JP2012166313A - Method for manufacturing vertical comb actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a comb electrode structure with high alignment accuracy.SOLUTION: Comb electrode mask patterns 152a and 152b are formed on a surface 151a of a silicon substrate 151, and a silicon substrate 153 is stuck via these patterns. Rough comb mask patterns 154 and 155 including comb electrode mask patterns 152a and 152b are formed in a surfaces 151b and 153b of the silicon substrates 151 and 153. DRIE (Deep Reactive Ion Etching) is executed from the surface 153b side, the silicon substrate 153 is selectively removed by using the rough comb mask pattern 155 as a mask, and the silicon substrate 151 is selectively removed by using the comb electrode mask pattern 152a as a mask. The DRIE is executed from the surface 151b side, a remaining silicon substrate 151c is selectively removed by using the rough comb mask pattern 154 as a mask, and a remaining silicon substrate 153c is selectively removed by using the comb electrode mask pattern 152b as a mask.

Description

  The present invention relates to a method of manufacturing a vertical comb electrostatic actuator that drives a structure manufactured by a micromachining technique with static electricity.

  One of electrostatic drive actuators manufactured using micromachining technology is a vertical electrostatic comb actuator. In the vertical electrostatic comb actuator, a pair of opposing comb electrodes are arranged in a step in a direction perpendicular to the extending direction, and electrostatic is applied between the comb electrodes according to the applied voltage between the comb electrodes. An attractive force is generated, and one of the comb electrodes is moved in the vertical direction. Recently, various proposals have been made for actuators such as micromirrors.

  In order to obtain a desired driving characteristic in the vertical comb actuator, a fixed comb electrode (hereinafter referred to as a fixed lower comb electrode) and a movable comb electrode (hereinafter referred to as a movable) among the opposing vertical comb electrodes. A high alignment accuracy is required between the upper comb electrodes).

  To meet the above-mentioned alignment accuracy requirements, either a method of bonding two substrates in which a fixed lower comb electrode and a movable upper comb electrode constituting a vertical comb electrode are formed as separate substrates, or from both sides of a single substrate A method of directly forming a comb electrode by photolithography and substrate etching has been proposed. However, in any method, the alignment accuracy between the comb electrodes in the bonding process and the photolithography process depends on the alignment function and performance of the manufacturing apparatus to be used. It is positioned as an important issue.

  In response to the above problem, US Pat. No. 6,713,367 discloses a method for comb-tooth processing on a surface of a bonded substrate after bonding a partially etched substrate and another substrate. A method has been proposed in which a vertical comb electrode is formed in a self-aligned manner by patterning an etching mask in a lump and performing vertical etching on the etching mask from one direction so as to penetrate the bonded substrate.

  Hereinafter, the prior art will be specifically described with reference to FIGS. 6 and 7a to 7e.

  FIG. 6 is a schematic cross-sectional view of a vertical comb actuator. The vertical comb actuator includes a fixed lower comb electrode 62 mechanically coupled to a support substrate 60 via an insulating film 61 and a movable upper comb electrode 63. The fixed lower comb electrode 62 and the movable upper comb electrode 63 are arranged stepwise in the vertical direction. 7a to 7e show the steps of the conventional method for manufacturing the vertical comb actuator of FIG. First, as shown in FIG. 7 a, an SOI (Silicon On Insulator) substrate 70 composed of a support layer 71, a buried oxide film 72, and an active layer 73 is etched and processed by using a rough comb-tooth mask pattern 74 as a mask. Comb electrodes 75 are formed. Next, as shown in FIG. 7b, a silicon substrate 76 is bonded to this structure. Subsequently, as shown in FIG. 7c, comb electrode mask patterns 77a and 77b are collectively formed using a single layer photomask. Subsequently, as shown in FIG. 7d, the silicon substrate 76 and the coarse comb mask pattern 74 are etched with respect to the comb electrode mask patterns 77a and 77b, thereby forming the comb electrode mask pattern 74a. Further, the coarse fixed lower comb electrode 75 is continuously vertically etched with respect to the comb electrode mask pattern 74a to form the fixed lower comb electrode 75a, the unnecessary region 78a, and the movable upper comb electrode 78b.

  Here, in the vertical etching process, it is required to process the dimension defined by the ratio of the distance G and the depth D shown in FIG.

  Subsequently, as shown in FIG. 7e, the comb-shaped electrode mask patterns 77a, 77b, 74a and the unnecessary region 78a are removed by etching to form the movable upper comb-shaped electrode 78b and the fixed lower comb-shaped electrode 75a.

US Pat. No. 6,713,367

  According to the above-described manufacturing method, the alignment between the fixed lower comb electrode and the movable upper comb electrode constituting the vertical comb electrode is determined by a single layer mask. High alignment accuracy regardless of performance.

  However, it is difficult to manufacture a desired comb-tooth structure due to problems that occur in the subsequent silicon vertical processing step.

  Hereinafter, the problem will be described. In FIG. 7d, the silicon vertical etching to be processed with respect to the comb-tooth electrode mask patterns 77a and 77b is generally performed by DRIE (Deep Reactive Ion Etching). In the fine vertical comb electrode structure as shown in FIG. 7d, the aspect ratio D / G at the time of silicon etching reaches about 10. For example, when the comb tooth interval G is 3 μm and the total comb tooth thickness D is 30 μm, the aspect ratio is 10. In other words, the DRIE silicon vertical etching process requires that a dimension with an aspect ratio of 10 be vertically processed with high accuracy. In other words, a highly difficult manufacturing technique is required.

  In the case of performing DRIE silicon vertical etching with an aspect ratio of about 10, it is well known that the defect shown in FIG. 8 occurs as the etching progresses, that is, as the etching depth increases.

  For example, as indicated by reference numeral 81 in FIG. 8, the verticality of the shape is lost, and the index θ shifts from the ideal state θ = 0 degrees to either the positive (+) negative (−) direction, or As indicated by reference numeral 82 in FIG. 8, there is a problem that the processing side surface is roughened, or as indicated by reference numeral 83 in FIG. 8, silicon that is not removed from the etching bottom remains as a columnar residue. Regarding the silicon columnar residue, when the mask pattern 77a for the comb electrode shown in FIG. 7d is continuously vertically etched up to the rough fixed comb electrode 75, the vicinity of the side bottom surface of the fixed lower comb electrode 75a is obtained. Occurs.

  In particular, as shown in FIG. 7d, in the silicon vertical etching to be processed for the comb electrode mask patterns 77a and 77b, the silicon substrate 76 is etched and the exposed rough comb mask pattern 74 is continuously etched. In order to form a comb-tooth electrode by a complicated manufacturing method in which the rough fixed lower comb-tooth electrode 75 is further etched continuously based on the mask pattern 74a for the comb-tooth electrode transferred by etching here. The defect appears more prominently.

