JP4857718B2 - Micromachine mixed electronic circuit device and method for manufacturing micromachine mixed electronic circuit device - Google Patents

Description

  The present invention relates to a micromachine mixed electronic circuit device in which, for example, a microelectromechanical element of a micron order or a nano order size and a so-called micromachine element and an electronic circuit are formed on a common substrate, and a method for manufacturing a micromachine mixed electronic circuit device. .

Research and development of micro electro mechanical system (MEMS) elements are remarkable, and in recent years, their use in various fields such as sensors, actuators, optics, biotechnology, and high-frequency circuits has been expanded.
Some devices, such as acceleration sensors and micromirror devices, for example, have already been commercialized and can be found in everyday life.
Along with such progress, a single-function MEMS, for example, can be incorporated into an electronic circuit that constitutes its peripheral circuit and built with a mixed machine of a micromachine and an electronic circuit to give a function as a system. It is considered that convenience can be further improved by configuring the electronic device.

  In the manufacture of micromachines, many semiconductor manufacturing technologies are usually applied, the footprint is reduced by downsizing the micromachine, and SiP (System in Package), which is performed by compounding semiconductor devices ) And SoC (System on Chip) are available, so that a micromachine and a semiconductor circuit constituting its peripheral circuit are combined, in other words, an electronic circuit device mixed with a micromachine on a common substrate. There is a growing demand for realization of configuration.

As described above, when a micromachine element is incorporated in an electronic circuit, the micromachine structure in which mechanical operations such as vibration, movement, and rotation of the micromachine are performed does not hinder the required operation. A cavity is formed around the arrangement portion.
Usually, the formation of the cavity is performed by forming a sacrificial layer in advance in the manufacturing process of the cavity, forming a micromachine structure on which the mechanical operation described above is performed, and then sacrificing it. By etching away the layer, the micromachine structure is operatively formed in the cavity (see, for example, Patent Document 1).

By the way, when configuring an electronic circuit device mixed with a micromachine, the wiring portion in the electronic circuit portion is composed of Al wiring excellent in conductivity.
On the other hand, in the manufacture of a micromachine, the semiconductor manufacturing technique described above can be applied, and since it has excellent mechanical characteristics, it is desired to be formed of polysilicon. In the case of this polysilicon, electrical characteristics such as phosphorous-doped polysilicon are required to be heat-treated at a relatively high temperature in order to reduce the resistance. On the other hand, the wiring of the electronic circuit is composed of a metal layer having low heat resistance such as Al. For this reason, this wiring portion is formed after the micromachine is formed.

  However, according to this procedure, since an interlayer insulating layer is also deposited on the micromachine, the formation of a cavity that enables the mechanical operation of the micromachine eliminates the wiring interlayer insulating layer in this portion. Subsequently, it is necessary to eliminate the sacrificial layer under the micromachine structure.

Many methods for forming an opening in an insulating layer are already known. For example, a method for manufacturing a semiconductor device in which an opening is formed in a portion such as a photodiode that needs to receive light has been proposed (see, for example, Patent Document 2).
However, it is difficult to say that this technique is immediately applied to the above-described micromachine mixed electronic circuit.
That is, in the invention described in Patent Document 2, a silicon oxide film formed so as to cover a base member (for example, a light receiving surface of a light receiving element) is decisively formed in a defined region on the light receiving surface. It is a technique. In this case, the opening is formed by wet etching so that the surface film such as the antireflection film on the surface of the light receiving surface is not damaged. In this wet etching, the opening is widened due to its isotropic property. Therefore, in the present invention, an etching stopper is formed on the light receiving surface so that the opening is avoided and etching is performed in a predetermined region of the light receiving surface. This is due to the technique.

On the other hand, in the micromachine, the entire periphery other than the support portion, that is, the upper and surrounding interlayer insulating layers and the lower sacrificial layer is excluded so that the micromachine operation structure portion can perform mechanical operation. Therefore, it is necessary to form a cavity.
The formation of such a cavity needs to take into consideration the influence on the adjacent electronic circuit, particularly the influence on the interlayer insulating layer of the wiring part, and the accompanying decrease in the reliability and durability of the wiring pattern.
JP-A-9-162462 JP 2002-246363 A

  The present invention relates to an electronic circuit device mixed with a micromachine, in which it is easy to form a cavity that can reliably perform mechanical operation, and to improve the influence of deterioration of characteristics, durability, etc. on adjacent electronic circuits. The present invention provides a micromachine mixed electronic circuit device and a method of manufacturing a micromachine mixed electronic circuit device which can be realized.

