffusion to the surface of the layer 25, and as a result, the film adhesion strength of the plating film layer 26 formed by electrolytic plating is lowered.

【0008】

The present invention has been made in view of such a problem, and the diffusion of the metal of the first layer to the upper layer is prevented, and 3 kg / mm in the peel test.² It is an object of the present invention to provide a metal thin film laminated ceramic substrate having high film adhesion strength and excellent thermal shock resistance.

【0009】

[Means for solving problems]

In order to achieve the above object, the metal thin film laminated ceramic substrate according to the present invention is a metal thin film laminated ceramic substrate in which a plurality of layers of metal thin films are laminated on the ceramic substrate. First metal thin film layer composed of one or more elements selected from Group VIA excluding Mo, Periodic table excluding Cr and W on the first metal thin film layer One selected from Group VIA or Ni On the second metal thin film layer composed of the above elements, the third metal thin film layer composed of one or more elements selected from Group IB of the periodic table on the second metal thin film layer, and on the third metal thin film layer. It is characterized in that a fourth metal thin film layer composed of the same elements as the second metal thin film layer and a fifth metal thin film layer composed of the same elements as the third metal thin film layer are laminated on the fourth metal thin film layer. It is supposed to be.

【0010】

[Action]

According to the metal thin film laminated ceramic substrate according to the present invention, in a metal thin film laminated ceramic substrate in which a plurality of layers of metal thin films are laminated on the ceramic substrate, the periodic table IVA group or VIA group excluding Mo is obtained on the ceramic substrate. A first metal thin film layer composed of one or more elements selected from, and a first metal thin film layer composed of one or more elements selected from Group VIA of the periodic table excluding Cr and W or Ni on the first metal thin film layer. 2 metal thin film layer, 3rd metal thin film layer composed of one or more elements selected from the periodic table IB group on the 2nd metal thin film layer, the 2nd metal thin film layer on the 3rd metal thin film layer Since the fifth metal thin film layer made of the same element as the third metal thin film layer is laminated on the fourth metal thin film layer made of the same element as the above, the first metal thin film layer Diffuse is prevented, the ceramic substrate, the metal thin film laminate laminated on the ceramic substrate, and each metal thin film layer in the metal thin film laminate are firmly bonded, and 3 kg / mm in the peel test.² It has the above film adhesion strength, and its bond does not deteriorate even if it receives thermal shock.

【0011】

In the above configuration, the first metal thin film layer composed of one or more elements selected from Group IVA or Group VIA of the Periodic Table is formed on the surface of the ceramic substrate. Since it has high activity with respect to the ceramic substrate and easily diffuses into the ceramic substrate, it is firmly bonded to the ceramic substrate, and from the periodic table VIA group or Ni formed on the first metal thin film layer. It easily diffuses into the second metal thin film layer composed of one or more selected elements, and is firmly bonded to the second metal thin film layer.

【0012】

Examples of the ceramic substrate include oxide-based ceramic substrates such as alumina and non-oxide ceramic substrates such as aluminum nitride and silicon carbide, but the present invention particularly has a problem in film adhesion strength with the metal thin film layer. It is effective when an alumina substrate is used. Examples of the metal used for the first metal thin film layer include Ti, Zr, Cr and the like, and examples of the metal used for the second metal thin film layer include Mo, Ni and the like. In particular, the first metal thin film layer is Ti. When is used, it is easily bonded to alumina because it is easy to form an intermetallic compound, and it is also strongly bonded to Mo and the like because it is easy to form an alloy.

【0013】

Next, the laminated film formed on the second metal thin film layer will be described. The second metal thin film layer and the fourth metal thin film layer are made of the same metal, and the second metal thin film layer and the second metal thin film layer A so-called sandwich structure is adopted in which a third metal thin film layer composed of one or more elements selected from Group IB of the periodic table is interposed between the fourth metal thin film layer. By adopting the sandwich structure, the first metal thin film layer such as Ti dissolves mainly in Group IB elements while diffusing the third metal thin film layer, passes through these layers, and is said to be the first. 5 It does not diffuse to the metal thin film layer, and deterioration of the film adhesion strength of the outermost plating film layer due to the diffusion of the first metal thin film layer is prevented.

【0014】

Examples of the metal used for the third metal thin film layer include Cu, Au, Ag and the like. The fifth metal thin film layer is also made of the same metal as the third metal thin film layer.

【0015】

By forming a metal thin film laminate in which sandwich-like structures of different kinds of metals are overlapped and laminated in this way, the metal thin film layers diffuse each other, and the thin film layers of each other are firmly bonded to each other. It is also firmly bonded to the ceramic substrate to form a metal thin film laminated ceramic substrate having high film adhesion strength.

【0016】

[Examples and Comparative Examples]

Hereinafter, examples of the metal thin film laminated ceramic substrate according to the present invention will be described with reference to the drawings.