  Any of these processed shape defects hinders the function of the final vertical comb actuator and degrades the performance.

  The present invention has been proposed in view of the above-described circumstances, and its object is to provide a simple manufacturing method capable of manufacturing a vertical comb electrode structure constituting a vertical comb actuator with high alignment accuracy and high processing accuracy. It is to provide.

  The method of manufacturing a vertical comb electrode structure according to the present invention includes a step of forming a comb electrode mask pattern on a first surface of a first semiconductor layer, and the comb electrode mask on the first semiconductor layer. A step of bonding a second semiconductor layer through a pattern, and the comb-shaped electrode on the second surface of the first semiconductor layer opposite to the first surface of the first semiconductor layer. Forming a first coarse comb mask pattern including a first portion of the mask pattern; and a second of the second semiconductor layer disposed to face the first surface of the first semiconductor layer A second portion of the comb electrode mask pattern excluding the first portion of the comb electrode mask pattern is formed on the second surface of the second semiconductor layer opposite to the first surface. The process of forming the second coarse comb-tooth mask pattern to be included and the first etching process And selectively removing the first semiconductor layer by using the first coarse comb mask pattern as a mask and further removing the second semiconductor layer by using the mask pattern for comb electrodes as a mask; Then, a second etching process is performed, the second semiconductor layer is masked using the second coarse comb mask pattern, and the first semiconductor layer is masked using the comb electrode mask pattern as a mask. A step of selectively removing, and a step of removing the comb electrode mask pattern and the first and second coarse comb mask patterns.

  According to the present invention, there is provided a simple manufacturing method capable of manufacturing a vertical comb electrode structure of a vertical comb actuator with high alignment accuracy and high processing accuracy.

It is a schematic perspective view of the optical deflector using the vertical comb-tooth actuator by 1st embodiment. It is drive explanatory drawing of a vertical comb-tooth actuator. The first process of the manufacturing method of the optical deflector of Drawing 1 is shown. FIG. 3B shows a process following FIG. 3A of the method of manufacturing the optical deflector of FIG. FIG. 3B shows a process following FIG. 3B of the method of manufacturing the optical deflector of FIG. FIG. 3C shows a process following FIG. 3C of the method of manufacturing the optical deflector of FIG. 3D shows a process following FIG. 3D of the method of manufacturing the optical deflector of FIG. FIG. 3e shows a process following FIG. 3e of the method of manufacturing the optical deflector of FIG. FIG. 3D shows a final step following FIG. 3F of the method of manufacturing the optical deflector of FIG. 1. It is explanatory drawing for the mask pattern design of 1st embodiment. FIG. 8 shows a process according to a modification that can be applied in place of the processes of FIGS. 3e and 3f. Fig. 4 shows another process applicable in place of the process of Fig. 3c. The mark and opening formation process for visible light alignment which can be additionally applied is shown. It is a schematic perspective view of the optical deflector using the vertical comb actuator by 2nd embodiment. 5 shows a first step of the method for manufacturing the optical deflector of FIG. 5B shows a process following FIG. 5A of the method of manufacturing the optical deflector of FIG. 5B shows a process following FIG. 5B of the method of manufacturing the optical deflector of FIG. FIG. 5c shows a process following FIG. 5c of the method of manufacturing the optical deflector of FIG. 5D shows a process following FIG. 5D of the method of manufacturing the optical deflector of FIG. FIG. 5e shows a process following FIG. 5e of the method of manufacturing the optical deflector of FIG. FIG. 5B shows the last step following FIG. 5F of the method of manufacturing the optical deflector of FIG. It is explanatory drawing for the mask pattern design of 2nd embodiment. FIG. 6 shows another process that can be substituted for the process of FIG. The mark and opening formation process for visible light alignment which can be additionally applied is shown. 6 shows a process corresponding to the process of FIG. 5C in the case where a patterned SOI substrate is applied instead of the SOI substrate of FIG. 5A. It is a cross-sectional schematic diagram of a vertical comb actuator. 7 shows the first step of the conventional manufacturing method of the vertical comb actuator of FIG. FIG. 7B shows a process subsequent to FIG. 7A of the conventional manufacturing method of the vertical comb actuator of FIG. 7 shows a step following FIG. 7 b of the conventional manufacturing method of the vertical comb actuator of FIG. 6. 7 shows a step following FIG. 7 c of the conventional manufacturing method of the vertical comb actuator of FIG. 6. 7 shows the final step following FIG. 7d of the conventional manufacturing method of the vertical comb actuator of FIG. This shows a problem that occurs in the DRIE silicon vertical etching process.

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

<First embodiment>
1, 2 and 3a to 3i show a first embodiment of the present invention. FIG. 1 is a schematic perspective view of an optical deflector using a vertical comb actuator, and FIG. FIG. 3A to FIG. 3I are schematic process explanatory views focusing on the AA ′ cross section of the optical deflector of FIG. 1.

  As shown in FIG. 1, the optical deflector manufactured according to the present embodiment includes a movable substrate 110 and a fixed substrate 120 that are bonded to each other via an insulating layer 130.

  The movable substrate 110 includes a pair of fixed portions 111 fixed to the fixed substrate 120, an optical deflection plate 113 having an optical mirror surface 114, a pair of hinge portions 112 connecting the fixed portion 111 and the optical deflection plate 113, and A movable upper comb electrode 115 extending from the light deflection plate 113 is provided. The hinge portion 112 can be torsionally deformed, and supports the light deflection plate 113 so as to be swingable. The movable substrate 110 is formed from one silicon layer, for example.

  The fixed substrate 120 has a support layer 121 to which the fixed portion 111 of the movable substrate 110 is fixed. The support layer 121 has a notch 123 that provides a space necessary for the light deflection plate 113 and the movable upper comb electrode 115 to swing. The fixed substrate 120 also has a fixed lower comb electrode 122 extending into the notch 123. The fixed substrate 120 is formed from, for example, one silicon layer.

  The movable substrate 110 is disposed so as to overlap the fixed substrate 120. That is, the movable substrate 110 and the fixed substrate 120 are arranged so as to be shifted in the thickness direction thereof. The movable upper comb electrode 115 and the fixed lower comb electrode 122 extend in a staggered manner facing each other, for example, when projected onto the upper surface 124 of the fixed substrate 120, and are shifted in the thickness direction of the movable substrate 110 and the fixed substrate 120. And constitutes a vertical comb actuator.

