JP2006276872A - Method of manufacturing micromirror element and micromirror element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a micromirror element having a thin torsion bar having a more accurate thickness while being accurately located at the middle in the thickness direction of a material substrate, and to provide a micromirror element of such kind. <P>SOLUTION: In manufacturing a micromirror element which is provided with a mirror forming part, a frame part, and a torsion bar on the material substrate 8 having a layer structure including a plurality of silicon layers 20 and 21 and at least an intermediate layer 160, a process in which a pretorsion bar T' which is thinner than the mirror forming part and in contact with the intermediate layer, at least a part of the mirror forming part connected to the pretosion bar T', and at last a part of the frame part connected to the pretorsion bar T' are formed, and a process in which the torsion bar T is formed by removing the intermediate layer 160 connected to the pretorsion bar T', are performed on a silicone layer 20 by etching the silicon layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is an element incorporated in an optical switching device that switches an optical path between a plurality of optical fibers, an optical disc device that performs data recording / reproduction processing on an optical disc, and the like, and changes the light path direction. The present invention relates to a micromirror element used for the above.

  In recent years, optical communication technology has been widely used in various fields. In optical communication, an optical signal is transmitted using an optical fiber as a medium. In order to switch the transmission path of the optical signal from one fiber to another, a so-called optical switching device is generally used. Characteristics required for an optical switching device to achieve good optical communication include large capacity, high speed, and high reliability in the switching operation. From these viewpoints, as an optical switching device, there is an increasing expectation for a device incorporating a micromirror element manufactured by a micromachining technique. According to the micromirror element, it is possible to perform a switching process between an optical transmission line on the input side and an optical transmission line on the output side in the optical switching device without converting the optical signal into an electrical signal. This is because it is suitable for obtaining the above-mentioned characteristics.

  An optical switching device using a micromirror element manufactured by a micromachining technique is described in, for example, Patent Document 1 and Non-Patent Document 1 below.

International Publication No. 00/20899 pamphlet “Fully Provisioned 112 × 112 Micro-Mechanical Optical Crossconnect with 35.8Tb / sec Demonstrated Capacity” Proc. 25th Optical Fiber Communication Conf. Baltimore. PD12 (2000)

  FIG. 39 shows a schematic configuration of a general optical switching device 200. The optical switching device 200 includes a pair of micromirror arrays 201 and 202, an input fiber array 203, and an output fiber array 204. The input fiber array 203 includes a predetermined number of input fibers 203a, and the micromirror array 201 is provided with micromirror elements 201a so as to correspond to the input fibers 203a. Similarly, the output fiber array 204 includes a predetermined number of output fibers 204a, and the micromirror array 202 is provided in the micromirror array 202 so as to correspond to each output fiber 204a. A plurality of microlenses 205 are arranged so as to face the end portions of the respective input fibers 203a, and a plurality of microlenses 206 are arranged so as to face the end portions of the respective output fibers 204a.

  At the time of optical transmission, the light L1 emitted from the input fiber 203a passes through the corresponding microlens 205 to become parallel light and is emitted toward the micromirror array 201. The light L1 is reflected by the corresponding micromirror element 201a and deflected to the micromirror array 202. At this time, the micromirror element 201a inclines the mirror surface or reflection surface so that the light L1 enters the desired micromirror element 202a. Next, the light L 1 is reflected by the micromirror element 202 a and deflected to the output fiber array 204. At this time, the micromirror element 202a tilts the mirror surface so that the light L1 is incident on the desired output fiber 204a.

  Thus, according to the optical switching device 200, the light L1 emitted from each input fiber 203a is connected to the desired output fiber 204a on a one-to-one basis by the deflection in the micromirror arrays 201 and 202. And the output fiber 204a which the light L1 reaches | attains is switched by changing suitably the deflection angle in micromirror element 201a, 202a.

  FIG. 40 shows a schematic configuration of another general optical switching device 300. The optical switching device 300 includes a micro mirror array 301, a fixed mirror 302, and an input / output fiber array 303. The input / output fiber array 303 includes a predetermined number of input fibers 303a and a predetermined number of output fibers 303b, and the micromirror array 301 is provided with micromirror elements 301a so as to correspond to the fibers 303a and 303b. Yes. A plurality of microlenses 304 are arranged so as to face the ends of the respective fibers 303a and 303b.

  At the time of optical transmission, the light L2 emitted from the input fiber 303a is emitted toward the micromirror array 301 via the microlens 304. The light L2 is reflected to the fixed mirror 302 by being reflected by the corresponding first micromirror element 301a, reflected by the fixed mirror 302, and then incident on the second micromirror element 301a. At this time, the first micromirror element 301a tilts the mirror surface so that the light L2 is incident on the desired second micromirror element 301a. Next, the light L2 is reflected to the input / output fiber array 303 by being reflected by the second micromirror element 301a. At this time, the second micromirror element 301a tilts the mirror surface so that the light L2 enters the desired output fiber 303b.

  Thus, according to the optical switching device 300, the light L2 emitted from each input fiber 303a is connected to the desired output fiber 303b on a one-to-one basis by the deflection in the micromirror array 301 and the fixed mirror 302. Then, by appropriately changing the deflection angle in the first and second micromirror elements 301a, the output fiber 303b to which the light L2 reaches is switched.

  In an optical switching device that reflects and deflects light using a micromirror element, such as the optical switching devices 200 and 300, the structure of the micromirror element affects the overall performance of the optical switching device, such as switching accuracy and switching speed. give. Further, when the control method for the tilt angle of the mirror surface is determined by the structure of the micromirror element, the control accuracy can be improved if the control method can be simplified. Furthermore, the simplification of the control method can reduce the burden on the control drive circuit and reduce the overall size of the optical switching device. In addition, the optical monitoring method and the crosstalk suppression method can be simplified.

  FIG. 41 is a partially omitted exploded perspective view of a micromirror element 400 which is an example of a conventional biaxial micromirror element incorporated in the optical switching devices 200 and 300 and the like. The micromirror element 400 has a structure in which a mirror substrate 410 and a base substrate 420 are laminated via a spacer portion (not shown). The mirror substrate 410 includes a mirror forming portion 411, an inner frame 412, and an outer frame 413. The mirror forming portion 411 and the inner frame 412 are connected by a pair of torsion bars 414. The inner frame 412 and the outer frame 413 are connected by a pair of torsion bars 415. The pair of torsion bars 414 defines the rotation axis of the rotation operation of the mirror forming portion 411 relative to the inner frame 412. The pair of torsion bars 415 defines the rotation axis of the rotation operation of the inner frame 412 and the mirror forming portion 411 accompanying the outer frame 413.

  A pair of flat plate electrodes 411a and 411b are provided on the back surface of the mirror forming portion 411, and a mirror surface (not shown) for reflecting light is provided on the front surface. A pair of flat plate electrodes 412 a and 412 b are provided on the back surface of the inner frame 412.

  The base substrate 420 is provided with flat plate electrodes 420 a and 420 b so as to face the flat plate electrodes 411 a and 411 b of the mirror forming portion 411, and the flat plate electrodes so as to face the flat plate electrodes 412 a and 412 b of the inner frame 412. 420c and 420d are provided. In the conventional micromirror element 400, a method of generating an electrostatic force using such a plate electrode is generally employed as a driving method.

  According to such a configuration, for example, when the flat plate electrode 420a of the base substrate 420 is negatively charged in a state where the flat plate electrode 411a of the mirror forming portion 411 is positively charged, the gap between the flat plate electrode 411a and the flat plate electrode 420a is obtained. Electrostatic attractive force is generated in the mirror, and the mirror forming portion 411 swings or rotates in the direction of the arrow M3 while twisting the pair of torsion bars 414.

  On the other hand, for example, when the flat plate electrode 420c of the base substrate 420 is negatively charged in a state where the flat plate electrode 412a of the inner frame 412 is positively charged, an electrostatic attractive force is generated between the flat plate electrode 412a and the flat plate electrode 420c. The inner frame 412 swings or rotates in the direction of the arrow M4 while twisting the pair of torsion bars 415 with the mirror forming portion 411. FIG. 42 shows a state in which the inner frame 412 and the accompanying mirror forming portion 411 are rotated to the inclination angle θ with respect to the outer frame 413 by such rotation driving.

  The orientation of the plate electrodes 411a and 411b with respect to the plate electrodes 420a and 420b differs between the state shown in FIG. 41 and the state shown in FIG. Therefore, in each state shown in FIG. 41 and FIG. 42, even if the same voltage is applied between the flat plate electrode 411a and the flat plate electrode 420a, for example, the magnitude of the electrostatic attractive force generated is different. The angle of inclination of the mirror forming portion 411 with respect to is different. Therefore, in each state shown in FIG. 41 and FIG. 42, in order to make the inclination angle of the mirror forming portion 411 with respect to the inner frame 412 the same, for example, between the plate electrode 411a and the plate electrode 420a, an appropriate A large amount of electrostatic attraction must be generated. In order to achieve this, it is necessary to control the voltage applied to the plate electrode 411a and the plate electrode 420a in consideration of the inclination angle of the inner frame 412 with respect to the outer frame 413.

  In order to perform such control of the applied voltage, the tilt angle data for the inner frame 412 and the tilt angle data for the outer frame 413 of the mirror forming unit 411 with respect to the applied voltage are stored, and these are referred to. A method such as selecting an applied voltage must be employed. In addition, the amount of data is enormous. Therefore, in the micromirror element 400 that employs such a driving method with applied voltage control, it is difficult to improve the switching speed, and the burden on the driving circuit increases, which is not preferable.

  Further, in the flat plate electrode structure adopted in the micromirror element 400, the mirror forming portion 411 including the flat plate electrodes 411a and 411b by the flat plate electrodes 420a, 420b, 420c and 420d provided on the base substrate 420, In addition, since the inner frame 412 having the plate electrodes 412a and 412b is driven to be pulled in, a pull-in voltage is present in the driving. That is, a phenomenon that the mirror forming portion 411 or the inner frame 412 is suddenly pulled in at a certain voltage may occur, and a problem that the tilt angle of the mirror forming portion 411 cannot be appropriately controlled may occur. This problem is particularly noticeable when a large inclination angle (about 5 ° or more) is to be achieved, that is, when the torsion bar has a large degree of twist.

  As a means for solving this problem, a method of driving a micromirror element by a comb electrode structure instead of a plate electrode structure has been proposed. FIG. 43 is a partially omitted perspective view of a micromirror element 500 employing a comb electrode structure. The micromirror element 500 includes a mirror forming portion 510 having a mirror surface (not shown) on the upper surface or the lower surface, an inner frame 520, and an outer frame 530 (partially omitted). Are integrally formed. Specifically, the mirror forming portion 510 is formed with a pair of first comb electrodes 510a and 510b at opposite ends thereof. The inner frame 520 is formed with a pair of second comb electrodes 520a and 520b extending inward corresponding to the first comb electrodes 510a and 510b, and a pair of third comb electrodes 520c and 520d. Is formed to extend outward. A pair of fourth comb electrodes 530a and 530b are formed on the outer frame 530 so as to extend inward corresponding to the third comb electrodes 520c and 520d. The mirror forming portion 510 and the inner frame 520 are connected by a pair of torsion bars 540, and the inner frame 520 and the outer frame 530 are connected by a pair of torsion bars 550. The pair of torsion bars 540 define the rotation axis of the rotation operation of the mirror forming portion 510 with respect to the inner frame 520, and the pair of torsion bars 550 rotate the inner frame 520 with respect to the outer frame 530 and the accompanying mirror forming portion 510. Specifies the rotational axis of operation.

  In the micromirror element 500 having such a configuration, a pair of comb electrodes, for example, the first comb electrode 510a and the second comb electrode 520a, which are provided close to each other in order to generate an electrostatic force, At the time of application, as shown in FIG. 44 (a), the state is divided into two upper and lower stages. When a voltage is applied, as shown in FIG. 44B, the first comb electrode 510a is drawn into the second comb electrode 520a, thereby driving the mirror forming portion 510. More specifically, in FIG. 43, for example, when the first comb electrode 510a is positively charged and the second comb electrode 520a is negatively charged, the mirror forming unit 510 twists the pair of torsion bars 540. While rotating in the direction of M5. On the other hand, when the third comb electrode 520c is positively charged and the fourth comb electrode 530a is negatively charged, the inner frame 520 rotates in the direction of M6 while twisting the pair of torsion bars 550.

  These two rotational movements are independent of each other. That is, before applying potential to the first comb-tooth electrodes 510a and 510b and the second comb-tooth electrodes 520a and 520b, the second comb-tooth electrode 520a regardless of the inclination angle of the inner frame 520 with respect to the outer frame 530. , 520b always have the same orientation of the first comb electrodes 510a, 510b. As described above, since the tilt angle of the inner frame 520 and the accompanying mirror forming portion 510 with respect to the outer frame 530 is not affected, the control of the tilt angle of the mirror forming portion 510 can be simplified. Further, according to the comb electrode structure, the direction of action of the generated electrostatic force can be set so as to be substantially orthogonal to the rotation direction of the mirror forming portion 510. Therefore, no pull-in voltage exists when the mirror forming unit 510 is driven, and as a result, a large tilt angle can be appropriately achieved for the mirror forming unit 510.

