Micromechanical component having a cap with a closure

Background technology The present invention relates to a micromachining type component comprising a substrate, a cavity, and a cap that defines the cavity, that is, partitions the contour of the cavity. The cap has an entry opening to reach the cavity.

Micromachining type components are capped for special purposes or for protection of their own. In particular, glass frit bonding or anode bonding for attaching a cap to the component is known. European Patent No. 1274648 describes packaging with a thin layer, the so-called OMM cap attachment (OMM = surface micromachining technology). The basis of this technique is the formation of a perforated layer of epitaxial polysilicon over a cavity containing a micromachining-type functional element. Perforation allows access to cavities from the outside during the fabrication of micromachining-type components.

Conventional semiconductor techniques have been described for cap closures, or more precisely perforation closures (eg, oxide precipitation or nitride precipitation). However, this semiconductor technology imposes strict boundary conditions on unique functional elements. In this case, the vacuum method, and thus the correspondingly low internal pressure of the component, is known. In this case, the composition of the internal atmosphere is, of course, less important.

Advantages of the invention Disclosure of invention The present invention starts with a micromachining-type component that includes a substrate, a cavity, and a cap that defines the cavity. The cap has an entry opening to reach the cavity. A core feature of the present invention is that the cap has a diaphragm for closing the entry opening.

It is advantageous that the cap is a thin layer cap. It is particularly advantageous that the diaphragm can be formed in the form of a single layer structure.

In an advantageous embodiment of the arrangement element, diaphragm key is located below the cap. This allows for a relatively simple construction of the cap with a diaphragm, allows easy access to the cavity through the externally exposed entry opening, and allows for encapsulation of high pressure within the cavity. To do.

In yet another advantageous configuration of the component, the diaphragm is placed on top of the cap. This makes it possible to enclose a particularly small internal pressure in the cavity.

In a third advantageous configuration of the component, the diaphragm is located in at least one layer inside the cap. Such an arrangement type is advantageous because both a high internal pressure and a low internal pressure in the cavity can be enclosed. Furthermore, it is advantageous that the cap does not have a diaphragm inside. Thus, it is possible to form a simple, particularly smooth, cavity top surface that does not interfere with the movable micromachining structure inside the cavity, and in some cases present. The inner surface of the cap is advantageous in this case as it can also act as a stopper for displacement of the micromachining structure in the direction of the cap.

It is also advantageous for the cap to have at least one perforation hole, a perforated hole, as an entry opening to reach the cavity. In an advantageous configuration of the constituent element, the entry opening is externally closed by a filling material. That is, in addition to the mechanical closure by the diaphragm, a permanent, especially airtight closure is provided.

The present invention also relates to a fabrication method for a micromachining type component with a substrate, a cavity, and a cap defining the cavity. The cap has an entry opening to reach the cavity. The essence of the method according to the invention is to create a diaphragm for closing the entry opening from a properly structured layer. By adhering and structuring the diaphragm layer, the sacrificial layer, the etch stop layer, and the cap layer, the cap can be provided on the micromachining type constituent element. This cap provides an access path that can be mechanically closed after the etching process using a diaphragm placed under the unique cap.

In an advantageous embodiment of the fabrication method according to the invention, the fabrication of an additional etch stop layer and an additional sacrificial layer prior to the layers listed above provides a cap with an inner diaphragm. Such a diaphragm is advantageous because it can be operated in two displacement directions.

The present invention is further a micromachining-type component comprising a substrate, a cavity, and a cap defining the cavity, wherein the cap has an entry opening to reach the cavity, and the cap The present invention relates to a method for closing a micromachining type component having a diaphragm for closing the entry opening. The method has the following major steps: That is, first the internal atmosphere in the cavity with the specified composition and specified pressure is adjusted, then the entry opening for reaching the cavity is mechanically closed by applying a diaphragm, followed by material application. Close the entry opening. In such a method, the regulation of the internal atmosphere and the closure of the cavity are separated from each other and thus sufficiently independent of each other.