A micromachine mixed electronic circuit device according to the present invention is a micromachine mixed electronic circuit device in which a micromachine element and an electronic circuit are mixedly mounted on a common substrate, and is formed in an electronic circuit forming portion on the substrate. Corresponding to the electronic circuit element, the wiring part formed on the electronic circuit forming part and having a multilayer wiring pattern laminated via the wiring interlayer insulating layer, and the micromachine element forming part of the substrate, A cavity formed in a wiring interlayer insulating layer continuous with the wiring interlayer insulating film, an etching protection wall disposed on an inner wall surface of the cavity of the wiring interlayer insulating layer, and formed on the substrate in the cavity A micromachine element comprising a conductive pattern and a micromachine operation structure portion located below the uppermost wiring pattern of the wiring portion, and the micromachine An etching stop layer disposed under the conductive pattern of the child, and the micromachine element has an entire outer surface other than the mechanical support portion of the micromachine operation structure portion in a non-contact state with the other portion in the cavity portion. It is exposed and held.

Method of manufacturing an electronic circuit device micromachine mixed according to the invention, on a common substrate, a manufacturing method of an electronic circuit device micromachine mixed to the micromachined device and the electronic circuit is formed by mixed, the electronic circuitry on the substrate the formations, a first step of forming an electronic circuit elements, the formation of micromachined devices on the substrate, forming an etch stop layer, a second for forming the conductive pattern of the micromachined device on the etching stop layer A step, a third step of forming a sacrificial layer on the micromachine element forming portion on the conductive pattern, and a fourth step of forming a micromachine operation structure portion on which the mechanical operation of the micromachine element is performed on the sacrificial layer . a step, a fifth step of performing heat treatment for activation of the conductive pattern and the micromachine operation structure, the upper A wiring portion in which a multilayer wiring pattern is laminated via a wiring interlayer insulating layer is formed on the formation portion of the electronic circuit, and the wiring structure is embedded so that the micromachine operation structure portion is embedded on the formation portion of the micromachine element. A sixth step of forming only an interlayer insulating layer, and a trench is dug in the wiring interlayer insulating layer at a predetermined distance from the micromachine operating structure section at least between the micromachine operating structure and at least the electronic circuit section. a seventh step of writing, a eighth step of forming an etching protection wall filled with an etching resistant material in the groove, in the wiring interlayer insulating layer, thereby forming an opening to expose the micromachine operation structure, the the sacrificial layer underneath the micromachined operation structure and a ninth step of etching away, to the arrangement of the micromachine operation structure,該Ma All outer surfaces other than the mechanical support Kuromashin operation structure, characterized in that as the cavity for holding the other portion and a non-contact state is formed.

  The present invention takes the same process as the above-described method for manufacturing an electronic circuit device mixed with a micromachine, but after the above-mentioned isotropic etching process, a process of removing the etching protection wall is taken.

  According to the above-described electronic circuit device in which microelectromechanical elements having micro-order and nano-order sizes according to the present invention are mixed, a protective wall is interposed between the micromachine operating structure section and the electronic circuit section adjacent thereto. Therefore, it is possible to avoid the deterioration of the insulation due to the damage of the wiring interlayer insulating layer of the electronic circuit portion, particularly the wiring pattern, and the deterioration of the electrical and mechanical characteristics of the wiring pattern due to the time.

Further, according to the manufacturing method of the present invention, the formation of the cavity for mobilization of the micromachine operation structure portion with respect to the wiring interlayer insulating layer is performed by providing an etching protection wall at a position separated from the micromachine operation structure portion. Without affecting the wiring part of the electronic circuit, it is possible to perform reliably including the etching for removing the sacrificial layer under the micromachine operation structure part.
Therefore, it is possible to form a cavity where the operation of the micromachine can be performed reliably without impairing the reliability of the electronic circuit.