  In the micromirror element 500, the comb teeth, which are electrodes, are displaced with the rotation of the mirror forming portion 510 and the inner frame 520, and therefore have a sufficient thickness corresponding to the inclination angle of the mirror forming portion 510 and the inner frame 520. It is necessary to form a comb electrode. For example, when the length D of the body portion 511 of the mirror forming portion 510 is 1 mm, the mirror forming portion 510 is inclined by 5 ° around the rotation axis defined by the pair of torsion bars 540 with respect to the inner frame 520. Then, one of the body end portions 511 ′ sinks by 44 μm. Therefore, the thickness T of the first comb electrodes 510a and 510b formed on the mirror forming portion 510 needs to be at least 44 μm.

  On the other hand, from the viewpoint of obtaining a large inclination angle with a small applied voltage, the torsion bars 540 and 550 are preferably formed thin. However, in the conventional micromirror element 500, the torsion bars 540 and 550 are formed to have the same thickness as the material substrate constituting the mirror forming portion 510, the inner frame 520, and the outer frame 530, and are thick. For example, if the thickness T of the first comb electrodes 510a and 510b is designed to be 44 μm or more as described above, the thickness of the torsion bars 510a and 510b is designed to be 44 μm or more together with the mirror forming portion 510. With such thick torsion bars 540 and 550, the electrostatic force to be generated between the comb-teeth electrodes in order to twist them increases, and as a result, the drive voltage also increases. Conventionally, the torsion resistance of the torsion bars 540 and 550 is adjusted by changing the width dimension of the torsion bars 540 and 550, but an appropriate torsion resistance is set only by changing the design in the width direction. It may not be enough to do.

  The present invention has been conceived under such circumstances, and it is an object of the present invention to solve or alleviate the above-mentioned conventional problems, and is a micro having a thin torsion bar formed with high accuracy. It aims at providing the manufacturing method of a mirror element, and the micromirror element manufactured by this.

  According to the first aspect of the present invention, a micromirror element including a mirror forming portion, a frame portion, and a torsion bar is manufactured on a material substrate having a laminated structure including a plurality of silicon layers and at least one intermediate layer. This is a method for forming a pre-torsion bar that is thinner than the mirror forming part and in contact with the intermediate layer by etching the silicon layer, and the intermediate layer in contact with the pre-torsion bar is removed. And a step of forming a torsion bar.

  According to such a configuration, the thin torsion bar can be formed with high accuracy at an intermediate position in the thickness direction of the material substrate. Specifically, since the intermediate layer is provided at an intermediate position in the material substrate, the silicon layer in contact with the intermediate layer is etched through the appropriate mask to reach the intermediate layer. A pre-torsion bar made of a silicon layer material is formed at an intermediate position of the material substrate. The pre-torsion bar is formed with dimensions corresponding to the final torsion bar, ie, thickness, width, and length. This pre-torsion bar can be formed thinner than other parts, for example, the mirror forming part, the frame part, and these comb electrode parts. Pretension bar is formed compared to the case where the silicon layer is etched from both sides of the material substrate where the intermediate layer is not present because it is formed by etching using the intermediate layer provided in advance. Higher accuracy can be achieved in terms of position and in particular thickness dimensions. Then, by removing the intermediate layer in contact with the pre-torsion bar, a thin torsion bar having a more accurate thickness dimension while being accurately positioned in the middle of the thickness direction of the material substrate is completed.

  According to a second aspect of the present invention, there is provided another method for manufacturing a micromirror device comprising a mirror forming part, a frame part, and a torsion bar. In this method, a first silicon layer in a first material substrate having a laminated structure of a first silicon layer having a thickness corresponding to the torsion bar, a second silicon layer, and an intermediate layer therebetween is applied to the torsion bar. Forming a pre-torsion bar in contact with the intermediate layer by performing a first etching process up to the intermediate layer through a first mask pattern having a portion for masking a portion to be processed; A step of forming a second material substrate with a built-in pre-torsion bar by bonding a third silicon layer to the silicon layer, and a portion corresponding to the pre-torsion bar with respect to the second silicon layer as a non-mask region A step of performing the second etching process up to the intermediate layer through the second mask pattern including the pre-torsion for the third silicon layer. A step of performing a third etching process until the pre-torsion bar is exposed through a third mask pattern including a portion corresponding to the bar in the non-mask region, and a fourth step with respect to the intermediate layer exposed by the second etching process. And a step of forming a torsion bar by removing an intermediate layer in contact with the pre-torsion bar by performing an etching process. Even with such a configuration, for the same reason as described above with respect to the first side surface, a thin-walled torsion bar having a more accurate thickness dimension while being accurately positioned in the middle of the thickness direction of the material substrate is formed. The

  In the second aspect of the present invention, preferably, a fourth mask pattern for masking the pre-torsion bar after forming the pre-torsion bar on the first material substrate and before forming the second material substrate. Forming a step. According to such a configuration, it is possible to appropriately prevent the exposed pre-torsion bar from being erroneously etched in the above-described third etching process.

  According to a third aspect of the present invention, there is provided another method for manufacturing a micromirror device comprising a mirror forming part, a frame part, and a torsion bar. In this method, a first silicon layer in a first material substrate having a laminated structure of a first silicon layer having a thickness corresponding to the torsion bar, a second silicon layer, and an intermediate layer therebetween is applied to the torsion bar. Forming a first mask pattern having a portion for masking a portion to be processed, joining a third silicon layer to the first silicon layer, and forming a torsion bar on the second silicon layer A step of performing the first etching process up to the intermediate layer through the second mask pattern including the region to be formed in the non-mask region, and the region where the torsion bar is formed on the third silicon layer as the non-mask region The second etching process is performed until the first mask pattern and the intermediate layer are exposed through the third mask pattern included in Forming the torsion bar; and removing the intermediate layer in contact with the pre-torsion bar by performing a third etching process on the intermediate layer exposed by the first etching process, and forming the torsion bar. It is characterized by including. Even with such a configuration, for the same reason as described above with respect to the first side surface, a thin-walled torsion bar having a more accurate thickness dimension while being accurately positioned in the middle of the thickness direction of the material substrate is formed. The

  According to a fourth aspect of the present invention, there is provided another method for manufacturing a micromirror device comprising a mirror forming part, a frame part, and a torsion bar. This method includes, in a non-mask region, a region where a torsion bar is formed with respect to the first silicon layer in the material substrate having a stacked structure of the first silicon layer, the second silicon layer, and an intermediate layer therebetween. Performing a first etching process up to the intermediate layer through the first mask pattern, forming a groove in the first silicon layer, forming a silicon-based material in the groove, A step of performing a second etching process up to the intermediate layer through a second mask pattern having a portion for masking a portion where a torsion bar is formed with respect to the silicon layer, and being exposed by the second etching process Performing a third etching process on the intermediate layer from the second silicon layer side to the silicon-based material formed in the groove, and a third etching process A step of forming a pre-torsion bar made of a silicon-based material in contact with the intermediate layer by removing the more exposed silicon-based material by a fourth etching process from the second silicon layer side, and an intermediate in contact with the pre-torsion bar Forming a torsion bar by removing the layer. Even with such a configuration, for the same reason as described above with respect to the first side surface, a thin-walled torsion bar having a more accurate thickness dimension while being accurately positioned in the middle of the thickness direction of the material substrate is formed. The

  According to a fifth aspect of the present invention, there is provided another method for manufacturing a micromirror device comprising a mirror forming portion, a frame portion, and a torsion bar. This method includes, in a non-mask region, a region where a torsion bar is formed with respect to a first silicon layer in a material substrate having a stacked structure of a first silicon layer, a second silicon layer, and an intermediate layer therebetween. By performing a first etching process up to the intermediate layer through the first mask pattern, a step of forming a groove in the first silicon layer, a step of forming a silicon-based material on the groove, and a step of A second etching process is performed on the deposited silicon-based material through the second mask pattern having a portion for masking a portion to be processed into a torsion bar until the intermediate layer is reached. A step of forming a pre-torsion bar made of a silicon-based material in contact with the layer; A third etching process up to the intermediate layer through a third mask pattern included in the region, and a fourth etching process performed on the intermediate layer exposed by the third etching process, whereby a pre-torsion bar And a step of forming a torsion bar by removing an intermediate layer in contact with the substrate. Even with such a configuration, for the same reason as described above with respect to the first side surface, a thin-walled torsion bar having a more accurate thickness dimension while being accurately positioned in the middle of the thickness direction of the material substrate is formed. The

  According to a sixth aspect of the present invention, there is provided another method for manufacturing a micromirror device comprising a mirror forming part, a frame part, and a torsion bar. In this method, a first etching process is performed on a first material substrate made of a first silicon layer through a first mask pattern including a region where a torsion bar is formed in a non-mask region. Forming a groove on the material substrate; forming an intermediate layer material on the groove; depositing a silicon-based material on the formed intermediate layer material so as to fill the groove; By creating a second material substrate having a stacked structure of one material substrate, an intermediate layer covering the groove of the first material substrate, and a second silicon layer in contact with the intermediate layer, the second material substrate is being incorporated. A step of forming a pre-torsion bar made of a silicon-based material in contact with the intermediate layer, and a second mask pattern including a portion corresponding to the pre-torsion bar in the non-mask region with respect to the first silicon layer. A second etching process until the intermediate layer material deposited in the groove is exposed, and a third mask pattern including a portion corresponding to the pre-torsion bar in the non-mask region with respect to the second silicon layer A step of performing the third etching process until the intermediate layer is exposed through the intermediate layer, the intermediate layer material exposed by the second etching process, and the fourth etching process on the intermediate layer exposed by the third etching process And removing the intermediate layer material in contact with the pre-torsion bar and the intermediate layer to form the torsion bar. Even with such a configuration, for the same reason as described above with respect to the first side surface, a thin-walled torsion bar having a more accurate thickness dimension while being accurately positioned in the middle of the thickness direction of the material substrate is formed. The

  According to a seventh aspect of the present invention, there is provided another method for manufacturing a micromirror device comprising a mirror forming part, a frame part, and a torsion bar. In this method, a depth corresponding to the thickness of the torsion bar is provided via the first mask pattern having a portion for masking a portion to be processed into the torsion bar with respect to the first material substrate made of the first silicon layer. A first etching process, a first material substrate, an intermediate layer in contact with the etched surface of the first material substrate, and a second material substrate having a stacked structure of a second silicon layer in contact with the intermediate layer. A step of forming, a step of performing a second etching process on the second silicon layer through the second mask pattern including a portion to be processed into a torsion bar in the non-mask region to the intermediate layer, By performing a third etching process on one silicon layer through a third mask pattern that includes a portion to be processed into a torsion bar in a non-mask region, Forming a pre-torsion bar in contact with the layer and performing a fourth etching process on the intermediate layer exposed by the second etching process to remove the intermediate layer in contact with the pre-torsion bar and form the torsion bar And a process. Even with such a configuration, for the same reason as described above with respect to the first side surface, a thin-walled torsion bar having a more accurate thickness dimension while being accurately positioned in the middle of the thickness direction of the material substrate is formed. The

  According to an eighth aspect of the present invention, there is provided another method for manufacturing a micromirror device comprising a mirror forming part, a frame part, and a torsion bar. This method is for masking a portion to be processed into a torsion bar with respect to a first silicon layer in a material substrate having a laminated structure of a first silicon layer, a second silicon layer, and an intermediate layer therebetween. Performing a first etching process to a depth corresponding to the thickness of the torsion bar via the first mask pattern and a second mask pattern including a portion to be processed into a torsion bar in a non-mask region; Removing the pattern; forming a pre-torsion bar in contact with the intermediate layer by performing a second etching process on the first silicon layer through the second mask pattern until reaching the intermediate layer; With respect to the second silicon layer, the intermediate layer is reached via the third mask pattern including the portion corresponding to the pre-torsion bar in the non-mask region. A step of performing a third etching process, and a step of removing the intermediate layer in contact with the pre-torsion bar by performing a fourth etching process on the intermediate layer exposed by the third etching process, and forming a torsion bar , Including. Even with such a configuration, for the same reason as described above with respect to the first side surface, a thin-walled torsion bar having a more accurate thickness dimension while being accurately positioned in the middle of the thickness direction of the material substrate is formed. The

  According to a ninth aspect of the present invention, there is provided another method for manufacturing a micromirror device comprising a mirror forming part, a frame part, and a torsion bar. The method includes a first silicon layer, a second silicon layer having a thickness corresponding to a torsion bar, a third silicon layer, a first intermediate layer between the first silicon layer and the second silicon layer, and a second silicon layer. A first mask pattern for masking a portion to be processed into a torsion bar with respect to the first silicon layer in the material substrate having a laminated structure of a second intermediate layer between the first silicon layer and the third silicon layer; and a torsion bar A step of performing a first etching treatment to a depth corresponding to the thickness of the torsion bar through a second mask pattern including a portion to be processed into a non-mask region, a step of removing the first mask pattern, By performing a second etching process on the silicon layer through the second mask pattern to reach the first intermediate layer, the first silicon layer on the first intermediate layer is formed. Forming a third mask pattern in the first layer and performing a third etching process on the first intermediate layer exposed by the second etching process up to the second silicon layer through the third mask pattern. Thus, the step of forming the fourth mask pattern in the first intermediate layer on the second silicon layer, and the second silicon layer exposed by the third etching process, the second mask layer via the fourth mask pattern. By performing the fourth etching process up to the intermediate layer, a step of forming a pre-torsion bar sandwiched between the first intermediate layer and the second intermediate layer, and the third silicon layer correspond to the pre-torsion bar. A step of performing a fifth etching process up to the second intermediate layer through a fifth mask pattern including a portion in a non-mask region, and exposure by the fifth etching process By performing a sixth etching process on the second intermediate layer and the first intermediate layer on the pre-torsion bar, the first intermediate layer and the second intermediate layer in contact with the pre-torsion bar are removed to remove the torsion bar Forming the step. Even with such a configuration, a thin torsion bar having a more accurate thickness dimension is formed while being positioned accurately in the middle of the thickness direction of the material substrate for the same reason as described above with respect to the first side surface. Is done. In particular, according to the ninth aspect, since the thickness of the torsion bar finally formed is defined by the first and second intermediate layers provided in advance in the material substrate, the thickness of the torsion bar is higher. Accuracy can be achieved.