In an advantageous embodiment of the closure method, a diaphragm is applied to a portion of the entry opening by a pressure difference induced between the cavity and the surrounding environment of the component. This is advantageous because the mechanical closure of the approach path can be done particularly easily and without direct manipulation of the components.

In yet another advantageous embodiment of the closing method, a diaphragm is applied to a portion of the entry opening by an induced electrostatic force action. This is advantageous because the mechanical closure of the approach path can be at least partially independent of the pressure characteristics in the cavity and in the surrounding environment of the component.

In the present invention, it is desirable to close the perforations in the cap EPI under the use of classical semiconductor technology (eg CVD, vacuum) so that the intended internal atmosphere at the defined internal pressure is adjusted. The present invention is recognized as a stratum having a method of belonging. In particular, the idea I want to explain creates a synergistic effect of having a conductor path in the cavity, which can act both as an electrical line and as a diaphragm for closing the entry opening.

A particularly advantageous embodiment is a flexible diaphragm underneath the perforated hole. This diaphragm allows ventilation of the cavity, in which case a gaseous coating (eg, an anti-adhesion coating) and filling gas can enter. Due to the significant pressure drop in the outer area of the cavity, the diaphragm is pressed from below through the hole to obtain a seal and closure is achieved. This is directly followed by a classical semiconductor coating process (eg CVD or sputtering) for closing the holes in the same equipment.

This allows for proper process implementation and hole geometry with semiconductor technology closure without additional hassle. This closure allows for control of the internal atmosphere with respect to pressure and composition and continues to allow unlimited treatment (apart from boundary conditions in component stress and resistance of anti-adhesion coatings).

Yet another embodiment of the present invention is described in claim 2 et seq.

Drawing FIG. 1 is a cross-sectional view showing the layered structure of the cap in the previous stage of the micromachining type constituent element according to the present invention having a cap with a closure. FIG. 2 is a cross-sectional view showing a micromachining type component according to the present invention having a cap with a closed portion in an open state. FIG. 3 is a cross-sectional view showing the layered structure of a cap in another pre-stage of a micromachining type component according to the invention with a cap with a closure. FIG. 4 is a cross-sectional view showing another micromachining type component according to the present invention having a cap with a closure in an open state. 5 and 6 are diagrams exemplifying one geometric example of a flexible diaphragm in the closure. FIG. 7 is a flow chart showing the steps of the method according to the invention for making micromachining type components with caps with closures. 8, 9 and 10 show various steps according to the invention for using a micromachining component with a closed cap to close the micromachining cap shown in FIG. It is sectional drawing which shows.

FIG. 11 is a flow chart showing method steps for closing a micromachining cap.

Description of Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the layered structure of the cap in the previous stage of the micromachining type constituent element according to the present invention, which has a cap with a closure. A layer that will later form a sacrificial layer, the polysilicon sacrificial layer 110 in this example, is deposited on the micromachining-type structure (not shown in detail). After deposition of this polysilicon sacrificial layer 110 and chemical mechanical polishing (CMP), the lower nitride layer 2, the polysilicon layer 4 and the upper nitride layer 3 are sequentially deposited and structured (pattern). Is made). A cap epitaxy layer 150 is adhered on the cap epitaxy layer 150. In this case, the polysilicon layer 4 has a partial range 4a and a partial range 4b. The lower nitride layer 2 has an access path to reach the polysilicon sacrificial layer 110 from the partial range 4b. The upper nitride layer 3 has an approach path for reaching the partial range 4b from the cap epitaxy layer 150. In this case, the sub-range 4a is geometrically (geometrically) separated from the sub-range 4b and forms an electrical conductor path. The partial area 4a is covered with nitride as a protective part during the subsequent sacrificial layer etching.