Embodiments of a micromachine mixed electronic circuit device and a method of manufacturing a micromachine and electronic circuit mixed device according to the present invention will be described with reference to the drawings. However, the present invention is not limited to this example. Needless to say.
1 to 4 are schematic cross-sectional views of manufacturing steps of an example of a method for manufacturing a micromachine mixed electronic circuit device.
In this example, a micromachine mixed electronic circuit device constituting a high frequency filter in which a micromachine element (that is, a microelectromechanical element) constituting a high frequency resonator and an electronic circuit of its peripheral circuit are formed on a common substrate is illustrated. Is.
In this case, as shown in FIG. 1A, a circuit element 2 constituting an electronic circuit is formed on a substrate 1 made of, for example, a silicon semiconductor. The circuit element 2 is formed by a well-known method similar to a normal method for manufacturing a semiconductor integrated circuit. In the figure, only one MOS constituting the CMOS is disclosed as a circuit element.
In a field part other than the circuit element formation part of the silicon substrate 1, an element isolation insulating layer 3 is formed by, for example, local thermal oxidation (LOCOS).

On the silicon substrate 1, a lower insulating layer 9d made of SiO ₂ is deposited by, for example, CVD (Chemical Vapor Deposition).
Then, the etching stop layer 4 and the conductive pattern 5 of the resonator are formed on the formation portion of the micromachine element, that is, the resonator on the lower insulating layer 9d.
The etching stop layer 4 is formed by, for example, forming a SiN layer on the entire surface by low pressure CVD and etching away unnecessary portions by photolithography.
As the conductive pattern 5, for example, phosphorous (P) -doped polysilicon is similarly formed on the entire surface, and is formed into a required pattern by photolithography. The conductive pattern 5 is formed with terminal patterns 51 and 52 for supplying electric charges to the micromachine operation structure where mechanical vibration of the MEMS resonator is performed, and an input signal line 5i and an output signal line 5o.

As shown in FIG. 1B, a sacrificial layer 6 is formed on the formation portion of the MEMS element on the conductive pattern 5. The sacrificial layer 6 is formed by, for example, forming a silicon oxide, for example, SiO ₂ layer on the entire surface by CVD, patterning the same by photolithography, and supporting the finally formed micromachine operating structure 7 on the terminal patterns 51 and 52. It is assumed that the opening 6a is formed in the portion, that is, the portion constituting the pier.

Next, as shown in FIG. 2A, a polysilicon layer is formed on the sacrificial layer 6 including the inside of the opening 6a by, for example, CVD, and is patterned by photolithography, for example, a micromachine operation in which the planar shape is a rectangular shape. The structure part 7 is formed.
Thereafter, the activation process of the conductive pattern 5 and the micromachine operation structure unit 7 is performed under normal impurity activation conditions. This treatment is performed, for example, by heat treatment at 800 ° C. to 900 ° C. in a nitrogen atmosphere.
Then, as shown in FIG. 2B, the wiring portion 8 is formed. In this wiring portion 8, as usual, for example, a multilayer wiring pattern 10 is laminated by interposing a multilayer wiring interlayer insulating layer 9. The predetermined wiring patterns 10 stacked are connected via a connecting conductor 10c formed in a so-called via hole formed through the wiring interlayer insulating layer 9. In this case, as in a normal semiconductor integrated circuit device, the wiring interlayer insulating layer 9 is deposited over the entire surface including the formation part of the electronic circuit and the formation part of the micromachine. The wiring interlayer insulating layer 9 is composed of SiO _{2 which} has a common etching solution with the sacrificial layer 6.

  Next, as shown in FIG. 3A, for example, the micromachine operation structure unit 7 is surrounded by the micromachine operation structure unit 7 so as to be interposed at least between the formation part of the micromachine operation structure unit 7 and the wiring unit 8. The groove 11 is formed in a position across the wiring interlayer insulating layer 9 at a position separated from the periphery by a required gap, for example, by anisotropic etching by dry etching.

  As shown in FIG. 3B, a protective material layer 12M that has resistance to etching and can be embedded in the groove 11 at a low temperature, for example, a SiN etching protective material, for example, is formed by plasma CVD to fill the groove 11. . In this way, the etching protection wall 12 is formed in the groove 11.