  In the eighth and ninth aspects of the present invention, the comb electrode portion in the mirror forming portion and / or the frame portion can be formed by the second etching process. Alternatively, the comb-shaped electrode portion in the mirror forming portion and / or the frame portion can be formed by an etching process different from the second etching process.

  According to a tenth aspect of the present invention, there is provided another method for manufacturing a micromirror device comprising a mirror forming portion, a frame portion, and a torsion bar. The method includes a first silicon layer, a second silicon layer having a thickness corresponding to a torsion bar, a third silicon layer, a first intermediate layer between the first silicon layer and the second silicon layer, and a second silicon layer. With respect to the first silicon layer in the material substrate having a stacked structure of the second intermediate layer between the first silicon layer and the third silicon layer, the first mask pattern including a region in which a torsion bar is formed in the non-mask region via the first mask pattern A step of performing a first etching process up to the first intermediate layer, and a second mask pattern for masking a portion to be processed into a torsion bar are formed on the first intermediate layer exposed by the first etching process. A step of performing a second etching process on the first intermediate layer through the second mask pattern up to the second silicon layer, and removing the first mask pattern. Performing a third etching process on the second silicon layer through the first intermediate layer exposed by removing the first mask pattern to reach the second intermediate layer, and A step of forming a pre-torsion bar in contact with the second intermediate layer, and the third silicon layer is reached through a third mask pattern including a portion corresponding to the pre-torsion bar in the non-mask region with respect to the third silicon layer. A pre-torsion bar by performing a fifth etching process on the step of performing the fourth etching process until the second intermediate layer exposed by the fourth etching process and the first intermediate layer on the pre-torsion bar. Removing the first intermediate layer and the second intermediate layer in contact with each other to form a torsion bar. Even with such a configuration, a thin torsion bar having a more accurate thickness dimension is formed while being positioned accurately in the middle of the thickness direction of the material substrate for the same reason as described above with respect to the first side surface. Is done. In particular, according to the tenth aspect, as described above with respect to the ninth aspect, the thickness of the torsion bar that is finally formed is defined by the first and second intermediate layers previously provided in the material substrate. As a result, higher accuracy can be achieved with respect to the thickness of the torsion bar.

  In the first to tenth aspects of the present invention, preferably, inductively coupled plasma etching that performs etching in a high-density plasma is employed as a means for etching the silicon layer. Thereby, highly anisotropic etching can be performed satisfactorily. The frame portion includes a first frame and a second frame, and the torsion bar includes a frame torsion bar connecting the first frame and the second frame, and a biaxial micromirror element is manufactured.

  According to an eleventh aspect of the present invention, a micromirror element is provided. The micromirror element includes a mirror forming portion, a frame portion having a laminated structure including a plurality of silicon layers and at least one intermediate layer, and a thinner wall than the mirror forming portion. A torsion bar that defines a rotation axis for rotation and at least one end connected to a portion of the silicon layer in contact with the intermediate layer.

  The micromirror element having such a configuration can be manufactured by the methods according to the first to tenth aspects of the present invention. Therefore, according to the eleventh aspect of the present invention, the same effects as described above with respect to the first aspect of the present invention can be achieved in the manufacturing process.

  In the eleventh aspect of the present invention, preferably, the frame portion has a first frame and a second frame, and the torsion bar is in contact with the intermediate layer in the silicon layer of the first frame, and the silicon layer of the second frame. By being connected to a portion in contact with the intermediate layer, a biaxial micromirror element is configured.

  Preferably, the frame portion has two intermediate layers, and at least one end of the torsion bar is connected to a portion of the silicon layer between the two intermediate layers in contact with the two intermediate layers. The micromirror element having such a configuration can be manufactured by the methods according to the ninth and tenth aspects of the present invention. Therefore, according to such a configuration, the same effects as described above with respect to the ninth and tenth aspects of the present invention can be achieved.

  Preferably, the frame portion has a first frame and a second frame, and the torsion bar has a portion in contact with the two intermediate layers in the silicon layer between the two intermediate layers of the first frame and the two frames of the second frame. It connects with the site | part which contact | connects two intermediate | middle layers in the silicon | silicone layer between intermediate | middle layers. According to such a configuration, even in the biaxial micromirror element, the same effect as described above with respect to the ninth and tenth aspects of the present invention is exhibited.

  Preferably, the mirror forming portion has a first comb electrode portion, and the frame portion has a second comb tooth for displacing the mirror forming portion by generating an electrostatic force between the frame portion and the first comb electrode portion. By having an electrode part, it is comprised as a comb-tooth-type micromirror element. The first frame has a third comb electrode part, and the second frame is for displacing the first frame and the mirror forming part by generating an electrostatic force between the first frame and the third comb electrode part. By having the fourth comb electrode portion, the biaxial micromirror element is configured as a comb electrode type.

  In the first to eleventh aspects of the present invention, preferably, in the present invention, the intermediate layer provided between the silicon layers is made of an insulating material, thereby efficiently separating each silicon layer. It can be achieved well.

  1 and 2 show a micromirror element 100 according to a first embodiment of the present invention. FIG. 1A is a top view of the micromirror element 100, and FIG. 1B is a bottom view. 2A to 2C are cross-sectional views taken along line AA, line BB, and line CC in FIG. 1, respectively.

  As shown in FIG. 1, the micromirror element 100 includes a mirror forming portion 110, an inner frame 120 surrounding the mirror forming portion 110, an outer frame 130 surrounding the inner frame 120, and a pair of torsion bars that connect the mirror forming portion 110 and the inner frame 120. 140, a pair of torsion bars 150 that connect the inner frame 120 and the outer frame 130 are provided. The pair of torsion bars 140 defines a rotation axis X <b> 1 of the rotation operation of the mirror forming unit 110 with respect to the inner frame 120. The pair of torsion bars 150 defines a rotation axis X2 of the rotation operation of the inner frame 120 and the mirror forming portion 110 with respect to the outer frame 130 and accompanying this. In the present embodiment, the rotation axis X1 and the rotation axis X2 are substantially orthogonal. The micromirror element 100 is integrally formed of a conductive material except for a mirror surface 111 and an insulating layer 160 described later. As the conductive material, a material obtained by doping silicon or polysilicon with an n-type impurity such as P or As or a p-type impurity such as B is used.

  As shown in FIG. 1A, the mirror forming portion 110 has a mirror surface 111 formed as a thin film on its upper surface. Further, first comb electrodes 110 a and 110 b are extended and formed on two opposite side surfaces of the mirror forming portion 110.

  As shown in FIGS. 1B and 2, the inner frame 120 has a laminated structure including an inner frame main part 121, a pair of electrode bases 122, and an insulating layer 160 therebetween. The inner frame main part 121 and the electrode base 122 are electrically separated by the insulating layer 160. The insulating layer 160 is made of silicon oxide such as silicon oxide grown by thermal oxidation on the surface of the silicon-based material. The pair of electrode bases 122 are integrally formed with second comb-teeth electrodes 122a and 122b extending inward, and the inner frame main portion 121 has third comb-teeth extending outward. The electrodes 121a and 121b are integrally formed. As shown in FIG. 2A, the second comb electrodes 122a and 122b are positioned below the first comb electrodes 110a and 110b of the mirror forming unit 110, but during the rotation operation of the mirror forming unit 110. In FIG. 2, the teeth of the first comb electrodes 110a and 110b and the teeth of the second comb electrodes 122a and 122b are shifted from each other as shown in FIG. Is arranged.

  As shown in FIG. 2B, each of the pair of torsion bars 140 is thinner than the mirror forming portion 110 and is connected to the mirror forming portion 110 and the inner frame main portion 121.

  As shown in FIG. 2A, the outer frame 130 has a laminated structure including a first outer frame portion 131, a second outer frame portion 132, and an insulating layer 160 therebetween. The first outer frame portion 131 and the second outer frame portion 132 are electrically separated. As shown in FIG. 1B, the second outer frame 132 is provided with a first island 133, a second island 134, a third island 135, and a fourth island 136 through a gap. ing. As clearly shown in FIGS. 2B and 2C, the first island 133 and the third island 135 are integrally formed with fourth comb electrodes 132a and 132b extending inward, respectively. It is molded into. The fourth comb electrodes 132a and 132b are positioned below the third comb electrodes 121a and 121b of the inner frame main part 121, respectively, but when the inner frame 120 is rotated, the third comb electrodes 121a. , 121b and the teeth of the fourth comb electrodes 132a, 132b are arranged so that the teeth of each other are displaced.

  As shown in FIG. 2A, the pair of torsion bars 150 are connected to a portion in contact with the insulating layer 160 in the inner frame main portion 121 and a portion in contact with the insulating layer 160 in the first outer frame portion 131. ing.

  In the present embodiment, when a potential is applied to the first outer frame portion 131, the first outer frame portion 131 is integrally formed of the same silicon-based material as can be understood with reference to FIG. The first comb electrodes 110a and 110b and the third comb electrodes 121a and 121b are at the same potential through the torsion bar 150, the inner frame main portion 121, the torsion bar 140, and the mirror forming portion 110. In this state, a desired potential is applied to the second comb-tooth electrode 122a or the second comb-tooth electrode 122b, and between the first comb-tooth electrode 110a and the second comb-tooth electrode 122a, or the first comb-tooth electrode 110b. By generating an electrostatic force between the second comb electrode 122b and the second comb electrode 122b, the mirror forming part 110 can be swung around the rotation axis X1. Further, a desired potential is applied to the fourth comb electrode 132a or the fourth comb electrode 132b, and between the third comb electrode 121a and the fourth comb electrode 132a, or between the third comb electrode 121b and the second comb electrode 121b. By generating an electrostatic force between the four comb electrodes 132b, the inner frame 120 and the mirror forming part 110 can be swung around the rotation axis X2.

  3 to 7 show a series of steps in the micromirror element manufacturing method according to the second embodiment of the present invention. This method is one method for forming the above-described micromirror element 100 by micromachining technology. 3 to 7, from the viewpoint of simplification, a process of forming the mirror forming portion M, the torsion bar T, and the pair of comb electrodes E1 and E2 is mainly represented by one cross section. The one cross section is obtained by modeling a plurality of predetermined cross sections in a material substrate on which micromachining is performed. Specifically, the mirror forming unit M represents a partial cross section of the mirror forming unit 110, the torsion bar T represents the cross section of the torsion bars 140 and 150, and the comb electrode E1 represents the first comb electrode. 110a, 110b and a part of the cross section of the second comb electrode 122a, 122b, and a part of the cross section of the third comb electrode 121a, 121b and the fourth comb electrode 132a, 132b by the comb electrode E2. Represents. Also, the cross-sectional views in FIGS. 3 to 7 are upside down from the cross-sectional view in FIG.

  In the manufacture of the micromirror element 100, first, as shown in FIG. 3A, a first SOI (Silicon on Insulator) wafer 1 is prepared as a substrate. The first SOI wafer 1 has a laminated structure including a relatively thin first silicon layer 11, a thick second silicon layer 12, and an insulating layer 160 as an intermediate layer sandwiched between them. The first silicon layer 11 is made of silicon or polysilicon imparted with conductivity by doping an n-type impurity such as P or As. The second silicon layer 12 is made of silicon imparted with conductivity by doping an n-type impurity such as P or As. However, p-type impurities such as B may be used for providing the conductivity. The insulating layer 160 is made of silicon oxide grown on the surface of the first silicon layer 11 or the second silicon layer 12 by a thermal oxidation method. As a film forming means for the insulating layer 160, a CVD method may be employed instead of the thermal oxidation method. After the formation and growth of the insulating layer 160, the first silicon layer 11 and the second silicon layer 12 are bonded to form the first SOI wafer 1. In the present embodiment, the thickness of the first silicon layer 11 is 5 μm, the thickness of the second silicon layer 12 is 100 μm, and the thickness of the insulating layer 160 is 1 μm.