  The optical deflector also includes a voltage application mechanism 140 that applies an arbitrary voltage between the movable substrate 110 and the fixed substrate 120. When a voltage is applied between the movable substrate 110 and the fixed substrate 120 by the voltage application mechanism 140, an electrostatic attractive force is generated between the movable upper comb electrode 115 and the fixed lower comb electrode 122. As a result, as shown in FIG. 2, the movable upper comb electrode 115 is attracted to the fixed lower comb electrode 122, and the light deflection plate 113 is rotated around the central axis 116 of the hinge portion 112. The angle of this rotation depends on the magnitude of the voltage applied between the movable substrate 110 and the fixed substrate 120. By controlling the magnitude of the applied voltage by the voltage applying mechanism 140, the light reflected by the optical mirror surface 114 of the light deflector plate 113 is deflected in a desired direction.

  In the following, the method of manufacturing the optical deflector shown in FIG. 1 will be described with reference to schematic process explanatory views (FIGS. 3 a to 3 i) focusing particularly on the A-A ′ cross section.

  First, as shown in FIG. 3a, a silicon substrate 151 as a semiconductor layer for forming a fixed lower comb electrode is prepared. The silicon substrate 151 has a thickness necessary for a fixed substrate to be formed later. Silicon substrate 151 is made of, for example, single crystal silicon. However, the silicon substrate 151 is not limited to this, and may be made of, for example, polycrystalline silicon.

  Next, as shown in FIG. 3b, comb electrode mask patterns 152a and 152b for forming a fixed lower comb electrode and a movable upper comb electrode later on the first surface 151a of the silicon substrate 151 are formed. Form. The comb electrode mask patterns 152a and 152b are not limited to this, but are formed of, for example, a silicon oxide film. Specifically, a silicon oxide film having an arbitrary thickness is formed on the silicon substrate 151 by a general thermal oxidation method or a CVD (Chemical Vapor Deposition) method, and then a desired resist patterning is performed by a photolithography process. And unnecessary portions of the oxide film are etched away using the patterned resist as a mask to form comb electrode mask patterns 152a and 152b. For etching removal of the oxide film, a wet method using a chemical solution such as hydrofluoric acid or a dry method using a fluorine-based gas is appropriately selected according to the pattern rule. Both the comb electrode mask patterns 152a and 152b serve as masks for subsequent silicon vertical etching processing, and the pattern processing shape requires high processing accuracy. In particular, the cross-sectional shape of the mask is one of the factors that determine the cross-sectional perpendicularity of silicon etching. Therefore, it is desirable to apply a dry etching technique capable of ensuring high processing accuracy, particularly an RIE (Reactive Ion Etching) technique capable of obtaining cross-sectional perpendicularity, to this oxide film etching removal step.

  Subsequently, as shown in FIG. 3c, a silicon substrate 153 as a semiconductor layer for forming a movable upper comb electrode is formed on the silicon substrate 151 on which the comb electrode mask patterns 152a and 152b are formed. Through the mask patterns 152a and 152b, in other words, the substrate patterns 156 are bonded together by a silicon direct bonding method or the like so that the comb electrode mask patterns 152a and 152b are arranged at the bonding interfaces of the silicon substrates 151 and 153. Form. The silicon substrate 153 is made of, for example, single crystal silicon, and has a thickness necessary for forming a movable upper comb electrode to be formed later.

  Here, the case where the comb electrode mask patterns 152 a and 152 b are formed on the first surface 151 a of the silicon substrate 151 has been described, but the comb electrode mask patterns 152 a and 152 b are not necessarily the first pattern of the silicon substrate 151. It is not necessary to form the first surface 151a, and the first surface of the silicon substrate 153 may be disposed at the bonding interface of the bonded substrate 156, and is disposed so as to face the first surface 151a of the silicon substrate 151. 153a may be formed.

  Furthermore, silicon direct bonding is a technique that allows clean silicon or silicon oxide surfaces to be bonded to each other without using an intermediate adhesive. Generally, strong bonding strength is achieved by high-temperature heat treatment at about 1000 degrees Celsius. Can be secured. Since the bonded structure can be regarded as a single homogeneous silicon substrate, it is excellent in consistency with the manufacturing process shown in this embodiment.

  The comb electrode mask patterns 152a and 152b have a step corresponding to the film thickness at the interface, and depending on the rules such as the mask thickness and the pattern width, there are voids generated at the bonding interface. It may affect later processes. In that case, by applying a damascene process generally performed in a semiconductor process, particularly a multilayer wiring process, as shown in FIG. 3J, the comb-tooth electrode mask pattern 152d is embedded in the silicon substrate 151. , 152c can be formed, and as a result, generation of voids and the like can be prevented during bonding.

  Subsequently, as shown in FIG. 3d, on both surfaces of the bonded substrate 156, that is, the second surface 151b opposite to the first surface 151a of the silicon substrate 151 and the first surface 153a opposite to the first surface 153a of the silicon substrate 153. On the second surface 153b on the side, coarse comb mask patterns 154 and 155 that enclose the previously embedded comb electrode mask patterns 152a and 152b are formed. Here, the coarse comb-tooth mask patterns 154 and 155 include the comb-tooth electrode mask patterns 152a and 152b, for example, when the comb-tooth electrode mask patterns 152a and 152b and the coarse comb-tooth mask patterns 154 and 155 are both silicon substrates. When projected onto the first surface 151a of 151, the comb electrode mask patterns 152a and 152b are included in the regions of the coarse comb mask patterns 154 and 155, in other words, the comb electrode mask pattern 152a. , 152b are located inside the coarse comb-tooth mask patterns 154, 155, respectively. Therefore, of course, the areas of the coarse comb mask patterns 154 and 155 are larger than the areas of the comb electrode mask patterns 152a and 152b.

  The coarse comb mask patterns 154 and 155 are formed of, for example, a silicon oxide film, although not limited thereto. Specifically, first, an arbitrary film thickness is formed on both surfaces of the bonded substrate 156 by a thermal oxidation method or a CVD method. Here, when the thermal oxidation method is selected, it may also serve as an oxidation step during the heat treatment performed in the previous bonding step. Next, desired resist patterning is performed on both surfaces of the bonded substrate 156 on which the oxide film has been formed by a photolithography process, and unnecessary portions of the oxide film are etched away using the patterned resist as a mask, and then the rough comb teeth are formed. Mask patterns 154 and 155 are formed. Here, a wet method or a dry etching method is appropriately selected for the etching removal of the oxide film, but the etching removal process of the oxide film is a dry etching method capable of ensuring high processing accuracy, and in particular, a cross-sectional perpendicularity is obtained. It is desirable to apply the RIE (Reactive Ion Etching) technique.

  In this photolithography process, since alignment with the comb electrode mask patterns 152a and 152b embedded in the interface of the bonded substrate 156 is necessary, infrared light alignment having transparency to silicon is used as a standard. However, a visible light alignment with high versatility is also possible by additionally inserting a process.