As shown in FIG. 4A, an etching opening 12a is formed on the arrangement portion of the micromachine operation structure portion 7 of the etching protection material layer 12M by application of a photolithography technique.
Next, as shown in FIG. 4B, through the opening 12a, the wiring interlayer insulating layer 9 and the sacrificial layer 6 are etched away by wet etching with hydrofluoric acid, that is, isotropic etching, and the cavity 13 is formed.
Further, a contact window 18 is opened by pattern etching by photolithography in the wiring interlayer insulating layer 9 on the wiring pattern 10 connected to the outside of the wiring portion 8.

  In this way, in the cavity 13, the micromachine operation structure portion 7 is removed by the elimination of the sacrificial layer 6, and all but the support portion 14 by the bridge piers connected to the terminal patterns 51 and 52 through the openings 6 a of the sacrificial layer 6 are present. The entire periphery, that is, the entire outer surface is separated from the other portion, and the micromachine element 15 having the micromachine operation structure portion 7 having a hollow structure in which the mechanical operation, in this example, vibration is not hindered is configured. . Then, a target micromachine mixed electronic circuit device 17 in which an electronic circuit 16 having the circuit element 2 and the wiring portion 8 is formed on the common substrate 1 on which the micromachine element 15 is formed is configured.

  The electronic circuit device 17 mixed with a micromachine having this configuration is applied to the micromachine operation structure section 7 by applying a required voltage to the micromachine operation structure section 7 by means of the terminal leads 51 and 52, while the electrostatic charge is accumulated in the micromachine operation structure section 7. When an input signal is introduced into the signal line 5i, the micromachine operation structure unit 7 resonates with an input signal having a frequency that matches the natural frequency of the micromachine operation structure unit 7, and vibrates with a large amplitude. As a result, a filter circuit having a predetermined frequency can be configured by the micromachine element 15 and the electronic circuit unit 16 constituting the peripheral circuit.

  The electronic circuit device 17 mixed with a micromachine having this configuration is based on a configuration in which an etching protection wall 12 is interposed between the micromachine operating structure portion 7 and the electronic circuit portion 16 adjacent thereto. In particular, it is possible to avoid deterioration in insulation due to the wiring interlayer insulating layer 10 of the wiring pattern being damaged by the etching that forms the cavity portion 13 and deterioration of the electrical and mechanical characteristics of the wiring pattern over time due to this.

Further, according to the manufacturing method of the present invention, the cavity 13 for movability of the micromachine operation structure portion 7 with respect to the wiring interlayer insulating layer 10 is formed by providing an etching protection wall at a position separated from the micromachine operation structure portion 7. Therefore, the influence on the wiring portion of the electronic circuit portion 16 can be avoided, and the removal including the etching of the sacrifice layer 6 under the micromachine operation structure portion 7 can be performed reliably.
Therefore, it is possible to form a cavity where the operation of the micromachine can be performed reliably without impairing the reliability of the electronic circuit.

In the manufacturing method described above, the cavity 13 is formed only by wet etching. However, etching can be performed to a required depth by dry etching prior to wet etching, and then performed by the above-described wet etching. .
The example shown in FIGS. 1 to 4 is a case where the etching protection wall is finally left, but an electronic circuit device having a structure in which the etching protection wall does not remain can be configured.

Each of A and B in FIGS. 5 to 7 is a cross-sectional view of the main part of each step of another example of the production method of the present invention.
Another example of the manufacturing method of the present invention will be described with reference to FIGS.

  Also in this example, as shown in FIG. 5A, the circuit element 2, the wiring interlayer insulating layer 9 and the wiring pattern 10 are formed on the substrate 1 made of a common silicon semiconductor by, for example, the same method as described in FIGS. Then, the wiring portion 8 and the micromachine operation structure portion 7 are formed.

In this example, a passivation film 19 made of SiN is formed on the deposited wiring interlayer insulating layer 9 entirely by, for example, plasma CVD.
Next, in this example, as shown in FIG. 5B, the contact window 18 and finally the micromachine are formed across the wiring interlayer insulating layer 9 on the wiring pattern 10 connected to the outside of the wiring portion 8 and the passivation film 19. A recess 20 is formed on the formation portion of the cavity 13 to be formed.