  Next, an oxide film made of silicon oxide is grown on the second silicon layer 12 by a thermal oxidation method, and this is patterned to form an oxide film pattern 51 as shown in FIG. As an etchant for patterning the oxide film, for example, buffered hydrofluoric acid (manufactured by Daikin Industries) made of hydrofluoric acid and ammonium fluoride can be used. This can also be used for the subsequent patterning of the oxide film. The oxide film pattern 51 is for masking portions of the second silicon layer 12 that are processed into the comb-tooth electrode E2 and the frame. More specifically, the oxide film pattern 51 includes the pair of electrode bases 122, the second comb electrodes 122 a and 122 b, and the first to fourth islands 133 of the second outer frame portion 132 shown in FIG. , 134, 135, 136 and the fourth comb electrodes 132a, 132b are patterned corresponding to the planar view form. Further, a photoresist is formed on the first silicon layer 11 by spin coating, and a resist pattern 52 is formed through exposure and development. For example, AZP4210 (manufactured by Clariant Japan) or AZ1500 (manufactured by Clariant Japan) can be used as the photoresist. These can also be used for subsequent photoresists. The resist pattern 52 is used to mask the formation region of the mirror formation portion M, the formation location of the torsion bar T, the formation region of the comb-tooth electrode E1, and the formation region of the frame in the first silicon layer 11.

Next, as shown in FIG. 3C, the first silicon layer 11 is etched to reach the insulating layer 160 by DRIE (Deep Reactive Ion Etching) using the resist pattern 52 as a mask. In DRIE, in the Bosch process in which etching and sidewall protection are alternately performed, etching with SF ₆ gas is performed for 8 seconds, sidewall protection with C ₄ F ₈ gas is performed for 6.5 seconds, and the bias applied to the wafer is 23 W. Therefore, a good etching process can be performed. This condition can also be adopted for the subsequent DRIE on the silicon layer and the polysilicon layer. However, wet etching using a KOH solution or the like may be employed instead of DRIE. Further, inductively coupled plasma etching that performs etching in high-density plasma may be employed. By etching the first silicon layer 11 as described above, a pre-torsion bar T ′ that becomes the torsion bar T later is formed. The pre-torsion bar T ′ is in contact with the insulating layer 160 and has a thickness of 5 μm. After the formation of the pre-torsion bar T ′, the resist pattern 52 is peeled off. As the remover, AZ remover 200 (Clariant Japan) can be used. This can also be used for subsequent peeling of the resist pattern.

  Next, the third silicon layer 13 is bonded to the surface of the first SOI wafer 1 on which the pre-torsion bar T ′ is formed, as shown in FIG. At this time, the first SOI wafer 1 and the third silicon layer 13 are preferably heated to 1100 ° C. The third silicon layer 13 is made of silicon imparted with conductivity by doping impurities and has a thickness of 100 μm. However, instead of this, for example, a silicon wafer having a thickness of 300 μm is bonded to the surface on which the pre-torsion bar T ′ of the first SOI wafer 1 is formed, and then the silicon wafer is polished to obtain a third silicon layer having a thickness of 100 μm. It may be 13. As a result, the second SOI wafer 2 incorporating the pre-torsion bar T ′ is produced.

  Next, an oxide film is grown on the third silicon layer 13 by a thermal oxidation method and patterned to form an oxide film pattern 53 as shown in FIG. The oxide film pattern 53 is for masking a portion to be processed into the mirror forming portion M, the comb-tooth electrode E1, and the frame in the third silicon layer 13. More specifically, the oxide film pattern 53 includes the mirror forming part 110, the first comb electrodes 110a and 110b, the inner frame main part 121, the third comb electrodes 121a and 121b, which are shown in FIG. The first outer frame portion 131 is patterned to correspond to the plan view form.

  Next, a photoresist is formed on the second silicon layer 12, and after exposure and development, a resist pattern 54 is formed as shown in FIG. 4B. The resist pattern 54 is for masking areas other than the area corresponding to the mirror forming portion M in the second silicon layer 12. 4B, the resist pattern 54 is not in contact with the second silicon layer 12, but actually, the resist pattern 54 covers the oxide film pattern 51 and the second silicon layer. Intimately formed on layer 12. The same applies to the depiction of the silicon layer and the resist pattern formed thereon in the subsequent drawings.

Next, as shown in FIG. 4C, the second silicon layer 12 is etched by DRIE until the insulating layer 160 is reached using the resist pattern 54 as a mask. At this time, the insulating layer 160 is hardly etched by DRIE using SF ₆ gas and C ₄ F ₈ gas.

  Next, as shown in FIG. 4D, the insulating layer 160 exposed by DRIE in the previous step is removed by etching. At this time, as an etchant for the insulating layer 160 made of silicon oxide, for example, buffered hydrofluoric acid containing hydrofluoric acid and ammonium fluoride can be used. This can also be used for the subsequent etching of the insulating layer 160.

  Next, as shown in FIG. 4E, the first silicon layer 11 from which the insulating layer 160 has been removed and the third silicon layer 13 continuous thereto are subjected to DRIE etching to form a mirror. A part of the part M is formed thin. Thus, in the present embodiment, the thickness of a part of the mirror forming portion M can also be controlled. By making a part of the mirror forming portion M thinner, it is possible to reduce the weight of the mirror forming portion M. As a result, the operation speed of the mirror forming portion 110 is improved in the finished micromirror element 100, and the optical switching device is realized. When used, the switching speed is improved.

  Next, after peeling off the resist pattern 54, as shown in FIG. 5A, a photoresist 55 'is formed by spraying from above in the drawing. As the photoresist solution to be sprayed, for example, AZP4210 (manufactured by Clariant Japan) diluted 5 times with AZ5200 thinner (manufactured by Clariant Japan) can be used. This can also be used for subsequent photoresist sprays.

  Next, a resist pattern 55 is formed through exposure and development on the photoresist 55 'as shown in FIG. That is, the photoresist 55 ′ is stripped from the second silicon layer 12. The resist pattern 55 is for masking the back surface of the mirror forming portion M in the third silicon layer 13.

  Next, as shown in FIG. 5C, the second silicon layer 12 is etched by DRIE until the insulating layer 160 is reached using the oxide film pattern 51 as a mask. Thereby, the comb electrode E2 is formed. At this time, the mirror forming portion M is not etched because it is masked by the resist pattern 55. Thereafter, as shown in FIG. 5D, the resist pattern 55 is removed from the back surface of the mirror forming portion M.

  Next, as shown in FIG. 6 (a), a photoresist 56 'is formed on the third silicon layer 13 by spin coating, and after exposure and development, a resist pattern is obtained as shown in FIG. 6 (b). 56 is formed. The resist pattern 56 is for masking the formation region of the mirror formation portion M, the formation region of the comb-tooth electrode E1, and the formation region of the frame in the third silicon layer 13 and the first silicon layer 11 continuous thereto. .

  Next, as shown in FIG. 6C, the pre-torsion bar T ′ is exposed by DRIE with respect to the third silicon layer 13 and the first silicon layer 11 continuous thereto, using the resist pattern 56 as a mask. Etching is performed until Thereafter, as shown in FIG. 6D, the resist pattern 56 is peeled off.

  Next, as shown in FIG. 7A, a photoresist 57 ′ is formed by spraying from below in the drawing, and after exposure and development, a resist pattern 57 as shown in FIG. 7B is formed. To do. The resist pattern 57 is for masking the pre-torsion bar T ′.

  Next, as shown in FIG. 7C, the third silicon layer 13 and the first silicon layer 11 continuous thereto are etched to the insulating layer 160 by DRIE using the oxide film pattern 53 as a mask. Process. Thereby, the comb electrode E1 is formed. At this time, the pre-torsion bar T ′ masked by the resist pattern 57 is not etched.

  Next, after removing the resist pattern 57, the exposed insulating layer 160 is removed by etching, as shown in FIG. At this time, the silicon oxide or oxide film patterns 51 and 53 exposed on the element surface are also removed. Thus, a pair of upper and lower comb electrodes E1 and E2 having a thickness of 100 μm are formed. Further, a thin torsion bar T having a thickness of 5 μm with high accuracy is formed in the middle of the second SOI wafer 2 accurately. Furthermore, a mirror forming portion M having a thin portion is formed. As a result, the micromirror 100 that can be driven with low power is obtained.

  8 to 12 show a series of steps in the micromirror element manufacturing method according to the third embodiment of the present invention. This method is also a method for forming the above-described micromirror element 100 by micromachining technology. 8 to 12, as in FIGS. 3 to 7, mainly the formation process of the mirror forming portion M, the torsion bar T, and the pair of comb-tooth electrodes E <b> 1 and E <b> 2 by one modeled cross section. Represents.

  In the present embodiment, first, the second embodiment is shown in FIG. 8A with respect to the first SOI wafer 1 through the same steps as described with reference to FIGS. 3A to 3C. Process to the state. Specifically, in the first SOI wafer 1 shown in FIG. 8A, an oxide film pattern 51 is formed on the second silicon layer 12, and the first SOI wafer 1 is subjected to the first by DRIE using the resist pattern 52 as a mask. In the silicon layer 11, a pre-torsion bar T ′ having a thickness of 5 μm is formed.

  Next, the resist pattern 52 is peeled off, an oxide film is grown on the first silicon layer 11 by thermal oxidation, and this is patterned to form an oxide film pattern 58 as shown in FIG. 8B. To do. The oxide film pattern 58 is for masking the pre-torsion bar T ′ in a later etching process.

  On the other hand, in the present embodiment, a silicon wafer 13 ′ to be bonded to the first SOI wafer 1 and serving as the third silicon layer 13 is prepared, a photoresist is formed on the silicon wafer 13 ′, and exposure and development are performed. As shown in FIG. 8C, a resist pattern 59 is formed. The silicon wafer 13 ′ is made of silicon imparted with conductivity by doping with impurities and has a thickness of 100 μm. The resist pattern 59 is for masking the formation area of the mirror formation portion M, the formation area of the comb-tooth electrode E1, and the formation area of the frame in the silicon wafer 13 '.

  Next, as shown in FIG. 8D, the trench 13a is formed by etching the silicon wafer 13 'to a predetermined depth by DRIE using the resist pattern 59 as a mask. Thereafter, the resist pattern 59 is peeled off.

  Then, as shown in FIG. 8E, the silicon wafer 13 ′ is bonded to the first silicon layer 11 of the first SOI wafer 1 while being heated to 1100 ° C. in a vacuum. At this time, the two wafers are aligned so that the pre-torsion bar T 'faces the groove 13a of the silicon wafer 13'. In this way, the second SOI wafer 2 with the third silicon layer 13 is produced while incorporating the pre-torsion bar T ′.

  Next, an oxide film is grown on the third silicon layer 13 by a thermal oxidation method and patterned to form an oxide film pattern 53 similar to that of the first embodiment as shown in FIG. To do. Specifically, the oxide film pattern 53 includes the mirror forming portion 110, the first comb electrodes 110a and 110b, the inner frame main portion 121, the third comb electrodes 121a and 121b, which are shown in FIG. The first outer frame portion 131 is patterned so as to correspond to the planar view form.

  Next, a photoresist is formed on the second silicon layer 12, and after exposure and development, a resist pattern 54 is formed as shown in FIG. 9B. The resist pattern 54 is for masking a region other than the region corresponding to the mirror forming portion M in the second silicon layer 12. Next, as shown in FIG. 9C, the second silicon layer 12 is etched by DRIE until the insulating layer 160 is reached using the resist pattern 54 as a mask. Next, as shown in FIG. 9D, the insulating layer 160 exposed by DRIE in the previous step is removed by etching. Next, as shown in FIG. 9 (e), the first silicon layer 11 from which the insulating layer 160 has been removed and the third silicon layer 13 continuous thereto are subjected to an etching process by DRIE, thereby forming a mirror. Part of the part M is formed into a thin wall. The process shown in FIG. 9 of the present embodiment is substantially the same as the process described in the second embodiment with reference to FIG.

  Next, after the resist pattern 54 is peeled off, as shown in FIG. 10A, a photoresist 55 ′ is formed by spraying from above in the drawing, and after exposure and development, FIG. 10B is obtained. A resist pattern 55 as shown is formed. The resist pattern 55 is for masking the back surface of the mirror forming portion M in the third silicon layer 13. Next, as shown in FIG. 10C, the first silicon layer 11 is etched by DRIE until the insulating layer 160 is reached using the oxide film pattern 51 as a mask. Thereby, the comb electrode E2 is formed. Thereafter, as shown in FIG. 10D, the resist pattern 55 is removed. The process shown in FIG. 10 of the present embodiment is substantially the same as the process described in the second embodiment with reference to FIG.

  Next, as shown in FIG. 11A, a photoresist 56 ′ is formed on the third silicon layer 13, and after exposure and development, a resist pattern 56 is formed as shown in FIG. 11B. To do. The resist pattern 56 is for masking the formation region of the mirror formation portion M, the formation region of the comb-tooth electrode E1, and the formation region of the frame in the third silicon layer 13 and the first silicon layer 11 continuous thereto. . Next, as shown in FIG. 11C, the pre-torsion bar T ′ is exposed by DRIE with respect to the third silicon layer 13 and the first silicon layer 11 continuous thereto, using the resist pattern 56 as a mask. Etching is performed until At this time, since the oxide film pattern 58 is formed on the pre-torsion bar T ', it is possible to appropriately prevent the pre-torsion bar T' from being etched. Thereafter, as shown in FIG. 11D, the resist pattern 56 is peeled off. The process shown in FIG. 11 of this embodiment is substantially the same as the process described in the second embodiment with reference to FIG.