  For example, as shown in FIG. 3k, an oxide film pattern 171 as an alignment mark for visible light is formed simultaneously with the formation of the comb electrode mask patterns 152a and 152b, and is oxidized by photolithography and mask etching processes after bonding. A film opening pattern 172 is formed, and an opening 173 is formed in the silicon substrate 153 by a subsequent silicon etching process to expose the oxide film pattern 171, thereby forming a desired visible light alignment mark.

  Here, the photolithography for the oxide film opening pattern 172 needs only to have an alignment accuracy enough to expose the oxide film pattern 171. For example, alignment using a part of the substrate outline such as OF (orientation flat) of the silicon substrate. Is enough.

  According to this method, visible light can be used for photolithography alignment with respect to the oxide film 155 ′ before the formation of the coarse comb mask pattern 155, and high-precision alignment with the comb electrode mask patterns 152 a and 152 b. Is possible. Even when the other coarse comb mask pattern 154 is formed, visible light alignment can be performed by the same processing.

  Subsequently, as shown in FIG. 3E, a silicon vertical etching process 157a is performed on the coarse comb-tooth mask pattern 155 until it passes through the bonded substrate 156. More specifically, the silicon vertical etching process 157a is performed from the second surface 153b side of the silicon substrate 153, and the silicon substrate 153 is selectively removed using the coarse comb-tooth mask pattern 155 as a mask. The silicon substrate 151 is selectively removed by using the exposed comb-tooth electrode mask pattern 152a in addition to the tooth mask pattern 155 as a mask. As a result, a fixed lower comb electrode 158a is formed. Here, the previously embedded comb electrode mask pattern 152a functions as a mask for determining the shape of the fixed lower comb electrode, and the coarse comb mask pattern 154 functions as a stopper film for the silicon vertical etching process 157a. The silicon vertical etching process 157a is performed by, for example, DRIE (Deep Reactive Ion Etching).

  Subsequently, as shown in FIG. 3f, the silicon vertical etching process 157b is performed on the coarse comb mask pattern 155 until it penetrates the bonded substrate 156. More specifically, a silicon vertical etching process 157b is performed from the second surface 151b side of the silicon substrate 151, and the remaining silicon substrate 151c is selectively removed using the coarse comb mask pattern 154 as a mask. The remaining silicon substrate 153c is selectively removed using the comb electrode mask pattern 152b exposed in addition to the comb mask pattern 154 as a mask. As a result, a movable upper comb electrode 158b is formed. Here, the previously embedded comb electrode mask pattern 152b functions as a mask for determining the shape of the movable upper comb electrode, and the coarse comb mask pattern 155 functions as a stopper film for the silicon vertical etching process 157b. The silicon vertical etching process 157b is performed by DRIE, for example.

  Here, the case where the silicon vertical etching process 157b shown in FIG. 3F is performed following the silicon vertical etching process 157a shown in FIG. 3E has been described, but the order of the etching processes is not limited to this. Alternatively, the silicon vertical etching process 157b may be performed prior to the silicon vertical etching process 157a.

  Subsequently, as shown in FIG. 3g, the comb electrode mask patterns 152a and 152b and the coarse comb mask patterns 154 and 155, which function as masks and stoppers in the silicon vertical etching processes 157a and 157b, are removed by etching. Comb electrode 158a and movable upper comb electrode 158b are completed. Here, for etching removal of the oxide film, a wet method using a hydrofluoric acid chemical solution or a dry method using a gas is appropriately selected. Since the wet method may cause sticking when the structure including the movable part is dried, it is preferable to select a dry method using a gas here.

  Subsequently, although not shown in the drawing, metal thin film patterning for the electrode pad and the light deflection plate is performed using a shadow mask or the like. As the metal, gold (Au), aluminum (Al), or the like is appropriately selected depending on the light wavelength range to be deflected.

  Through the above steps, the optical deflector shown in FIG. 1 is completed.

  In the mask pattern design of the first embodiment, as shown in FIG. 3h, R1> F1 between the width R1 of the coarse comb mask patterns 154 and 155 and the width F1 of the comb electrode mask pattern 152b. When there is a relationship, the interval between adjacent coarse comb mask patterns 154 and 155 is ΔR1, and the amounts of protrusion on both the left and right sides of the coarse comb mask pattern 155 with respect to the comb electrode mask pattern 152b are ΔFL1 and ΔFR1, respectively. , ΔR1> 0, ΔFL1> 0, and ΔFR1> 0 may be designed.

  Here, only one of the vertical comb electrodes 158a and 158b, ie, the mask patterns 152b and 155 of the movable upper comb electrode 158b has been described, but the mask patterns 152a and 154 of the fixed lower comb electrode 158a are also described. Based on similar design guidelines.

  The thicknesses of the comb electrode mask patterns 152a and 152b and the coarse comb mask patterns 154 and 155 may be any film thickness considering the resistance to subsequent silicon vertical etching and the stopper resistance. What is necessary is just to determine suitably according to the thickness of a tooth electrode layer, and manufacturing apparatus performance.

  Furthermore, in the present embodiment, the example in which the comb electrode mask patterns 152a and 152b are formed of a silicon oxide film has been described. However, as a mask material, pattern processing is easy, and silicon vertical etching resistance is provided. In addition, the material is not particularly limited as long as process consistency with the bonding step can be obtained. For example, an aluminum film is a material that can be easily patterned and has dry etching resistance, and can be applied by changing the bonding method from direct bonding that requires high-temperature heat treatment to low-temperature bonding that takes into account the heat resistance of the aluminum film. Examples of the low temperature bonding include plasma activated bonding and room temperature bonding by ion irradiation.

  Furthermore, although the silicon vertical etching processes 157a and 157b of the present embodiment have been described as examples using DRIE, the processing method is not limited to DRIE, and any technique capable of vertical silicon processing can be applied. Is possible. For example, silicon crystal anisotropic etching (wet etching) using a difference in etching rate depending on the silicon crystal orientation can be selected. Specifically, crystal anisotropic etching (wet etching) may be performed on a (110) silicon substrate. In addition, processing by photoexcited electrolytic polishing, femtosecond laser, or the like can be appropriately selected.

  As is clear from the above description, according to the first embodiment, the comb teeth alignment is determined by the comb electrode mask patterns 152a and 152b embedded in the bonding interface of the bonded substrate. The alignment accuracy between the tooth electrodes is high, and the aspect ratio (d / g: ratio of opening width g to etching depth d, see FIG. 3f) at the time of silicon vertical etching 157a and 157b is half that of the conventional manufacturing method. Thus, the vertical comb electrode can be formed without causing defects such as poor verticality of the cross section, rough processing side surface, or silicon columnar residue on the bottom surface of the etching, and the vertical comb actuator shown in FIG. The optical deflector using can be realized with a simple and accurate method.

  The first embodiment can be modified. Hereinafter, the modification and its advantages will be described mainly with reference to FIG.