【0017】

[Example 1] FIG. 1 is a schematic cross-sectional view showing the structure of the metal thin film laminated ceramic substrate in Example 1. In the figure, 12 indicates a ceramic substrate, which is Al.₂ O₃ A first metal thin film layer 13 made of Ti on the surface of a ceramic substrate 12 made of, a second metal thin film layer 14 made of Mo on the first metal thin film layer 13, and Cu made of Cu on the second metal thin film layer 14. The third metal thin film layer 15, the fourth metal thin film layer 16 made of Mo on the third metal thin film layer 15, the fifth metal thin film layer 17 made of Cu on the fourth metal thin film layer 16, and the fifth metal thin film layer A plating film layer 18 made of Cu is further laminated on the 17 as the outermost layer, and these first metal thin film layer 13, second metal thin film layer 14, third metal thin film layer 15, fourth metal thin film layer 16, fifth. The metal thin film layer 17 and the plating film layer 18 form the metal thin film laminate 19, and the metal thin film laminate 19 and the ceramic substrate 12 constitute the metal thin film laminated ceramic substrate 11.

【0018】

Next, a method for manufacturing the metal thin film laminated ceramic substrate 11 will be described. First, Al₂ O₃ Al has high chemical activity on the surface of the ceramic substrate 12 made of the above material by a chemical vapor deposition method or a physical vapor deposition method.₂ O₃ The first metal thin film layer 13 is formed to a thickness of 0.05 to 0.20 μm using Ti that easily reacts with. At this time, Ti is the lower Al₂O₃ It reacts with the ceramic substrate 12 made of the material to form an intermetallic compound.

【0019】

A second metal thin film layer 14 made of Mo, a third metal thin film layer 15 made of Cu, and a fourth metal thin film layer 16 made of Mo are formed on the first metal thin film layer 13 by a chemical vapor deposition method or a physical vapor deposition method. The thickness of the second metal thin film layer 14 was set to 0.10 to 0.20 μm, the thickness of the third metal thin film layer 15 was set to 0.01 to 0.02 μm, and the thickness of the fourth metal thin film layer 16 was set to 0.10 to 0.30 μm. The second metal thin film layer 14, the third metal thin film layer 15, and the fourth metal thin film layer 16 serve as a barrier for preventing the first metal thin film layer 13 from bleeding into the fifth metal thin film layer 17. The third metal thin film layer 15 is preferably a thin layer of 0.01 to 0.02 μm, and when a thicker layer is used, the film adhesion strength tends to decrease.

【0020】

A fifth metal thin film layer 17 is formed on the fourth metal thin film layer 16 by a chemical vapor deposition method or a physical vapor deposition method to a thickness of 0.20 to 0.50 μm using Cu having good conduction resistance. After that, the plating film layer 18 for increasing the conduction effect and being used for multiple purposes is formed to a thickness of 3 to 4 μm by a chemical plating method. The plating film layer 18 is formed by using Group IB elements of the same family as the fifth metal thin film layer 17.

【0021】

The film thickness from the first metal thin film layer 13 to the plating film layer 18 was shown to be a desirable value when a fine circuit wiring was formed and used for an IC package, but it can be set to an arbitrary value depending on the purpose. It can be changed and dealt with.

【0022】

A general known method can be used as the physical vapor deposition method, and examples thereof include a vacuum vapor deposition method, an ion beam vapor deposition method, a sputtering method, and the like, which have a feature that the material and film thickness can be freely selected. ing. Further, a generally known method can be used for the chemical plating method for forming the uppermost layer, and examples thereof include an electrolytic plating method and an electroless plating method.

【0023】

Tables 1, 2 and 3 below show the metal thin film laminated ceramic substrates according to the above Example 1 and another example prepared by changing the type of metal constituting the metal thin film laminate 18 in the above Example 1. The measurement result of the film adhesion strength in the metal thin film laminated ceramic substrate which concerns on the comparative example composed of the conventional metal thin film layer is shown. The measurement results of the film adhesion strength are the normal case where the peel test is performed, and after 200 cycles of + 150 ° C / -60 ° C thermal cycle for 30 minutes each and the temperature rise / fall rate of 10 ° C / min, Ni The case where the lead wire 22 is joined and the peel test is performed (indicated after the thermal cycle in the table) is shown.

【0024】

[table 1]

<img file="JP2762007B2_D0001.tif" />【0025】

[Table 2]

<img file="JP2762007B2_D0002.tif" />【0026】

[Table 3]

<img file="JP2762007B2_D0003.tif" />【0027】

In the examples and comparative examples shown in Tables 1, 2 and 3, a solder pull test as shown in FIG. 2 was carried out as a method for measuring the film adhesion strength by the peel test. First, a Ni lead wire 22 having a diameter of about 1 mm is soldered onto the metal thin film laminated ceramic substrate 11, and then each pin is pulled vertically at a speed of 10 mm per minute to break it, and the strength at the time of breaking is determined. The film adhesion strength was used. At this time, solder breakage and interface breakage between the solder and the metal thin film could not be evaluated as proper film strength, so they were deleted from the data.