  Next, as shown in FIG. 12A, a photoresist 57 ′ is formed by spraying from below in the drawing, and after exposure and development, a resist pattern 57 as shown in FIG. 12B is formed. to. The resist pattern 57 is for further masking the pre-torsion bar T ′. Next, as shown in FIG. 12C, the third silicon layer 13 and the first silicon layer 11 continuous thereto are etched to the insulating layer 160 by DRIE using the oxide film pattern 53 as a mask. processing is carried out. Thereby, the comb electrode E1 is formed. At this time, since the pre-torsion bar T ′ is further masked by the resist pattern 57 in addition to the oxide film pattern 58, the pre-torsion bar T ′ is satisfactorily prevented from being eroded. Next, as shown in FIG. 12D, after the resist pattern 57 is removed, the exposed insulating layer 160 and oxide film pattern 58 are removed by etching. At this time, the silicon oxide or oxide film patterns 51 and 53 exposed on the element surface are also removed. Thus, a pair of upper and lower comb electrodes E1 and E2 having a thickness of 100 μm are formed. Further, a thin torsion bar T having a thickness of 5 μm with high accuracy is formed in the middle of the second SOI wafer 2 accurately. Furthermore, a mirror forming portion M having a thin portion is formed. As a result, the micromirror 100 that can be driven with low power is obtained. Note that the process shown in FIG. 12 of the present embodiment is substantially the same as the process described in the second embodiment with reference to FIG.

  13 to 17 show a series of steps in the micromirror element manufacturing method according to the fourth embodiment of the present invention. This method is also a method for forming the above-described micromirror element 100 by micromachining technology. In FIGS. 13 to 17, as in FIGS. 3 to 7, the formation process of the mirror forming portion M, the torsion bar T, and the pair of comb electrodes E <b> 1 and E <b> 2 is mainly performed by one modeled cross section. Represents.

  In the present embodiment, first, as shown in FIG. 13A, the same first SOI wafer 1 as shown in FIG. 3A in the second embodiment is prepared. Next, as shown in FIG. 13B, as shown in FIG. 3B in the second embodiment, an oxide film made of silicon oxide is formed on the second silicon layer 12 by a thermal oxidation method. The oxide film pattern 51 is formed by patterning this. In this step, an oxide film 58 'is grown also on the first silicon layer, but the oxide film 58' is not patterned.

  Next, a photoresist is formed on the oxide film 58 'and patterned to form a resist pattern 60 as shown in FIG. Next, the oxide film 58 ′ is etched using the resist pattern 60 as a mask, and then the resist pattern 60 is peeled off to form an oxide film pattern 58 as shown in FIG. The oxide film pattern 58 is for masking the pre-torsion bar T ′ in a later etching process.

  Next, a silicon wafer 13 ′ similar to that described with reference to FIGS. 8C and 8D with respect to the third embodiment is prepared, and the silicon wafer 13 ′ after the resist pattern 59 is peeled off is prepared. As shown in FIG. 13E, bonding is performed to the first SOI wafer 1 of the present embodiment. At this time, both wafers are aligned so that the oxide film pattern 58 for masking the pre-torsion bar T ′ in the subsequent process faces the groove 13 a of the silicon wafer 13 ′.

  Next, an oxide film is grown on the third silicon layer 13 by a thermal oxidation method and patterned to form an oxide film pattern 53 similar to that of the first embodiment as shown in FIG. To do.

  Next, a photoresist is formed on the second silicon layer 12, and after exposure and development, a resist pattern 54 is formed as shown in FIG. 14B. The resist pattern 54 is for masking a region other than the region corresponding to the mirror forming portion M in the second silicon layer 12. Next, as shown in FIG. 14C, the second silicon layer 12 is etched by DRIE until the insulating layer 160 is reached using the resist pattern 54 as a mask. Next, as shown in FIG. 14D, the insulating layer 160 exposed by DRIE in the previous step is removed by etching. Next, as shown in FIG. 14E, the first silicon layer 11 from which the insulating layer 160 has been removed and the third silicon layer 13 continuous thereto are subjected to an etching process by DRIE, thereby forming a mirror. Part of the part M is formed into a thin wall. The process shown in FIG. 14 of the present embodiment is substantially the same as the process described in the second embodiment with reference to FIG.

  Next, after the resist pattern 54 is peeled off, as shown in FIG. 15A, a photoresist 55 ′ is formed by spraying from above in the drawing, and after exposure and development, FIG. 15B is obtained. A resist pattern 55 as shown is formed. The resist pattern 55 is for masking the back surface of the mirror forming portion M in the third silicon layer 13. Next, as shown in FIG. 15C, the first silicon layer 11 is etched by DRIE until reaching the insulating layer 160 using the oxide film pattern 51 as a mask. Thereby, the comb electrode E2 is formed. Thereafter, as shown in FIG. 15D, the resist pattern 55 is removed. The process shown in FIG. 15 of the present embodiment is substantially the same as the process described in the second embodiment with reference to FIG.

  Next, as shown in FIG. 16A, a photoresist 56 ′ is formed on the third silicon layer 13, and after exposure and development, a resist pattern 56 is formed as shown in FIG. 16B. To do. The resist pattern 56 is for masking the formation region of the mirror formation portion M, the formation region of the comb-tooth electrode E1, and the formation region of the frame in the third silicon layer 13 and the first silicon layer 11 continuous thereto. . Next, as shown in FIG. 16C, the oxide film 58 is exposed by DRIE with respect to the third silicon layer 13 and the first silicon layer 11 continuous therewith, using the resist pattern 56 as a mask. Etching is performed until the insulating layer 160 is reached. As a result, a pre-torsion bar T ′ in contact with the insulating layer 160 is formed. At this time, since the oxide film pattern 58 is formed on the pre-torsion bar T ', it is possible to appropriately prevent the pre-torsion bar T' from being etched inappropriately. Thereafter, as shown in FIG. 16D, the resist pattern 56 is peeled off. The process shown in FIG. 16 of the present embodiment is substantially the same as the process described in the second embodiment with reference to FIG.

  Next, as shown in FIG. 17A, a photoresist 57 ′ is formed by spraying from below in the drawing, and after exposure and development, a resist pattern 57 as shown in FIG. 17B is formed. To do. The resist pattern 57 is for further masking the pre-torsion bar T ′. Next, as shown in FIG. 17C, the third silicon layer 13 and the first silicon layer 11 continuous therewith are etched to the insulating layer 160 by DRIE using the oxide film pattern 53 as a mask. Process. Thereby, the comb electrode E1 is formed. At this time, since the pre-torsion bar T ′ is further masked by the resist pattern 57 in addition to the oxide film pattern 58, the pre-torsion bar T ′ is satisfactorily prevented from being eroded. Next, as shown in FIG. 17D, after the resist pattern 57 is removed, the exposed insulating layer 160 and oxide film pattern 58 are removed by etching. At this time, the silicon oxide or oxide film patterns 51 and 53 exposed on the element surface are also removed. Thus, a pair of upper and lower comb electrodes E1 and E2 having a thickness of 100 μm are formed. Further, a thin torsion bar T having a thickness of 5 μm with high accuracy is formed in the middle of the second SOI wafer 2 accurately. Furthermore, a mirror forming portion M having a thin portion is formed. As a result, the micromirror 100 that can be driven with low power is obtained. Note that the process shown in FIG. 17 of the present embodiment is substantially the same as the process described in the second embodiment with reference to FIG.

  18 and 19 show a series of steps in the micromirror element manufacturing method according to the fifth embodiment of the present invention. This method is also a method for forming the above-described micromirror element 100 by micromachining technology. 18 and 19, the formation process of the torsion bar T is mainly represented by one modeled cross section.

  In this embodiment, first, as shown in FIG. 18A, a mask pattern 61 is formed on the SOI wafer 3 using an oxide film or a photoresist. The SOI wafer 3 has a laminated structure including a first silicon layer 14, a second silicon layer 15, and an insulating layer 160 as an intermediate layer sandwiched therebetween. The first silicon layer 14 and the second silicon layer 15 are made of silicon imparted with conductivity by doping an n-type impurity such as P or As. The insulating layer 160 is made of silicon oxide grown on the surface of the first silicon layer 14 or the second silicon layer 15 by a thermal oxidation method. In the present embodiment, the thickness of the first silicon layer 14 is 100 μm, the thickness of the second silicon layer 15 is 100 μm, and the thickness of the insulating layer 160 is 1 μm.

  Next, as shown in FIG. 18B, the groove portion 14a is formed by performing etching on the first silicon layer 14 using the mask pattern 61 as a mask until it reaches the insulating layer 160 by DRIE. . Thereafter, the mask pattern 61 is removed. Next, as shown in FIG. 18C, polysilicon layers 14 ′ and 15 ′ are formed over the entire surface of the SOI wafer 3. As a film forming technique, low pressure CVD can be employed. Low pressure CVD can also be employed in the subsequent formation of the polysilicon layer. In the present embodiment, the polysilicon layers 14 ′ and 15 ′ have a thickness of 5 μm. The polysilicon used at this time is previously given conductivity by doping impurities. Next, an oxide film is grown on the polysilicon layer 15 ′ on the second silicon layer 15 side by thermal oxidation, and this is patterned to form an oxide film pattern 62 as shown in FIG. .

  Next, as shown in FIG. 19A, the second silicon layer 15 and the polysilicon layer 15 ′ laminated thereon are etched to the insulating layer 160 by DRIE using the oxide film pattern 62 as a mask. Process. Next, as shown in FIG. 19B, the insulating layer 160 exposed by DRIE in the previous step is removed by etching. Next, as shown in FIG. 19C, the polysilicon layer 14 'exposed to the second silicon layer 15 side in the previous step is etched away from the second silicon layer 15 side by DRIE. As a result, a pre-torsion bar T ′ in contact with the insulating layer 160 is formed. Next, as shown in FIG. 19D, the insulating layer 160 in contact with the pre-torsion bar T ′ is removed by etching. Specifically, by dipping the SOI wafer 3 in an etching solution, the insulating layer 160 is dissolved, and the second silicon layer 15 and the like that have been bonded to the insulating layer 160 in contact with the pre-torsion bar T ′ are removed. At this time, the silicon oxide or oxide film pattern 62 exposed on the element surface is also removed at the same time. As a result, a torsion bar T is formed.

  Thus, also in the present embodiment, first, the pre-torsion bar T ′ in contact with the insulating layer 160 is formed, and the insulating layer 160 in contact with the pre-torsion bar T ′ is removed in the subsequent process, so that the torsion bar T is formed. The thickness of the pre-torsion bar T ′ can be determined by the thickness of the polysilicon layer 14 ′ formed in the step shown in FIG. Therefore, in the present embodiment, a thin torsion bar T having a thickness of 5 μm with high precision is formed by a film forming technique while being accurately disposed in the middle of the SOI wafer 3. As a result, the micromirror 100 that can be driven with low power is obtained.

  20 and 21 show a series of steps in the micromirror element manufacturing method according to the sixth embodiment of the present invention. This method is also a method for forming the above-described micromirror element 100 by micromachining technology. 20 and FIG. 21, as in FIGS. 18 and 19, the formation process of the torsion bar T is mainly represented by one modeled cross section.

  In the present embodiment, first, the state shown in FIG. 20A with respect to the SOI wafer 3 is performed through the same steps as those described with reference to FIGS. 18A to 18C in the fifth embodiment. To process. Specifically, the SOI wafer 3 illustrated in FIG. 20A has a stacked structure including a first silicon layer 14, a second silicon layer 15, and an insulating layer 160 therebetween, and the first silicon layer 14, a groove portion 14a is formed. Polysilicon layers 14 ′ and 15 ′ are formed over the entire surface of the SOI wafer 3.

  In the present embodiment, next, as shown in FIG. 20B, a photoresist 63 ′ is formed on the polysilicon layer 14 ′, and this is patterned, as shown in FIG. 20C. Then, a resist pattern 63 is formed. The resist pattern 63 is for masking a portion to be processed into the torsion bar T in the polysilicon layer 14 ′. Next, as shown in FIG. 20D, the polysilicon layer 14 'exposed in the step of FIG. 20C is etched away by DRIE using the resist pattern 63 as a mask. Thereby, the pre-torsion bar T ′ in contact with the insulating layer 160 is formed.

  Next, as shown in FIG. 21A, the resist pattern 63 is removed. Next, a resist is formed on the polysilicon layer 15 ′ and patterned to form a resist pattern 64 as shown in FIG. Next, the second silicon layer 15 and the polysilicon layer 15 ′ stacked thereon are subjected to an etching process up to the insulating layer 160 by DRIE using the resist pattern 64 as a mask. Next, as shown in FIG. 21 (d), the torsion bar T is completed by etching away the insulating layer 160 with which the pre-torsion bar T 'is in contact. Thereafter, the resist pattern 64 is removed as necessary.