<Modification of First Embodiment>
First, in accordance with the steps shown in FIGS. 3a to 3f, the comb electrode mask patterns 152a and 152b are formed, and then silicon is etched into the comb electrode mask patterns 152a and 152b. As shown in one embodiment.

As a modification, silicon etching processing performed on the comb electrode mask patterns 152a and 152b is not substantially vertical as shown in FIGS. 3e and 3f, but undercut AC _(A) , as shown in FIG. It has AC _(B) , and it is in the point which carries out an etching process on the conditions used as arbitrary inclination | tilt angles ₍ theta _{) (A)} and ₍ theta _{) (B)} , respectively.

Specifically, the DRIE etching conditions are selective with respect to the comb electrode mask patterns 152a and 152b, have undercuts AC _(A) and AC _(B) , and each has an arbitrary Adjustment is made so that the inclination angles θ _(A) and θ _(B) are obtained.

  In general DRIE silicon etching, a protective film forming component and a silicon isotropic etching component are alternately repeated in a time-sharing manner, and a parameter such as time, gas, power, pressure, etc. is adjusted so that a substantially vertical shape is obtained. Etching conditions are set.

  In this modification, the etching conditions 157A and 157B are performed by adjusting and setting the DRIE etching conditions so that the isotropic etching component and the protective film forming component change stepwise as the etching depth increases.

As a result, the comb-tooth electrodes 158A and 158B can be formed in a substantially trapezoidal shape or a substantially triangular shape with AC _(A) = AC _(B) and θ _(A) = θ _(B) .

  In addition to the effects of the first embodiment, the shape obtained by the above steps, that is, the substantially trapezoidal or substantially triangular shape that is vertically symmetrical with respect to the comb electrode mask patterns 152a and 152b, It has the advantage that it contributes to the improvement of actuator drive characteristics.

<Second embodiment>
4 and 5a to 5h show a second embodiment of the present invention. FIG. 4 is a schematic perspective view of an optical deflector using a vertical comb actuator, and FIG. 5 is shown in FIG. It is schematic process explanatory drawing which paid its attention to the AA 'cross section especially of an optical deflector.

  As shown in FIG. 4, the optical deflector manufactured according to this embodiment includes a movable substrate 210, a fixed substrate 220, and a support substrate 232 that are bonded to each other via an insulating layer 230. The movable substrate 210 and the fixed substrate 220 are bonded to each other via the insulating layer 230, and the fixed substrate 220 and the support substrate 232 are bonded to each other via the insulating layer 234.

  The movable substrate 210 includes a pair of fixed portions 211 fixed to the fixed substrate 220, an optical deflection plate 213 provided with an optical mirror surface 214, a pair of hinge portions 212 connecting the fixed portion 211 and the optical deflection plate 213, and A movable upper comb electrode 215 extending from the light deflection plate 213 is provided. The hinge part 212 can be torsionally deformed, and supports the light deflection plate 213 so as to be swingable. The movable substrate 210 is formed from one silicon layer, for example.

  The fixed substrate 220 has a support layer 221 to which the fixed portion 211 of the movable substrate 210 is fixed. The support layer 221 has a notch 223 that provides a space necessary for the light deflection plate 213 and the movable upper comb electrode 215 to swing. The fixed substrate 220 also has a fixed lower comb electrode 222 extending into the notch 223. The fixed substrate 220 is formed from, for example, one silicon layer.

  The movable substrate 210 is disposed so as to overlap the fixed substrate 220. That is, the movable substrate 210 and the fixed substrate 220 are arranged so as to be shifted in the thickness direction thereof. The movable upper comb electrode 215 and the fixed lower comb electrode 222 are alternately extended opposite to each other in the projection onto the upper surface 224 of the fixed substrate 220, for example, and shifted in the thickness direction of the movable substrate 210 and the fixed substrate 220. And constitutes a vertical comb actuator.

  The optical deflector also includes a voltage application mechanism 240 that applies an arbitrary voltage between the movable substrate 210 and the fixed substrate 220. When a voltage is applied between the movable substrate 210 and the fixed substrate 220 by the voltage application mechanism 240, an electrostatic attractive force is generated between the movable upper comb electrode 215 and the fixed lower comb electrode 222. As a result, the movable upper comb electrode 215 is attracted to the fixed lower comb electrode 222, and the light deflection plate 213 is rotated around the central axis of the hinge portion 212. The angle of this rotation depends on the magnitude of the voltage applied between the movable substrate 210 and the fixed substrate 220. By controlling the magnitude of the applied voltage by the voltage applying mechanism 240, the light reflected by the optical mirror surface 214 of the light deflecting plate 213 is deflected in a desired direction.

  A feature of the second embodiment is that the support substrate 232 facilitates a wafer level manufacturing process regardless of the thicknesses of the movable upper comb electrode 215 and the fixed lower comb electrode 222. A method for manufacturing the optical deflector will be described with reference to FIGS.

  First, as shown in FIG. 5a, an SOI (Silicon On Insulator) substrate 250 is prepared as a swing-out substrate. Here, the SOI substrate 250 is a structure in which a support layer 251 and an active layer 253 are bonded via a buried oxide film 252. For example, the support layer 251 and the active layer 253 are made of single crystal silicon, and the buried oxide film 252 is made of a silicon oxide film. The active layer 253 is a semiconductor layer for forming a fixed lower comb electrode, and has a thickness necessary for the fixed lower comb electrode. The support layer 251 mainly functions as a support substrate necessary for the manufacturing process.

  Next, as shown in FIG. 5b, comb electrode mask patterns 254a and 254b for forming a fixed lower comb electrode and a movable upper comb electrode on the first surface 253a of the active layer 253, and Then, a support layer mask pattern 254c for forming a support layer is formed, and then a silicon substrate 255 thicker than a movable substrate to be formed later is formed on the active layer 253 on which the mask patterns 254a, 254b, and 254c are formed. The mask patterns 254a, 254b, and 254c are bonded so as to be embedded between the active layer 253 and the silicon substrate 255 via the mask patterns 254a, 254b, and 254c. Silicon substrate 255 is made of, for example, single crystal silicon.