Next, as shown in FIG. 6A, as described in FIG. 3A, for example, the micromachine operation structure portion 7 is surrounded so as to be interposed at least between the formation portion of the micromachine operation structure portion 7 and the wiring portion 8. In addition, the groove 11 is formed at a position across the wiring interlayer insulating layer 9 at a position spaced from the periphery of the micromachine operation structure portion 7 by anisotropic etching, for example, by dry etching.
As shown in FIG. 6B, for example, a photoresist is spin-coated, and the groove 11 is filled with a photoresist that can be satisfactorily embedded in the groove 11 at a low temperature to form an etching protection wall 12 and a contact window. A protective film 23 covering 18 is formed. An opening 22 is formed on the recess 20 of the protective film 23.

As shown in FIG. 7A, isotropic etching is performed by wet etching by etching of BHF (buffered hydrofluoric acid) with which the protective wall 12 made of photoresist is resistant through the opening 22 to remove the wiring interlayer insulating layer 9 and the sacrificial layer 6 by etching. To form the cavity 13.
Thereafter, as shown in FIG. 7B, the etching protective wall 12 and the protective film 23 are removed by the solvent.

  In this way, in the cavity 13, the micromachine operation structure portion 7 is removed by the elimination of the sacrificial layer 6, and all but the support portion 14 by the bridge piers connected to the terminal patterns 51 and 52 through the openings 6 a of the sacrificial layer 6 are present. The entire periphery, that is, the entire outer surface is separated from the other portions, and the micromachine element 15 having the micromachine operation structure portion 7 in which the mechanical operation, in this example, vibration is not hindered is configured. Then, a target micromachine mixed electronic circuit device 17 in which an electronic circuit 16 having the circuit element 2 and the wiring portion 8 is formed on the common substrate 1 on which the micromachine element 15 is formed is configured.

Also in the case of this manufacturing method, as in the above-described example, the formation of the cavity 13 can be easily performed and the influence on other parts can be effectively avoided.
Therefore, according to the present invention, a highly reliable electric circuit device mixed with a micromachine can be configured.

In this example, as the electronic circuit device 17 mixed with a micromachine, the etching protection wall 12 is excluded. However, the material of the etching protection wall 12 may be selected so that the etching protection wall 12 remains. .
5-7, the same code | symbol is attached | subjected to the part corresponding to FIGS. 1-4, and duplication description is abbreviate | omitted.

In each of the above-described configurations and manufacturing methods, the wet etching that forms the cavity 13 does not erode, for example, polysilicon of the constituent material of the micromachine 15 or has extremely low erodibility, and the wiring interlayer insulating layer 9 and the sacrificial layer 6 are not etched. For example, a hydrofluoric acid-based etchant having a high etching property with respect to a constituent material such as SiO ₂ and an etchant which is not sufficiently low or sufficiently low with respect to, for example, SiN as a constituent material of the etching stop layer and the etching protection wall 12 is used. Can be used. When a photoresist is used as the constituent material of the etching protection wall 12, BHF (buffered hydrofluoric acid) can be used as the etching solution for forming the cavity 13.

  In the above-described example, the etching protective material constituting the etching protective wall 12 is a photoresist layer or SiN by plasma CVD when the sacrificial layer 6 is silicon oxide. However, the etching protective material is not limited to this. Is not to be done. Any material can be used as long as it is resistant to the etchant of the sacrificial layer 6 and can satisfactorily fill the groove 11 at a temperature that does not damage the metal hybrid war (generally 400 ° C. or lower). In an inorganic system, it can be made of amorphous silicon by plasma CVD.

  In the above example, the substrate 1 is a silicon substrate. However, the present invention is not limited to the above example, for example, a substrate in which a semiconductor layer is formed on an insulating or semi-insulating substrate can be used. However, various modifications and changes can be made.