  Thus, also in the present embodiment, first, the pre-torsion bar T ′ in contact with the insulating layer 160 is formed, and the insulating layer 160 in contact with the pre-torsion bar T ′ is removed in the subsequent process, so that the torsion bar T is formed. The thickness of the pre-torsion bar T ′ can be determined by the thickness of the polysilicon layer 14 ′ formed in the step shown in FIG. Therefore, in the present embodiment, a thin torsion bar T having a thickness of 5 μm with high precision is formed by a film forming technique while being accurately disposed in the middle of the SOI wafer 3. As a result, the micromirror 100 that can be driven with low power is obtained.

  22 and 23 show a series of steps in the micromirror element manufacturing method according to the seventh embodiment of the present invention. This method is also a method for forming the above-described micromirror element 100 by micromachining technology. In FIGS. 22 and 23, as in FIGS. 18 and 19, the formation process of the torsion bar T is mainly represented by one modeled cross section.

  In the present embodiment, first, as shown in FIG. 22A, a predetermined groove 16a is formed, and an oxide film 65 ′ is formed on the surface of the silicon wafer 4 to be the first silicon layer 16 on the groove 16a side. Further, a polysilicon layer 16 ′ is laminated on the oxide film 65 ′ so as to close the groove 16a. Next, as shown in FIG. 22B, the oxide film 65 'and the polysilicon layer 16' are removed by polishing, leaving a portion filled in the groove 16a. Next, as shown in FIG. 22C, oxide films 66 'and 67' are grown over the entire surface of the silicon wafer 4 by thermal oxidation. The oxide film 66 'later becomes the insulating layer 160 as an intermediate layer in the material substrate. Therefore, in this step, a pre-torsion bar T ′ made of polysilicon 16 ′ in contact with the insulating layer 160 is formed. Next, as shown in FIG. 22 (d), the second silicon layer 17 is bonded to the groove 16 a side of the silicon wafer 4. As a result, the SOI wafer 5 having a stacked structure of the first silicon layer 16, the second silicon layer 17, and the oxide film 66 ', that is, the insulating layer 160 therebetween, is formed. Next, an oxide film pattern 67 is formed as shown in FIG. 22E by patterning the oxide film 67 'exposed on the surface on the first silicon layer 16 side.

  Next, as shown in FIG. 23A, with the oxide film pattern 67 as a mask, the first silicon layer 16 is etched by DRIE until the oxide film 65 ′ formed in the groove 16a is exposed. I do. Next, an oxide film is grown on the second silicon layer 17 and patterned to form an oxide film pattern 68 as shown in FIG. Next, as shown in FIG. 23C, using the oxide film pattern 68 as a mask, the second silicon layer 17 is etched by DRIE until the insulating layer 160 is reached. Next, as shown in FIG. 23D, the insulating layer 160 and the oxide film 65 'exposed in the step of FIG. 23C are removed by being immersed in an etching solution. At this time, the silicon oxide or oxide film patterns 67 and 68 exposed on the element surface are also removed. Thereby, the torsion bar T is formed.

  Thus, also in the present embodiment, first, the pre-torsion bar T ′ in contact with the insulating layer 160 is formed, and the insulating layer 160 in contact with the pre-torsion bar T ′ is removed in the subsequent process, so that the torsion bar T is formed. The thickness of the pre-torsion bar T ′ can be determined by the thickness of the polysilicon layer 16 ′ formed and polished in the steps shown in FIGS. Therefore, in the present embodiment, a thin torsion bar T having a thickness of 5 μm with high accuracy is formed while being accurately arranged in the middle of the SOI wafer 5. As a result, the micromirror 100 that can be driven with low power is obtained.

  24 and 25 show a series of steps in the micromirror element manufacturing method according to the eighth embodiment of the present invention. This method is also a method for forming the above-described micromirror element 100 by micromachining technology. 24 and 25, the formation process of the torsion bar T is mainly represented by one modeled cross section, as in FIGS.

  In the present embodiment, first, as shown in FIG. 24A, an etching process is performed to a depth corresponding to the thickness of the torsion bar T through a mask pattern that masks a portion to be processed into the torsion bar T. A silicon wafer 6 to be the first silicon layer 18 is prepared later. Next, as shown in FIG. 24B, the second silicon layer 19 on which the oxide film 69 ′ is formed is bonded to the etched surface of the silicon wafer 6. Thus, the SOI wafer 7 is formed, and the oxide film 69 ′ becomes an insulating layer 160 as an intermediate layer in the SOI wafer 7. Next, as shown in FIG. 24C, an oxide film pattern 70 is formed on the second silicon layer 19. Next, as shown in FIG. 24D, the second silicon layer 19 is etched by DRIE until the insulating layer 160 is reached using the oxide film pattern 70 as a mask.

  Next, as shown in FIG. 25A, an oxide film pattern 71 is formed on the first silicon layer 18. Next, as shown in FIG. 25B, the first silicon layer 18 is etched to a predetermined depth by DRIE using the oxide film pattern 71 as a mask. As a result, a pre-torsion bar T ′ in contact with the insulating layer 160 is formed. Next, as shown in FIG. 25C, the insulating layer 160 in contact with the pre-torsion bar T ′ is removed by etching. At this time, the silicon oxide or oxide film patterns 70 and 71 exposed on the element surface are also removed. Thereby, the torsion bar T is formed.

  Thus, also in the present embodiment, first, the pre-torsion bar T ′ in contact with the insulating layer 160 is formed, and the insulating layer 160 in contact with the pre-torsion bar T ′ is removed in the subsequent process, so that the torsion bar T is formed. The thickness of the pre-torsion bar T ′ can be determined by the depth of etching performed in the step shown in FIG. Therefore, in the present embodiment, a thin torsion bar T having a thickness of 5 μm with high accuracy is formed while being accurately arranged in the middle of the SOI wafer 7. As a result, the micromirror 100 that can be driven with low power is obtained.

  26 and 27 show a series of steps in the micromirror element manufacturing method according to the ninth embodiment of the present invention. This method is also a method for forming the above-described micromirror element 100 by micromachining technology. In FIGS. 26 and 27, as in FIGS. 18 and 19, the formation process of the torsion bar T is mainly represented by one modeled cross section.

  In the present embodiment, first, an oxide film pattern 72 is formed on the SOI wafer 8 as shown in FIG. The SOI wafer 8 has a laminated structure including a first silicon layer 20, a second silicon layer 21, and an insulating layer 160 as an intermediate layer sandwiched between them. The first silicon layer 20 and the second silicon layer 21 are made of silicon imparted with conductivity by doping an n-type impurity such as P or As. The insulating layer 160 is made of silicon oxide grown on the surface of the first silicon layer 20 or the second silicon layer 21 by a thermal oxidation method. In the present embodiment, the thickness of the first silicon layer 20 is 100 μm, the thickness of the second silicon layer 21 is 100 μm, and the thickness of the insulating layer 160 is 1 μm.

  Next, as shown in FIG. 26B, a resist pattern 73 is formed on the surface of the first silicon layer 20 where the oxide film pattern 72 is not formed. The resist pattern 73 is for masking a portion to be processed into the torsion bar T. Next, as shown in FIG. 26C, an etching process is performed by DRIE to a depth corresponding to the thickness of the torsion bar T using the oxide film pattern 72 and the resist pattern 73 as a mask. In this embodiment, the depth is 5 μm. Thereafter, as shown in FIG. 26D, the resist pattern 73 is removed. Next, as shown in FIG. 26E, the first silicon layer 20 is etched by DRIE until the insulating layer 160 is reached using the oxide film pattern 72 as a mask. As a result, a pre-torsion bar T ′ in contact with the insulating layer 160 is formed.

  Next, as shown in FIG. 27A, an oxide film pattern 74 is formed on the second silicon layer 21. Next, as shown in FIG. 27B, the second silicon layer 21 is etched to the insulating layer 160 by DRIE using the oxide film pattern 74 as a mask. Next, as shown in FIG. 27C, the insulating layer 160 in contact with the pre-torsion bar T ′ is removed by being immersed in an etching solution. At this time, the silicon oxide or oxide film patterns 72 and 74 exposed on the element surface are also removed. Thereby, the torsion bar T is formed.

  Thus, in the present embodiment, first, the pre-torsion bar T ′ in contact with the insulating layer 160 is formed by a two-stage etching process. In the subsequent process, the insulating layer 160 in contact with the pre-torsion bar T ′ is removed, and the torsion bar T is formed. Therefore, in the present embodiment, a thin torsion bar T having a thickness of 5 μm with high accuracy is formed while being accurately arranged in the middle of the SOI wafer 8. As a result, the micromirror 100 that can be driven with low power is obtained.

  28 and 29 show a series of steps in the case where the comb electrodes E1 and E2 are formed together with the torsion bar T by the etching process in the same step in the ninth embodiment.

  First, as shown in FIG. 28A, an SOI wafer 8 is prepared as a substrate. As described above, the SOI wafer 8 has a laminated structure including the first silicon layer 20, the second silicon layer 21, and the insulating layer 160 as an intermediate layer sandwiched between them. The first silicon layer 20 and the second silicon layer 21 are made of silicon imparted with conductivity by doping an n-type impurity such as P or As. The insulating layer 160 is made of silicon oxide grown on the surface of the first silicon layer 20 or the second silicon layer 21 by a thermal oxidation method.

  Next, an oxide film is grown on the first silicon layer 20 and the second silicon layer 21 by thermal oxidation, and this is patterned to form oxide film patterns 72 and 74 as shown in FIG. To do. The oxide film patterns 72 and 74 are for masking portions of the first silicon layer 20 and the second silicon layer 21 that are processed into the comb electrodes E1 and E2. Next, as shown in FIG. 28C, a resist pattern 73 for masking a portion where the oxide film pattern 72 is not formed on the first silicon layer 20 where the oxide film pattern 72 is formed. Form. Next, as shown in FIG. 28D, etching is performed by DRIE to a depth of 5 μm corresponding to the thickness of the torsion bar T using the oxide film pattern 72 and the resist pattern 73 as a mask.

  Next, as shown in FIG. 29A, the resist pattern 73 is removed. Next, as shown in FIG. 29B, the first silicon layer 20 is etched by DRIE until the insulating layer 160 is reached using the oxide film pattern 72 as a mask. As a result, a pre-torsion bar T ′ in contact with the insulating layer 160 is formed, and a comb electrode E 2 in contact with the insulating layer 160 is formed. Next, as shown in FIG. 29C, the second silicon layer 21 is etched by DRIE until reaching the insulating layer 160 using the oxide film pattern 74 as a mask. Thereby, the comb electrode E1 is formed. Next, as shown in FIG. 29D, the insulating layer 160 in contact with the pre-torsion bar T ′ exposed in the steps of FIGS. 29B and 29C is removed by etching. At this time, the silicon oxide or oxide film patterns 72 and 74 exposed on the element surface are also removed. Thereby, the torsion bar T is formed.

  In the DRIE performed in the step of FIG. 29A, etching is performed at a depth of 5 μm corresponding to the thickness of the torsion bar, so there is almost no difference in etching rate between the comb electrode portion and the torsion bar portion. However, in the DRIE performed in the step of FIG. 29B, since the etching is several tens of μm deep, a difference occurs in the etching rate based on the difference in opening area between the comb electrode portion and the torsion bar portion, The torsion bar portion tends to be etched faster or deeper. Therefore, when it is necessary to consider such a difference in etching rate, the etching performed in the step of FIG. 29A in which there is no difference in the etching rate is slightly less than the desired torsion bar thickness of 5 μm. Etch deeply. By doing so, in the etching process of the step shown in FIG. 29B, when the etching in the comb electrode portion reaches the insulating layer 160, the upper surface of the pre-torsion bar T ′ is further etched in the torsion bar portion. The thickness of the pre-torsion bar T ′ can be set to a desired thickness of 5 μm.

  30 to 33 show a series of steps in the case where the comb electrodes E1 and E2 are formed by an etching process different from the torsion bar T in the ninth embodiment of the present invention.

  First, as shown in FIG. 30A, the same SOI wafer 8 as described with reference to FIG. Then, an oxide film is grown on the first silicon layer 20 and the second silicon layer 21 by a thermal oxidation method and patterned to form oxide film patterns 72 and 74 as shown in FIG. To do. Next, as shown in FIG. 30C, a resist pattern 75 is formed on the first silicon layer 20. The resist pattern 75 is for masking a portion to be processed into the torsion bar T and masking a region for forming the mirror forming portion M, a region for forming the comb electrodes E1 and E2, and a region for forming the frame. Next, as shown in FIG. 30D, etching is performed by DRIE to a depth of 5 μm corresponding to the thickness of the torsion bar T using the resist pattern 75 as a mask. Next, as shown in FIG. 30E, the resist pattern 75 is peeled off.

  Next, as shown in FIG. 31A, a photoresist 76 ′ is formed on the first silicon layer 20. Next, as shown in FIG. 31B, the photoresist 76 ′ is patterned by exposure and development to form a resist pattern 76. The resist pattern 76 is used to mask the formation area of the mirror forming portion M, the formation areas of the comb electrodes E1 and E2, and the formation area of the frame. Next, as shown in FIG. 31C, the first silicon layer 20 is etched by DRIE until reaching the insulating layer 160 using the resist pattern 76 as a mask. As a result, the pre-torsion bar T ′ that is in contact with the insulating layer 160 is formed independently of the other portions. Next, as shown in FIG. 31D, the resist pattern 76 is peeled off. Next, as shown in FIG. 31E, a photoresist 77 'is formed on the first silicon layer 20 and the pre-torsion bar T' by spraying from above in the drawing.