FIG. 2 shows a micromachining-type component of the present invention with a cap with a closure in an open state. In this case, a perforation portion, that is, a perforation portion 160 is formed in the cap epitaxy layer 150 by etching silicon. Subsequently, the partial range 4b of the polysilicon layer 4 is also removed by etching as a sacrificial layer. The polysilicon sacrificial layer 110 is also at least partially removed by etching. Therefore, after opening the perforated portion 160 at the time of sacrificial layer etching, approach paths 160 and 161 for reaching the cavity 10 from the upper side of the formed cap are formed. This approach can continue to be utilized to provide anti-adhesion coatings on micromachining structures and to provide an internal atmosphere of specified composition and specified pressure. The lower nitride layer 2 forms the diaphragm 2. This diaphragm 2 is suitable for closing the approach paths 160 and 161 due to displacement in the direction of the upper nitride layer 3. The diaphragm 2 has an attachment range 2a that is at least partially fixed to the upper nitride layer 3 and a closure range 2b that is located facing at least one perforation opening 160.

FIG. 3 shows the layered structure of the cap in another pre-stage of the micromachining type building block according to the invention with a cap with a closure. In this configuration of the present invention, the polysilicon sacrificial layer 110 is first coated with an inner nitride layer 30, and the polysilicon layer 30 is coated with an inner polysilicon layer 40, respectively. On top of that, the lower nitride layer 2 and another layer are adhered and structured as described above.

FIG. 4 shows another micromachining-type component according to the invention with a cap with a closure in an open state. After the etching process shown in FIG. 2 is used for the supplemented layer structure shown in FIG. 3, the inner nitride layer 30 is also exposed under the diaphragm 2. The inner nitride layer 30 has an approach road 162, and the approach road 162 is connected to the approach roads 160 and 161. By applying the diaphragm 2 to the inner nitride layer 30, the approach road 162 can be mechanically closed. As already described with reference to FIG. 2, the diaphragm 2 is also suitable for closing the approach paths 160,161 by the displacement of the closing range 2b of the diaphragm 2 in the direction of the upper nitride layer 3.

5 and 6 illustrate the geometric variations of the flexible diaphragm of the closure. The drawing illustrates a diaphragm 2 with a mounting range 2a, a closing range 2b, and a joint 2c. The black circle markings indicate the location of the perforated hole (also referred to above as the approach path to reach the cavity) 160 for diaphragm 2. Reference numeral 161 indicates an approach path through layer 2. The closed range 2b forms the sealing surface of the diaphragm 2, and the mounting range 2a forms the frame edge of the diaphragm 2. The joint 2c between the attachment range 2 and the closure range 2b may be formed in various shapes, numbers and dimensions, but it is advantageous to have flexible properties. 5 and 6 illustrate examples that are possible for this. However, the present invention is not limited to the illustrated examples.

FIG. 7 schematically shows the steps of the method according to the invention for making micromachining type components with caps with closures. A method for making a micromachining type component having a substrate, a cavity 10, and a cap defining the cavity 10 is described. In this case, the cap has an entry opening 160,161,162 to reach the cavity 10. In addition, the cap has a diaphragm 2b to close these access paths 160,161,162. The fabrication method is characterized by the following steps: (a) Prepare a micromachining type component with a first sacrificial layer 110 as the top layer. (b) The diaphragm layer 2 is adhered and structured, (c) The second sacrificial layer 4 is adhered and structured, (d) The etch stop layer 3 is adhered and structured, (e) Apply the cap layer 150 (f) An entry opening 160,161 is provided, at least a part of the second sacrificial layer 4b is removed, the diaphragm 2b is exposed, and at least a part of the first sacrificial layer 110 is removed by etching.

In one embodiment of the method, the lower etch stop layer 30 is additionally adherent and structured after step (a) and before step (b), followed by the lower sacrificial layer. 40 is adhered and structured. Further, in step (f), entry openings 160,161,162 are provided, in which case at least a portion of the lower sacrificial layer 40 is also removed.

8, 9 and 10 show the steps according to the invention for using a micromachining component with a closed cap to close the micromachining cap shown in FIG. It is shown.

After one or more optional process steps, such as an anti-adhesion coating on the inner surface of the cavity 10, the internal atmosphere is adjusted through the perforation opening 160 in the cavity 10 in step (A). This adjustment can specifically include the composition and pressure of the internal atmosphere.