  The mask patterns 254a, 254b, and 254c are not limited to this, but are formed of, for example, a silicon oxide film. Specifically, the SOI substrate 250 is formed in an arbitrary film thickness by a general thermal oxidation method or a CVD method, and a desired resist patterning is performed by a subsequent photolithography process, and an unnecessary portion is formed using the patterned resist as a mask. The oxide film is removed by etching to form mask patterns 254a, 254b, and 254c. For removing the oxide film by etching, a wet method or a dry method is appropriately selected according to the pattern rule. The comb electrode mask patterns 254a and 254b are both silicon vertical etching masks, and high patterning accuracy is required for pattern processing. In particular, the cross-sectional shape of the mask is one of the factors that determine the perpendicularity of the silicon etching cross-section. Therefore, it is desirable to apply a dry etching technique capable of ensuring high processing accuracy, particularly an RIE (Reactive Ion Etching) technique capable of obtaining cross-sectional perpendicularity, to this oxide film etching removal step. Subsequently, the silicon substrate 255 is bonded by a technique such as silicon direct bonding, and then the silicon substrate 255 is thinned so as to have a thickness necessary for the movable upper comb electrode. A bonded substrate 257 including a silicon layer 256 as a semiconductor layer for formation is formed. Here, the thinning process is appropriately selected from techniques such as mechanical grinding (Back Grind) or chemical mechanical polishing (Chemical Mechanical Polish).

  Note that the mask patterns 254a, 254b, and 254c have a level difference at the interface, and depending on rules such as the mask thickness and pattern width, voids generated at the bonding interface are later generated. May affect the process. In that case, by applying a damascene process generally used in a semiconductor process, particularly a multilayer wiring process, as shown in FIG. 5i, the mask pattern 254d, 254e and 254f can be formed, and as a result, the problem of gap generation at the time of bonding is solved.

  Although the case where the mask patterns 254a, 254b, and 254c are formed on the first surface 253a of the active layer 253 of the SOI substrate 250 has been described here, the mask patterns 254a, 254b, and 254c are not necessarily formed on the SOI substrate 250. There is no need to do this, and it is only necessary to be disposed at the bonding interface of the bonded substrate 257. Therefore, it may be formed on the first surface 255a of the silicon substrate 255 disposed so as to face the first surface 253a of the active layer 253 of the SOI substrate 250.

  Subsequently, as shown in FIG. 5 c, silicon on the surface of the thinned silicon layer 256, that is, on the opposite side of the first surface 256 a of the silicon layer 256 that coincides with the first surface 255 a of the silicon substrate 255. On the second surface 256b of the layer 256, a coarse comb-tooth mask pattern 258 including the previously embedded comb-tooth electrode mask pattern 254a is formed.

  Although not limited to this, the coarse comb mask pattern 258 is formed of, for example, a silicon oxide film. Specifically, an arbitrary film thickness is formed on the surface of the silicon layer 256 on the bonded substrate 257 including the silicon layer 256 by a thermal oxidation method or a CVD method. Here, when the thermal oxidation method is selected, it may also serve as an oxidation step during the heat treatment performed in the previous bonding step. Subsequently, a desired resist patterning is performed on the surface of the silicon layer 256 on which the oxide film is formed by a photolithography process, an unnecessary portion of the oxide film is etched away using the patterned resist as a mask, and a rough comb mask pattern 258 is formed. Form. For the etching removal of the oxide film, it is desirable to apply a dry etching technique, especially a RIE (Reactive Ion Etching) technique for the same reason as described above.

  In this photolithography process, since alignment with the comb electrode mask patterns 254a and 254b embedded in the bonding interface of the bonded substrate 257 is required, infrared light alignment having transparency to silicon is performed. Although standard, it is possible to perform visible light alignment with high versatility by adding additional processes.

  For example, as shown in FIG. 5j, an oxide film pattern 271 as an alignment mark for visible light is formed simultaneously with the formation of the comb electrode mask patterns 254a and 254b, and is oxidized by photolithography and mask etching processes after bonding. A film opening pattern 272 is formed, and an opening 273 is formed in the silicon layer 256 by a subsequent silicon etching process to expose the oxide film pattern 271, thereby forming a desired visible light alignment mark.

  Here, the photolithography for the oxide film opening pattern 272 only needs to have an alignment accuracy enough to expose the oxide film pattern 271. For example, alignment using a part of the substrate outer shape such as OF (orientation flat) of the silicon substrate. Is enough.

  According to this method, visible light can be used for photolithography alignment with respect to the oxide film 258 ′ before the formation of the coarse comb mask pattern 258, and high-precision alignment with respect to the comb electrode mask patterns 254a and 254b. Is possible.

  Subsequently, as shown in FIG. 5d, an opening mask pattern 259 is formed on the surface of the support layer 251 by a photolithography process, and the oxide film 252 performs DRIE silicon etching on the support layer 251 using the opening mask pattern 259 as a mask. Repeat until exposed. The support substrate 260 is formed by this etching. The exposed buried oxide film 252 is subjected to photolithography and oxide film etching to form a coarse comb mask pattern 261 including the buried comb electrode mask pattern 254b.

  Here, in the photolithography process for forming the coarse comb mask pattern 261, the support layer 251 is opened and the exposed oxide film 252 needs to be patterned. However, a general semiconductor process such as spin coating cannot be applied to resist coating necessary for photolithography. Accordingly, a spray coating method in which a mist resist is sprayed to form a film on the substrate, or an electrodeposition resist method using an electroless plating technique is appropriately selected. Further, since the subsequent pattern exposure needs to be performed on the etching bottom surface including the step, a projection exposure machine having a long focal depth is appropriately selected.

  Although the etching opening of the support layer 251 has been described by DRIE, wet etching with an alkaline chemical solution may be selected. In the case of an alkaline chemical solution, TMAH (tetramethylammonium aqueous solution), KOH (potassium hydroxide), or the like can be used. When wet etching is selected, an opening mask pattern 259 is formed from a resist and a thermal oxidation method having alkali resistance. Or an oxide film formed by a CVD method.

  Subsequently, as shown in FIG. 5E, a silicon vertical etching process 264a is performed on the coarse comb mask pattern 258 formed on the second surface 256b of the silicon layer 256 until it penetrates the bonded silicon layer 263. More specifically, a silicon vertical etching process 264a is performed from the second surface 256b side of the silicon layer 256, and the silicon layer 256 is selectively removed using the coarse comb-tooth mask pattern 258 as a mask. The active layer 253 is selectively removed using the exposed comb-tooth electrode mask pattern 254a in addition to the tooth mask pattern 258 as a mask. As a result, a fixed lower comb electrode 265a is formed. Here, the previously embedded comb electrode mask pattern 254a functions as a mask for determining the shape of the fixed lower comb electrode, and the coarse comb mask pattern 261 functions as a stopper film for the silicon vertical etching process 264a. The support layer mask pattern 254c functions as a mask for leaving a necessary support layer. The silicon vertical etching process 264a is performed by DRIE, for example.