  Next, as shown in FIG. 32A, a resist pattern 77 is formed by patterning a photoresist 77 'by exposure and development. The resist pattern 77 is for masking the pre-torsion bar T ′. Next, as shown in FIG. 32B, the first silicon layer 20 is etched until the insulating layer 160 is reached using the oxide film pattern 72 as a mask. As a result, the comb electrode E2 in contact with the insulating layer 160 is formed. Next, as shown in FIG. 32C, the resist pattern 77 is peeled off, and a photoresist 78 ′ is formed on the second silicon layer 21. Next, as shown in FIG. 32D, the photoresist 78 ′ is patterned to form a resist pattern 78. Next, as shown in FIG. 32E, the second silicon layer 21 is etched by DRIE until the insulating layer 160 is reached using the resist pattern 78 as a mask.

  Next, as shown in FIG. 33A, the resist pattern 78 is removed. Next, as shown in FIG. 33B, a photoresist 79 'is formed by spraying from below in the drawing. Next, as shown in FIG. 33C, the photoresist 79 ′ is patterned to form a resist pattern 79. Next, as shown in FIG. 33D, the second silicon layer 21 is etched by DRIE until the insulating layer 160 is reached using the oxide film pattern 74 as a mask. Thereby, the comb-tooth electrode E1 in contact with the insulating layer 160 is formed. Next, as shown in FIG. 33E, the resist pattern 79 is peeled off. Next, as shown in FIG. 33F, the exposed insulating layer 160 is removed by etching. At this time, the silicon oxide or oxide film patterns 72 and 74 exposed on the element surface are also removed. Thus, the torsion bar T and the comb-tooth electrodes E1 and E2 are completed separately.

  FIG. 34 is a cross-sectional view of the micromirror element 100 ′ according to the tenth embodiment of the present invention. FIGS. It is sectional drawing equivalent to (c). The micromirror element 100 ′ is different from the micromirror element 100 according to the first embodiment in the laminated structure and the configuration of the torsion bar in the cross section.

  Specifically, in FIG. 34, the inner frame 120 includes an inner frame main part 121, an insulating layer 161 as a first intermediate layer, an inner silicon layer 170, and an insulating layer 162 as a second intermediate layer. And the electrode base 122. The outer frame 130 includes a first outer frame portion 131, an insulating layer 161 as a first intermediate layer, an intermediate silicon layer 170, an insulating layer 162 as a second intermediate layer, and a second outer frame portion 132. It has the laminated structure which consists of.

  In the present embodiment, the inner frame 120 and the outer frame 130 are connected by a torsion bar 150 '. The torsion bar 150 ′ is connected to a part of the inner silicon layer 170 of the inner frame 120 that is in contact with the insulating layer 161 and the insulating layer 162 and a part of the inner silicon layer 170 of the outer frame 130 that is in contact with the insulating layer 161 and the insulating layer 162. ing. Other configurations are the same as those of the micromirror element 100 according to the first embodiment, and a top view and a bottom view of the micromirror element 100 ′ are respectively represented by (a) and (b) in FIG. The

  35 and 36 show a series of steps in the micromirror element manufacturing method according to the eleventh embodiment of the present invention. This method is one method for forming the above-described micromirror element 100 'by micromachining technology. In FIGS. 35 and 36, the process of forming the torsion bar T is mainly represented by one modeled cross section, as in FIGS.

  In this embodiment, first, an oxide film pattern 80 is formed on the SOI wafer 9 as shown in FIG. The SOI wafer 9 has a stacked structure including a first silicon layer 22, a first insulating layer 161, a second silicon layer 23, a second insulating layer 162, and a third silicon layer 24. The modeled second silicon layer 23 shown in this figure corresponds to the internal silicon layer 170 shown in FIG. The first silicon layer 22, the second silicon layer 23, and the third silicon layer 24 are made of silicon or polysilicon imparted with conductivity by doping an n-type impurity such as P or As. In the present embodiment, the thickness of the first silicon layer 22 is 100 μm, the thickness of the second silicon layer 23 is 5 μm, and the thickness of the third silicon layer 24 is 100 μm. The thicknesses of the first insulating layer 161 and the second insulating layer 162 are each 1 μm.

  Next, as shown in FIG. 35B, a resist pattern 81 is formed on the surface of the first silicon layer 22 where the oxide film pattern 80 is not formed to mask a portion to be processed into the torsion bar T. Is done. Next, as shown in FIG. 35C, etching is performed by DRIE to a predetermined depth using the oxide film pattern 80 and the resist pattern 81 as a mask. In this embodiment, the depth is 5 μm. Thereafter, as shown in FIG. 35D, the resist pattern 81 is removed. Next, as shown in FIG. 35E, the first silicon layer 22 is etched by DRIE until the first insulating layer 161 is reached using the oxide film pattern 80 as a mask.

  Next, as shown in FIG. 36A, the first insulating layer 161 exposed in the step of FIG. 35E is removed by etching from the first silicon layer 22 side. Then, as shown in FIG. 36B, the exposed second silicon layer 23 is etched to reach the second insulating layer 162 by DRIE using the first insulating layer 161 as a mask. . As a result, a pre-torsion bar T ′ in contact with the first insulating layer 161 and the second insulating layer 162 is formed. At this time, the first silicon layer 22 remaining at a thickness of 5 μm on the first insulating layer 161 masking the portion to be processed into the torsion bar T is also removed by etching. Next, as illustrated in FIG. 36C, an oxide film pattern 82 is formed on the third silicon layer 24. Next, as shown in FIG. 36D, the third silicon layer 24 is etched by DRIE to reach the second insulating layer 162 using the oxide film pattern 82 as a mask. Next, as shown in FIG. 36E, the first insulating layer 161 and the second insulating layer 162 that are in contact with the pre-torsion bar T ′ are removed by being immersed in an etching solution. At this time, silicon oxide or oxide film patterns 80 and 82 exposed on the element surface are also removed. Thereby, the torsion bar T is formed. In the present embodiment, the resist pattern 81 is removed in the step shown in FIG. 35D. However, the resist pattern 81 having a shape corresponding to the pre-torsion bar T ′ is used as it is as a mask, and the pre-torsion bar T 'May be formed.

  Thus, in the present embodiment, first, the pre-torsion bar T ′ in contact with the first insulating layer 161 and the second insulating layer 162 is formed, and the first step in which the pre-torsion bar T ′ is in contact in the subsequent steps. The insulating layer 161 and the second insulating layer 162 are removed, and the torsion bar T is formed. The thickness of the pre-torsion bar T ′ can be determined in advance by the second silicon layer 23 in the SOI wafer 9. Therefore, in the present embodiment, a thin torsion bar T having a thickness of 5 μm with high accuracy is formed while being accurately arranged in the middle of the SOI wafer 9. As a result, the micromirror 100 that can be driven with low power is obtained.

  37 and 38 show a series of steps in the micromirror element manufacturing method according to the twelfth embodiment of the present invention. This method is one method for forming the above-described micromirror element 100 'by micromachining technology. In FIGS. 37 and 38, the formation process of the torsion bar T is mainly represented by one modeled cross section as in FIGS.

  In the present embodiment, first, an oxide film pattern 83 is formed on the SOI wafer 10 as shown in FIG. The SOI wafer 10 has a laminated structure including a first silicon layer 25, a first insulating layer 161, a second silicon layer 26, a second insulating layer 162, and a third silicon layer 27. Grooves 25a are formed in the first silicon layer 25 using the oxide film pattern 83 as a mask. The modeled second silicon layer 26 shown in this figure corresponds to the internal silicon layer 170 shown in FIG. The first silicon layer 25, the second silicon layer 26, and the third silicon layer 27 are made of silicon or polysilicon imparted with conductivity by doping an n-type impurity such as P or As. In the present embodiment, the thickness of the first silicon layer 25 is 100 μm, the thickness of the second silicon layer 26 is 5 μm, and the thickness of the third silicon layer 27 is 100 μm. The thicknesses of the first insulating layer 161 and the second insulating layer 162 are each 1 μm.

  Next, as shown in FIG. 37B, a photoresist 84 'is formed by spraying from above in the drawing. Next, by patterning the photoresist 84 ', a resist pattern 84 is formed as shown in FIG. The resist pattern 84 is for masking a portion to be processed into the torsion bar T. Next, as shown in FIG. 37D, the first insulating layer 161 exposed in the previous process is removed by etching using the resist pattern 84 as a mask.

  Next, as shown in FIG. 38A, the resist pattern 84 is peeled off. Next, as shown in FIG. 38B, the second silicon layer 26 is etched to the second insulating layer 162 by DRIE using the first insulating layer 161 exposed in the previous step as a mask. I do. As a result, a pre-torsion bar T ′ in contact with the first insulating layer 161 and the second insulating layer 162 is formed. In addition, an oxide film pattern 85 is formed on the third silicon layer 27. Next, as shown in FIG. 38C, the third silicon layer 27 is etched by DRIE until the second insulating layer 162 is reached using the oxide film pattern 85 as a mask. Next, as shown in FIG. 38D, the first insulating layer 161 and the second insulating layer 162 that are in contact with the pre-torsion bar T ′ are removed by being immersed in an etching solution. At this time, the silicon oxide or oxide film patterns 83 and 85 exposed on the element surface are also removed. Thereby, the torsion bar T is formed.

  Thus, in the present embodiment, first, the pre-torsion bar T ′ in contact with the first insulating layer 161 and the second insulating layer 162 is formed, and the first step in which the pre-torsion bar T ′ is in contact in the subsequent steps. The insulating layer 161 and the second insulating layer 162 are removed, and the torsion bar T is formed. The thickness of the pre-torsion bar T ′ can be determined in advance by the second silicon layer 26 in the SOI wafer 10. Therefore, in the present embodiment, a thin torsion bar T having a thickness of 5 μm with high accuracy is formed while being accurately arranged in the middle of the SOI wafer 10. As a result, the micromirror 100 that can be driven with low power is obtained.

  As a summary of the above, the configurations of the present invention and variations thereof are listed below as supplementary notes.