A and B are schematic cross-sectional views of respective manufacturing steps of an example of a method for manufacturing an electronic circuit device mixed with a micromachine according to the present invention. A and B are schematic cross-sectional views of respective manufacturing steps of an example of a method for manufacturing an electronic circuit device mixed with a micromachine according to the present invention. A and B are schematic cross-sectional views of respective manufacturing steps of an example of a method for manufacturing an electronic circuit device mixed with a micromachine according to the present invention. A and B are schematic cross-sectional views of respective manufacturing steps of an example of a method for manufacturing an electronic circuit device mixed with a micromachine according to the present invention. A and B are schematic cross-sectional views of respective manufacturing steps of another example of the method for manufacturing a micromachine mixed electronic circuit device according to the present invention. A and B are schematic cross-sectional views of respective manufacturing steps of another example of the method for manufacturing a micromachine mixed electronic circuit device according to the present invention. A and B are schematic cross-sectional views of respective manufacturing steps of another example of the method for manufacturing a micromachine mixed electronic circuit device according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Circuit element, 3 ... Element isolation insulating layer, 4 ... Etching stop layer, 5 ... Conductive pattern, 5i ... Input signal line, 5o ... Output signal line, 6 ... Sacrificial Layer 6a... Opening, 7... Micromachine operating structure, 8... Wiring portion, 9... Wiring interlayer insulating layer, 9 d. ...... groove, 12a ... etching opening, 12 ... etching protection wall, 12M ... etching protection material layer, 13 ... cavity, 17 ... micromachine mixed electronic circuit device, 18 ... contact window, 19 ... ... Passivation film, 20 ... Recess, 22 ... Opening, 23 ... Protective film, 51, 52 ... Terminal pattern

Claims (2)

A micromachine mixed electronic circuit device in which a micromachine element and an electronic circuit are mixedly mounted on a common substrate,
An electronic circuit element formed in the electronic circuit forming part on the substrate;
A wiring part formed on the electronic circuit forming part and having a multilayer wiring pattern laminated via a wiring interlayer insulating layer;
Corresponding to the formation part of the micromachine element of the substrate, a cavity part formed in the wiring interlayer insulating layer continuous with the wiring interlayer insulating film,
An etching protective wall disposed on the inner wall surface of the cavity of the wiring interlayer insulating layer;
A micromachine element comprising a conductive pattern and a micromachine operation structure portion formed on the substrate in the cavity portion and located at a lower position than the uppermost wiring pattern of the wiring portion;
An etching stop layer disposed under the conductive pattern of the micromachine element,
The micromachine element is an electronic circuit mixed with a micromachine, characterized in that the entire outer surface other than the mechanical support portion of the micromachine operation structure portion is exposed and held in a non-contact state with the other portion in the cavity portion. apparatus. A method of manufacturing a micromachine mixed electronic circuit device in which a micromachine element and an electronic circuit are mixedly mounted on a common substrate,
A first step of forming an electronic circuit element on the electronic circuit forming portion on the substrate;
A second step of forming an etching stop layer on a formation portion of the micromachine element on the substrate and forming a conductive pattern of the micromachine element on the etching stop layer;
A third step of forming a sacrificial layer in the formation portion of the micromachine element on the conductive pattern;
A fourth step of forming on the sacrificial layer a micromachine operation structure portion in which the mechanical operation of the micromachine element is performed;
A fifth step of performing a heat treatment for activating the conductive pattern and the micromachine operating structure;
A wiring part in which a multilayer wiring pattern is laminated via a wiring interlayer insulating layer is formed on the electronic circuit forming part, and the micromachine operation structure part is embedded on the micromachine element forming part. A sixth step of forming only the wiring interlayer insulating layer;
A seventh step of digging a groove in the wiring interlayer insulating layer at a predetermined distance from the micromachine operation structure portion between at least the micromachine operation structure and at least the electronic circuit portion;
An eighth step of forming an etching protective wall by filling the groove with an etching resistant material;
Forming an opening in the wiring interlayer insulating layer to expose the micromachine operation structure, and etching and removing the sacrificial layer under the micromachine operation structure.
The placement portion of the micromachine operation structure portion is formed with a cavity portion in which the entire outer surface other than the mechanical support portion of the micromachine operation structure portion maintains a non-contact state with the other portions. A method of manufacturing an electronic circuit device mixed with a micromachine.

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