【0028】

As is clear from Tables 1, 2 and 3, the normal film adhesion strength of Comparative Examples 1 to 18 is 3 kg / mm.² Some of them showed the above values, but when the film adhesion strength was measured after the thermal shock reliability test, the strength deteriorated, and the others showed 3 kg / mm.² None of them showed the above values, and the film adhesion strength was deteriorated by thermal shock.

【0029】

On the other hand, those of Examples 1 to 18 showed stable strength even after the thermal shock reliability test, and the film adhesion strength was the target 3 kg / mm.² The above values could be obtained.

【0030】

Next, using the metal thin film laminated ceramic substrates obtained in Example 1 and Comparative Example 1, heat treatment was performed at 850 ° C for 10 minutes, and then surface analysis was performed using EPMA. The results are shown in FIGS. 3 and 4. In FIGS. 3 and 4, the vertical axis represents the diffraction intensity and the horizontal axis represents the diffraction angle. As is clear from this result, titanium was not observed on the surface of the metal thin film laminated ceramic substrate used in Example 1, whereas titanium was detected on the surface of the metal thin film laminated ceramic substrate obtained in Comparative Example 1. It can be seen that the titanium atoms are thermally diffused to the surface.

【0031】

Further, when the metal thin film laminated ceramic substrates of Example 1 and Comparative Example 14 were heat-treated at 600 ° C. for 2 hours before being electroplated, the metal thin film laminated ceramic substrates of Example 1 were not discolored at all. On the other hand, the one of Comparative Example 14 turned brown. From this result, it can be seen that in the conventional one, Ti is easily diffused to the surface layer by heat treatment, whereas in the example, the thermal diffusion of Ti is prevented.

【0032】

This is presumed to be due to the following reasons. Since Ti in the first layer is very reactive and active, the Ti is first diffused into Mo in the second layer by heat treatment. Ti is further diffused into Cu in the third layer and dissolved in Cu. Since Ti and Cu are easily dissolved in each other, even a thin film having a Cu film thickness of about 0.01 μm is easily dissolved in solid solution. Ti that could not be completely dissolved in Cu is further diffused into Mo in the 4th layer, but the amount is so small that it does not pass through the 4th layer. Therefore, in the metal thin film laminated ceramic substrate of Example 1, heat diffusion to the surface of Ti is prevented even if heat treatment is performed. This speculation is also confirmed by SIMS analysis in the depth direction.

【0033】

As described above, in the metal thin film laminated ceramic substrate according to the embodiment, the first metal thin film layer 13 does not diffuse to the surface layer even in a high temperature state, so that the film adhesion strength does not deteriorate even after the thermal impact test. Conceivable.

【0034】

[Effect of the invention]

As described in detail above, the metal thin film laminated ceramic substrate according to the present invention is a metal thin film laminated ceramic substrate in which a plurality of layers of metal thin films are laminated on the ceramic substrate. A first metal thin film layer composed of one or more elements selected from Group VIA excluding Group or Mo, and a periodic table excluding Cr and W selected from Group VIA or Ni on the first metal thin film layer. A second metal thin film layer composed of one or more elements, a third metal thin film layer composed of one or more elements selected from Group IB of the periodic table on the second metal thin film layer, and the third metal thin film layer. Since the fourth metal thin film layer made of the same element as the second metal thin film layer is laminated on the top, and the fifth metal thin film layer made of the same element as the third metal thin film layer is laminated on the fourth metal thin film layer. , The diffusion of the first metal thin film layer can be prevented, and the ceramic substrate and the metal thin film laminate and each metal thin film layer in the metal thin film laminate can be firmly bonded, and as a result, in the peel test. 3kg / mm² It is possible to provide a metal thin film laminated ceramic substrate having the above film adhesion strength and whose film adhesion strength does not change even when subjected to thermal shock.

[Simple explanation of drawings]

[Figure 1]

It is a schematic cross-sectional view which showed the metal thin film laminated ceramics substrate which concerns on Example of this invention.

[Figure 2]

It is a perspective view which showed the film adhesion strength measurement method by a peel test.

[Fig. 3]

It is a graph which shows the result of elemental analysis of the surface using EPMA after heat-treating the metal thin film laminated ceramic substrate obtained in Example 1.

[Fig. 4]

It is a graph which shows the result of elemental analysis of the surface using EPMA after heat-treating the metal thin film laminated ceramic substrate obtained in Comparative Example 1.

[Fig. 5]

It is a schematic cross-sectional view which showed the conventional metal thin film laminated ceramics substrate.

[Explanation of symbols]

11 Metal Thin Film Laminated Ceramic Substrate 12 Ceramic substrate 13 First metal thin film layer 14 Second metal thin film layer 15 Third metal thin film layer 16 4th metal thin film layer 17th metal thin film layer