  Subsequently, as shown in FIG. 5f, the silicon vertical etching is performed until the coarse comb-tooth mask pattern 261 formed at the bottom of the support layer 251 etched by the opening mask pattern 259 penetrates the bonded silicon layer 263. Processing 264b is performed. More specifically, a silicon vertical etching process 264b is performed from the second surface 253b side of the active layer 253, and the exposed residual active layer 253c is selectively removed using the coarse comb mask pattern 261 as a mask. The exposed residual silicon layer 256c is selectively removed using the exposed comb-tooth electrode mask pattern 254b in addition to the coarse comb-tooth mask pattern 261 as a mask. As a result, the movable upper comb electrode 265b is formed. Here, the previously embedded comb electrode mask pattern 254b functions as a mask for determining the movable upper comb electrode shape, and the coarse comb mask pattern 258 functions as a stopper film for the silicon vertical etching process 264b. The silicon vertical etching process 264a is performed by DRIE, for example.

  Here, the previously embedded comb electrode mask pattern 254b functions as a mask for determining the movable upper comb electrode shape, and the coarse comb mask pattern 258 functions as a stopper film for the silicon vertical etching process 264b.

  Here, the case where the silicon vertical etching process 264b shown in FIG. 5f is performed following the silicon vertical etching process 264a shown in FIG. 5e has been described. However, the order of the etching processes is not limited to this. Alternatively, the silicon vertical etching process 264b may be performed prior to the silicon vertical etching process 264a.

  Subsequently, as shown in FIG. 5g, the mask patterns 254a, 254b, 254c, 258, 261, and 259 functioning as masks and stoppers in the silicon vertical etching processes 264a and 264b are removed by etching, and the vertical comb electrodes 265b and 265a are removed. The support substrate 260 is completed. Here, for etching removal of the oxide film, a wet method using a hydrofluoric acid chemical solution or a dry method using a gas is appropriately selected. Since the wet method may cause sticking when the structure including the movable part is dried, it is desirable to apply a dry method using a gas here.

  Subsequently, although not shown in the drawing, metal thin film patterning for the electrode pad and the light deflection plate is performed using a shadow mask or the like. As the metal, gold (Au), aluminum (Al), or the like is appropriately selected depending on the light wavelength range to be deflected.

  The optical deflector shown in FIG. 4 is completed through the above steps.

  In the second embodiment, as shown in FIG. 5k, instead of the SOI substrate 250, a patterned SOI substrate 280 may be used as a swing-out substrate. Here, the patterned SOI substrate 280 is a structure in which the support layer 281 and the active layer 283 are bonded via the buried oxide film 282 already patterned into the mask patterns 282a and 282b. By using the patterned SOI substrate 280, there is no need to use a dedicated manufacturing apparatus described in FIG. 5d, that is, a dedicated manufacturing apparatus such as a spray coating machine, an electrodeposition resist film forming machine, or a long focal depth exposure machine. In addition to improving processing accuracy, it has the advantage that it can contribute to the provision of inexpensive elements, such as being capable of being processed and manufactured with a typical manufacturing apparatus.

  Further, regarding the mask pattern design of the second embodiment, as shown in FIG. 5h, the opening width K of the opening mask pattern 259, the width R2 of the coarse comb mask pattern 258, and the comb electrode mask pattern 254b. The relation of K> R2> F2 with the width F2, and the interval between adjacent coarse comb mask patterns 258 and 261 is ΔR2, and the coarse comb mask pattern 258 with respect to the comb electrode mask pattern 254b When the amounts of protrusion on the left and right sides are ΔFL2 and ΔFR2, respectively, the mask pattern may be designed so as to have a relationship of ΔR2> 0, ΔFL2> 0, ΔFR2> 0.

  Here, only one of the vertical comb electrodes 265a and 265b, that is, the mask patterns 254b and 258 of the movable upper comb electrode 265b has been described, but the mask patterns 254a and 261 of the fixed lower comb electrode 265a are also described. Based on similar design guidelines.

  The comb electrode mask patterns 254a and 254b and the coarse comb mask patterns 258 and 261 may have any thickness in consideration of the resistance to the subsequent silicon vertical etching and the stopper resistance. What is necessary is just to determine suitably according to the thickness of a tooth electrode layer, and manufacturing apparatus performance.

  Further, in the present embodiment, the example in which the comb electrode mask patterns 254a and 254b are formed of a silicon oxide film has been described. However, as a mask material, pattern processing is easy and silicon vertical etching resistance is provided. In addition, the material is not particularly limited as long as process consistency with the bonding method can be obtained. For example, an aluminum film is a material that is easy to pattern and has dry etching resistance, and can be applied by changing the bonding method from direct bonding that requires high-temperature heat treatment to low-temperature bonding that takes into account the heat resistance of the aluminum film. . Examples of the low temperature bonding include plasma activated bonding and room temperature bonding by ion irradiation.

  Furthermore, although the silicon vertical etching processing 264a and 264b of the present embodiment has been described as an example using DRIE, the processing method is not limited to DRIE, and can be applied to any technology capable of vertical silicon processing. It is. For example, silicon crystal anisotropic etching (wet etching) using a difference in etching rate depending on the silicon crystal orientation can be selected. Specifically, crystal anisotropic etching (wet etching) may be performed on a (110) silicon substrate. In addition, processing by photoexcited electrolytic polishing, femtosecond laser, or the like can be appropriately selected.

  Furthermore, in the present embodiment, the description has been given by using the SOI substrate 250 in which the active layer 253 is to be a fixed comb electrode as a swing out later, but the movable comb electrode side may be swing out as an SOI substrate.

  The total thickness of the comb-tooth silicon layer is at most 100 microns even if the two layers are combined, and a fragile structure is created in the process. It is difficult to maintain a level of rigidity. As a measure to avoid such difficulties, as a process handling method for thinned wafers, a dedicated support substrate is attached to the thinned substrate with an adhesive or the like, and each manufacturing process is passed in that state, and the dedicated support substrate is attached in the final process. The method of peeling is well known.

  However, it is difficult to apply to a fragile structure such as the optical deflector described in the first embodiment due to a structure damage problem in the final peeling process.

  In that respect, by adding a support layer using an SOI substrate as shown in the second embodiment, even a fragile structure represented by an optical deflector or the like can maintain rigidity at the wafer level until the final stage of the manufacturing process. I get out. Therefore, it can be processed by a general-purpose manufacturing apparatus without worrying about damage to the structure, and in addition to realizing high-precision processing, low-cost manufacturing of the element is possible.

  As apparent from the above description, according to the second embodiment, the comb teeth alignment is determined by the comb electrode mask patterns 254a and 254b embedded in the bonding interface of the bonded substrate. The alignment accuracy between the electrodes is high, and the aspect ratio of the silicon vertical etching process 264a, 264b is halved compared to the conventional manufacturing method, the verticality of the cross section, the roughness of the processing side surface, the silicon columnar residue on the bottom surface of the etching, etc. The optical deflector using the vertical comb actuator shown in FIG. 4 is combined with the effect of the first embodiment in which the vertical comb electrode can be easily formed at the wafer level without causing the above problems. Can be realized by a simple manufacturing method.