Subsequently, in the second step (B), rapid pumping of the equipment, and thus rapid depressurization of the micromachining-type components and their cavities 10 in the external environment, is performed. The pressure difference between the internal atmosphere and the external atmosphere creates a force acting on the diaphragm 2, so that the closed area 2b is crimped to the upper surface of the cavity. As a result, the perforation opening 160 is mechanically closed from the inside.

In the third step (C), the perforation opening 160 is closed from the outside by applying a material. This can be done by conventional semiconductor technology, such as CVD or sputtering.

A variant of the shape of the mounted flexible diaphragm on the top surface of the cap or by another layer 30 with a sealing surface under diaphragm 2 and a through opening 162 as described with reference to FIGS. 3 and 4 above. In another configuration of the invention, the same mechanism can also be used to encapsulate the low internal pressure within the cavity 10. To do this, the internal atmosphere is adjusted accordingly in the first step (A) and the rapid pressure increase in the external surrounding environment of the micromachining type component and its cavity 10 in the second step (B). However, it is produced by ventilation of equipment using gas, for example. Subsequently, in the third step (C), the perforation opening 160 from the outside is closed by applying the material. When the diaphragm is arranged externally, the entire diaphragm can also be fixed and sealed by coating a material on the outer surface of the cavity.

FIG. 11 schematically shows the method steps for closing a micromachining type cap. This method has the following main method steps: (A) Adjust the internal atmosphere inside the cavity 10 and (B) The cavity 10 is mechanically closed by applying the diaphragm 2b to the approach path, and the cavity 10 is mechanically closed. (C) The perforation opening 160 is closed from the outside by applying the material.

In one embodiment of the invention, in step (B) the diaphragm 2b is applied to a portion of the entry openings 160,161,162 by the induced pressure difference between the cavity 10 and the surrounding environment of the constituent elements.

In another embodiment of the invention, in step (B) the diaphragm 2b is applied to a portion of the entry openings 160,161,162 by the induced electrostatic force action.

It is advantageous that the micromachining type constituent element described above is a constituent element mainly composed of silicon. The micromachining type constituent element may be, for example, an operating element (actuator) or a measuring element (sensor). It is particularly advantageous if the micromachining type component is formed as a yaw rate sensor or an acceleration sensor.

The process steps of the fabrication method described above have been simplified to make the drawings easier to read and do not include, for example, a protective structure for sacrificial layer etching. The diaphragm is formed, for example, as a nitride layer. Other suitable materials are also oxides and metals (eg tungsten). In the configuration of the present invention with an oxide sacrificial layer, a flexible diaphragm can also be made from polysilicon with a slight change in the process.

In addition to the above embodiment, another embodiment can be considered.

<figref num="1">It is sectional drawing which shows the layer structure of the cap in the pre-stage of the micromachining type constituent element by this invention which provided with the cap with the closure part.</figref><figref num="2">FIG. 5 is a cross-sectional view showing a micromachining type component according to the present invention having a cap with a closed portion in an open state.</figref><figref num="3">FIG. 5 is a cross-sectional view showing a layered structure of a cap in another pre-stage of a micromachining type component according to the invention with a cap with a closure.</figref><figref num="4">FIG. 6 is a cross-sectional view showing another micromachining type component according to the present invention having a cap with a closure in an open state.</figref><figref num="5">It is a figure which illustrates one example of the geometry of the flexible diaphragm of a closed part.</figref><figref num="6">FIG. 5 is an exemplary illustration of another geometrical embodiment of a flexible diaphragm in a closure.</figref><figref num="7">FIG. 5 is a flow chart showing steps of a method according to the invention for making micromachining type components with caps with closures.</figref><figref num="8">FIG. 5 is a cross-sectional view showing one step according to the invention for using a micromachining-type component with a cap with a closure to close the micromachining-type cap shown in FIG.</figref><figref num="9">FIG. 5 is a cross-sectional view showing another step according to the invention for using a micromachining component with a cap with a closure to close the micromachining cap shown in FIG.</figref><figref num="10">FIG. 5 is a cross-sectional view showing yet another step according to the invention for using a micromachining component with a cap with a closure to close the micromachining cap shown in FIG.</figref><figref num="11">It is a flowchart which shows the method step for closing a micromachining type cap.</figref>