  In addition, about the deformation | transformation form (FIG. 3i) of 1st embodiment, it is applicable also in this 2nd embodiment.

  As described above, in the first embodiment and the second embodiment, the optical deflector has been described. However, the present invention is not limited to the optical deflector, and an acceleration sensor having a vertical comb actuator manufactured by a micromachining technique or Applicable to all micro devices such as gyro sensors.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to these embodiments, and various modifications and changes can be made without departing from the scope of the present invention. Also good. The various modifications and changes described here include an implementation in which the above-described embodiments are appropriately combined.

DESCRIPTION OF SYMBOLS 60 ... Support substrate, 61 ... Insulating film, 62 ... Fixed lower comb electrode, 63 ... Movable upper comb electrode, 70 ... SOI substrate, 71 ... Support layer, 72 ... Embedded oxide film, 73 ... Active layer, 74 ... Coarse Comb mask pattern, 74a ... Comb electrode mask pattern, 75 ... Fixed lower comb electrode, 75a ... Fixed lower comb electrode, 76 ... Silicon substrate, 77a ... Comb electrode mask pattern, 77b ... Comb electrode Mask pattern, 78a ... unnecessary region, 78b ... movable upper comb electrode, 110 ... movable substrate, 111 ... fixed portion, 112 ... hinge portion, 113 ... light deflector, 114 ... optical mirror surface, 115 ... movable upper comb electrode, DESCRIPTION OF SYMBOLS 116 ... Center axis, 120 ... Fixed substrate, 121 ... Support layer, 122 ... Fixed lower comb electrode, 123 ... Notch part, 124 ... Upper surface, 130 ... Insulating layer, 140 ... Voltage application mechanism, 151 ... Silicon substrate, 151 ... first surface, 151b ... second surface, 151c ... residual silicon substrate, 152a ... comb electrode mask pattern, 152b ... comb electrode mask pattern, 152c ... comb electrode mask pattern, 152d ... comb teeth Electrode mask pattern, 153... Silicon substrate, 153 a... First surface, 153 b... Second surface, 153 c... Residual silicon substrate, 154... Mask pattern, 154. Coarse comb mask pattern, 155 '... oxide film, 156 ... bonded substrate, 157A ... etching process, 157B ... etching process, 157a ... vertical silicon etching process, 157b ... vertical silicon etching process, 158A ... comb tooth electrode, 158B ... Comb electrode, 158a ... Fixed lower comb electrode, 158a ... Vertical comb electrode, 1 8b ... movable upper comb electrode, 158b ... vertical comb electrode, 171 ... oxide film pattern, 172 ... oxide film opening pattern, 173 ... opening, 210 ... movable substrate, 211 ... fixed part, 212 ... hinge part, 213 ... light Deflection plate, 214 ... optical mirror surface, 215 ... movable upper comb electrode, 220 ... fixed substrate, 221 ... support layer, 222 ... fixed lower comb electrode, 223 ... notch, 224 ... upper surface, 230 ... insulating layer, 232 ... support substrate, 234 ... insulating layer, 240 ... voltage application mechanism, 250 ... SOI substrate, 251 ... support layer, 252 ... oxide film, 252 ... buried oxide film, 253 ... active layer, 253a ... first surface, 253b ... Second surface, 253c ... exposed remaining active layer, 254a ... comb electrode mask pattern, 254b ... comb electrode mask pattern, 254c ... support layer mask pattern, 254d ... Mask pattern, 254e ... Mask pattern, 254f ... Mask pattern, 255 ... Silicon substrate, 255a ... First surface, 256 ... Silicon layer, 256a ... First surface, 256b ... Second surface, 256c ... Exposed residual silicon layer 257 ... Bonded substrate, 258 ... Coarse comb mask pattern, 258 '... Oxide film, 259 ... Opening mask pattern, 260 ... Support substrate, 261 ... Coarse comb mask pattern, 263 ... Bonded silicon layer, 264a ... Silicon Vertical etching process, 264b ... Silicon vertical etching process, 265a ... Fixed lower comb electrode, 265b ... Movable upper comb electrode, 271 ... Oxide film pattern, 272 ... Oxide film opening pattern, 273 ... Opening, 280 ... Patterned SOI substrate , 281 ... support layer, 282 ... buried oxide film, 282a ... mask pattern 282b ... mask pattern, 283 ... the active layer.

Claims (9)

A method of manufacturing a vertical comb electrode structure,
Forming a comb electrode mask pattern on the first surface of the first semiconductor layer;
Bonding the second semiconductor layer to the first semiconductor layer via the comb electrode mask pattern;
A first coarse comb including a first portion of the mask pattern for the comb-tooth electrode on a second surface of the first semiconductor layer opposite to the first surface of the first semiconductor layer; Forming a tooth mask pattern;
On the second surface of the second semiconductor layer opposite to the first surface of the second semiconductor layer disposed to face the first surface of the first semiconductor layer, the comb teeth Forming a second coarse comb mask pattern including a second portion of the comb electrode mask pattern excluding the first portion of the electrode mask pattern;
Perform a first etching process to select the first semiconductor layer using the first coarse comb mask pattern as a mask and the second semiconductor layer using the comb electrode mask pattern as a mask Removing it automatically,
Perform a second etching process to select the second semiconductor layer using the second coarse comb mask pattern as a mask and the first semiconductor layer using the comb electrode mask pattern as a mask. Removing it automatically,
A method of manufacturing a vertical comb electrode structure, comprising the step of removing the comb electrode mask pattern and the first and second coarse comb mask patterns.   2. The method of manufacturing a vertical comb electrode structure according to claim 1, wherein each of the first and second semiconductor layers is made of single crystal silicon.   At least one of the first and second semiconductor layers is composed of an active layer of an SOI substrate, and one of the first and second coarse comb mask patterns is formed on a buried oxide film of the SOI substrate. The method of manufacturing a vertical comb electrode structure according to claim 1, wherein:   2. The method of manufacturing a vertical comb electrode structure according to claim 1, wherein the bonding of the first and second semiconductor layers is performed by direct silicon bonding.   2. The method of manufacturing a vertical comb electrode structure according to claim 1, wherein the first and second etching processes are performed by DRIE.   2. The method of manufacturing a vertical comb electrode structure according to claim 1, wherein the first and second etching processes are performed by crystal anisotropic etching.   7. The method of manufacturing a vertical comb electrode structure according to claim 6, wherein the first and second semiconductor layers are formed of a (110) silicon substrate.   2. The method of manufacturing a vertical comb electrode structure according to claim 1, wherein the comb electrode mask pattern and the first and second coarse comb electrode mask patterns are formed of a silicon oxide film.   2. The method of manufacturing a vertical comb electrode structure according to claim 1, wherein the comb electrode mask pattern and the first and second coarse comb electrode mask patterns are formed of an aluminum film.

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