(Supplementary Note 1) A method for manufacturing a micromirror device including a mirror forming portion, a frame portion, and a torsion bar in a material substrate having a laminated structure including a plurality of silicon layers and at least one intermediate layer. ,
Etching the silicon layer to form a pre-torsion bar that is thinner than the mirror forming part and in contact with the intermediate layer;
And a step of forming a torsion bar by removing an intermediate layer in contact with the pre-torsion bar.
(Additional remark 2) It is a method for manufacturing a micromirror element provided with a mirror formation part, a frame part, and a torsion bar,
With respect to the first silicon layer in the first material substrate having a laminated structure of a first silicon layer having a thickness corresponding to the torsion bar, a second silicon layer, and an intermediate layer therebetween, the torsion bar Forming a pre-torsion bar in contact with the intermediate layer by performing a first etching process up to the intermediate layer through a first mask pattern having a portion for masking a portion to be processed;
Forming a second material substrate incorporating the pre-torsion bar by bonding a third silicon layer to the first silicon layer;
Performing a second etching process on the second silicon layer through the second mask pattern including a portion corresponding to the pre-torsion bar in a non-mask region to the intermediate layer;
Performing a third etching process on the third silicon layer through a third mask pattern including a portion corresponding to the pre-torsion bar in a non-mask region until the pre-torsion bar is exposed;
Performing a fourth etching process on the intermediate layer exposed by the second etching process to remove the intermediate layer in contact with the pre-torsion bar to form a torsion bar. The manufacturing method of a micromirror element.
(Supplementary Note 3) A step of forming a fourth mask pattern for masking the pre-torsion bar after forming the pre-torsion bar on the first material substrate and before forming the second material substrate. The manufacturing method of the micromirror element of Claim 2 including these.
(Additional remark 4) It is a method for manufacturing a micromirror element provided with a mirror formation part, a frame part, and a torsion bar,
With respect to the first silicon layer in the first material substrate having a laminated structure of a first silicon layer having a thickness corresponding to the torsion bar, a second silicon layer, and an intermediate layer therebetween, the torsion bar Forming a first mask pattern having a portion for masking a portion to be processed;
Bonding a third silicon layer to the first silicon layer;
Performing a first etching process on the second silicon layer through the second mask pattern including a region where the torsion bar is formed in a non-mask region until reaching the intermediate layer;
A second etching process is performed on the third silicon layer through a third mask pattern including a region where the torsion bar is formed in a non-mask region until the first mask pattern and the intermediate layer are exposed. Forming a pre-torsion bar in contact with the intermediate layer,
And performing a third etching process on the intermediate layer exposed by the first etching process to remove the intermediate layer in contact with the pre-torsion bar to form a torsion bar. The manufacturing method of a micromirror element.
(Additional remark 5) It is a method for manufacturing a micromirror element provided with a mirror formation part, a frame part, and a torsion bar,
A region in which the torsion bar is formed is included in a non-mask region with respect to the first silicon layer in the material substrate having a stacked structure of a first silicon layer, a second silicon layer, and an intermediate layer therebetween. Forming a groove in the first silicon layer by performing a first etching process up to the intermediate layer through a mask pattern;
Forming a silicon-based material on the groove;
Performing a second etching process on the second silicon layer through the second mask pattern having a portion for masking a portion where the torsion bar is formed up to the intermediate layer;
Performing a third etching process on the intermediate layer exposed by the second etching process from the second silicon layer side to the silicon-based material formed in the groove;
Forming a pre-torsion bar made of the silicon-based material in contact with the intermediate layer by removing the silicon-based material exposed by the third etching process by a fourth etching process from the second silicon layer side; When,
And a step of forming a torsion bar by removing an intermediate layer in contact with the pre-torsion bar.
(Additional remark 6) It is a method for manufacturing a micromirror element provided with a mirror formation part, a frame part, and a torsion bar,
A region in which the torsion bar is formed is included in a non-mask region with respect to the first silicon layer in the material substrate having a stacked structure of a first silicon layer, a second silicon layer, and an intermediate layer therebetween. Forming a groove in the first silicon layer by performing a first etching process up to the intermediate layer through a mask pattern;
Forming a silicon-based material on the groove;
A second etching process is performed on the silicon-based material formed in the groove portion up to the intermediate layer through a second mask pattern having a portion for masking a portion to be processed into the torsion bar. Forming a pre-torsion bar made of the silicon-based material in contact with the intermediate layer,
Performing a third etching process on the third silicon layer through the third mask pattern including a portion corresponding to the pre-torsion bar in a non-mask region to the intermediate layer;
Performing a fourth etching process on the intermediate layer exposed by the third etching process to remove the intermediate layer in contact with the pre-torsion bar to form a torsion bar. The manufacturing method of a micromirror element.
(Additional remark 7) It is a method for manufacturing a micromirror element provided with a mirror formation part, a frame part, and a torsion bar,
A first material substrate made of a first silicon layer is subjected to a first etching process through a first mask pattern including a region where the torsion bar is formed in a non-mask region, thereby the first material substrate. Forming a groove in
Forming an intermediate layer material on the groove;
Depositing a silicon-based material so as to fill the groove on the intermediate layer material formed;
By creating a second material substrate having a stacked structure of the first material substrate, an intermediate layer covering the groove portion of the first material substrate, and a second silicon layer in contact with the intermediate layer, the second material Forming a pre-torsion bar made of the silicon-based material in contact with the intermediate layer while being incorporated in a substrate;
A second etching process is performed on the first silicon layer until the intermediate layer material formed in the groove is exposed through a second mask pattern including a portion corresponding to the pre-torsion bar in a non-mask region. A process of performing
Performing a third etching process on the second silicon layer through a third mask pattern including a portion corresponding to the pre-torsion bar in a non-mask region until the intermediate layer is exposed;
The intermediate layer material exposed by the second etching process and the intermediate layer material and the intermediate layer in contact with the pre-torsion bar by performing a fourth etching process on the intermediate layer exposed by the third etching process And a step of forming a torsion bar. The method of manufacturing a micromirror element, comprising:
(Additional remark 8) It is a method for manufacturing a micromirror element provided with a mirror formation part, a frame part, and a torsion bar,
With respect to the first material substrate made of the first silicon layer, through the first mask pattern having a portion for masking a portion to be processed into the torsion bar, the first material substrate is formed to a depth corresponding to the thickness of the torsion bar. A step of performing an etching process;
Creating a second material substrate having a laminated structure of the first material substrate, an intermediate layer in contact with the etched surface of the first material substrate, and a second silicon layer in contact with the intermediate layer;
Performing a second etching process on the second silicon layer through the second mask pattern including a portion to be processed into the torsion bar in a non-mask region until reaching the intermediate layer;
A pre-torsion bar in contact with the intermediate layer is formed by performing a third etching process on the first silicon layer through a third mask pattern including a portion to be processed into the torsion bar in a non-mask region. Forming, and
Performing a fourth etching process on the intermediate layer exposed by the second etching process to remove the intermediate layer in contact with the pre-torsion bar to form a torsion bar. The manufacturing method of a micromirror element.
(Additional remark 9) It is a method for manufacturing a micromirror element provided with a mirror formation part, a frame part, and a torsion bar,
A first mask for masking a portion to be processed into the torsion bar with respect to the first silicon layer in the material substrate having a stacked structure of a first silicon layer, a second silicon layer, and an intermediate layer therebetween. Performing a first etching process to a depth corresponding to the thickness of the torsion bar via a mask pattern and a second mask pattern including a portion to be processed into the torsion bar in a non-mask region;
Removing the first mask pattern;
Forming a pre-torsion bar in contact with the intermediate layer by performing a second etching process on the first silicon layer through the second mask pattern until reaching the intermediate layer;
Performing a third etching process on the second silicon layer through the third mask pattern including a portion corresponding to the pre-torsion bar in the non-mask region until reaching the intermediate layer;
Performing a fourth etching process on the intermediate layer exposed by the third etching process to remove the intermediate layer in contact with the pre-torsion bar to form a torsion bar. The manufacturing method of a micromirror element.
(Additional remark 10) It is a method for manufacturing a micromirror element provided with a mirror formation part, a frame part, and a torsion bar,
A first silicon layer, a second silicon layer having a thickness corresponding to the torsion bar, a third silicon layer, a first intermediate layer between the first silicon layer and the second silicon layer, and a second silicon layer and a third silicon layer; A first mask pattern for masking a portion to be processed into the torsion bar with respect to the first silicon layer in the material substrate having a stacked structure of a second intermediate layer between the silicon layers; and the torsion bar Performing a first etching process to a depth corresponding to the thickness of the torsion bar through a second mask pattern including a portion to be processed into a non-mask region;
Removing the first mask pattern;
By performing a second etching process on the first silicon layer through the second mask pattern to reach the first intermediate layer, a third etching is performed on the first silicon layer on the first intermediate layer. Forming a mask pattern;
A third etching process is performed on the first intermediate layer exposed by the second etching process up to the second silicon layer through the third mask pattern, whereby the first interlayer is exposed on the second silicon layer. Forming a fourth mask pattern in the first intermediate layer;
By performing a fourth etching process on the second silicon layer exposed by the third etching process up to the second intermediate layer through the fourth mask pattern, the first intermediate layer and the Forming a pre-torsion bar sandwiched between second intermediate layers;
Performing a fifth etching process on the third silicon layer through the fifth mask pattern including a portion corresponding to the pre-torsion bar in a non-mask region to the second intermediate layer;
By performing a sixth etching process on the second intermediate layer exposed by the fifth etching process and the first intermediate layer on the pre-torsion bar, the first intermediate layer in contact with the pre-torsion bar and the first intermediate layer And a step of forming a torsion bar by removing two intermediate layers.
(Additional remark 11) The manufacturing method of the micromirror element of Additional remark 9 or 10 which forms the comb-tooth electrode part in the said mirror formation part and / or the said frame part by the said 2nd etching process.
(Additional remark 12) The manufacturing method of the micromirror element of Additional remark 9 or 10 which forms the comb-tooth electrode part in the said mirror formation part and / or the said frame part by the etching process different from a said 2nd etching process.
(Additional remark 13) It is a method for manufacturing a micromirror element provided with a mirror formation part, a frame part, and a torsion bar,
A first silicon layer, a second silicon layer having a thickness corresponding to the torsion bar, a third silicon layer, a first intermediate layer between the first silicon layer and the second silicon layer, and a second silicon layer and a third silicon layer; With respect to the first silicon layer in the material substrate having a laminated structure with a second intermediate layer between the silicon layers, the first mask pattern including a region where the torsion bar is formed in a non-mask region via the first mask pattern. Performing a first etching process up to one intermediate layer;
Forming a second mask pattern for masking a portion to be processed into the torsion bar on the first intermediate layer exposed by the first etching process;
Performing a second etching process on the first intermediate layer up to the second silicon layer through the second mask pattern;
Removing the first mask pattern;
A third etching process is performed on the second silicon layer through the first intermediate layer exposed by the removal of the first mask pattern to reach the second intermediate layer, thereby the first intermediate layer. And forming a pre-torsion bar in contact with the second intermediate layer;
Performing a fourth etching process on the third silicon layer through the third mask pattern including a portion corresponding to the pre-torsion bar in the non-mask region to the second intermediate layer;
By performing a fifth etching process on the second intermediate layer exposed by the fourth etching process and the first intermediate layer on the pre-torsion bar, the first intermediate layer in contact with the pre-torsion bar and the first intermediate layer And a step of forming a torsion bar by removing two intermediate layers.
(Additional remark 14) The said etching process with respect to the said silicon layer is a manufacturing method of the micromirror element as described in any one of additional marks 1-13 performed by inductively coupled plasma etching.
(Supplementary note 15) Any one of Supplementary notes 1 to 14, wherein the frame portion includes a first frame and a second frame, and the torsion bar includes a frame torsion bar connecting the first frame and the second frame. The manufacturing method of the micromirror element as described in one.
(Supplementary Note 16) Mirror forming part;
A frame portion having a laminated structure including a plurality of silicon layers and at least one intermediate layer;
It is thinner than the mirror forming portion, and defines a rotation axis for rotating the mirror forming portion with respect to the frame portion, and at least one end is connected to a portion of the silicon layer that contacts the intermediate layer. A micromirror device comprising: a torsion bar.
(Supplementary Note 17) The frame portion includes a first frame and a second frame,
17. The micro of claim 16, wherein the torsion bar is connected to a portion of the first frame in contact with the intermediate layer in the silicon layer and a portion of the second frame in contact with the intermediate layer of the silicon layer. Mirror element.
(Supplementary Note 18) The frame portion has two intermediate layers, and at least one end of the torsion bar is connected to a portion in contact with the two intermediate layers in the silicon layer between the two intermediate layers. 16. The micromirror element according to 16.
(Supplementary Note 19) The frame portion includes a first frame and a second frame,
The torsion bar includes a portion in contact with the two intermediate layers in the silicon layer between the two intermediate layers of the first frame, and the two layers in the silicon layer between the two intermediate layers of the second frame. Item 19. The micromirror element according to appendix 18, which is connected to a portion in contact with the intermediate layer.
(Additional remark 20) The said intermediate | middle layer is a micromirror element as described in any one of additional remark 16 to 19 comprised with the insulating material.
(Additional remark 21) In order that the said mirror formation part has a 1st comb-tooth electrode part, and the said frame part displaces the said mirror formation part by producing an electrostatic force between the said 1st comb-tooth electrode part. 21. The micromirror element according to any one of appendices 16 to 20, having the second comb electrode portion.
(Supplementary Note 22) The first frame includes a third comb electrode portion, and the second frame generates an electrostatic force between the first frame and the mirror. The micromirror element according to any one of appendices 17 and 19 to 21, which has a fourth comb electrode portion for displacing the forming portion.

It is the top view and bottom view of the micromirror element which concerns on the 1st Embodiment of this invention. It is sectional drawing of the micromirror element shown in FIG. It is sectional drawing showing the one part process in the micromirror element manufacturing method which concerns on the 2nd Embodiment of this invention. The process following FIG. 3 is represented. The process following FIG. 4 is represented. The process following FIG. 5 is represented. The process following FIG. 6 is represented. It is sectional drawing showing the one part process in the micromirror element manufacturing method which concerns on the 3rd Embodiment of this invention. The process following FIG. 8 is represented. The process following FIG. 9 is represented. The process following FIG. 10 is represented. The process following FIG. 11 is represented. It is sectional drawing showing the one part process in the micromirror element manufacturing method which concerns on the 4th Embodiment of this invention. The process following FIG. 13 is represented. The process following FIG. 14 is represented. The process following FIG. 15 is represented. The process following FIG. 16 is represented. It is sectional drawing showing the one part process in the micromirror element manufacturing method which concerns on the 5th Embodiment of this invention. The process following FIG. 18 is represented. It is sectional drawing showing the one part process in the micromirror element manufacturing method which concerns on the 6th Embodiment of this invention. The process following FIG. 20 is represented. It is sectional drawing showing a series of processes in the micromirror element manufacturing method which concerns on the 7th Embodiment of this invention. The process following FIG. 22 is represented. It is sectional drawing showing a series of processes in the micromirror element manufacturing method which concerns on the 8th Embodiment of this invention. The process following FIG. 24 is represented. It is sectional drawing showing the one part process in the micromirror element manufacturing method which concerns on the 9th Embodiment of this invention. The process following FIG. 26 is represented. In the micromirror element manufacturing method which concerns on the 9th Embodiment of this invention, it is sectional drawing showing the one part process in the case of forming a comb-tooth electrode with a torsion bar by the etching process of the same process. The process following FIG. 28 is represented. In the micromirror element manufacturing method which concerns on the 9th Embodiment of this invention, it is sectional drawing showing the one part process in the case of forming a comb-tooth electrode by the etching process of a different process from a torsion bar. The process following FIG. 30 is represented. The process following FIG. 31 is represented. The process following FIG. 32 is represented. It is sectional drawing of the micromirror element which concerns on the 10th Embodiment of this invention. It is sectional drawing showing the one part process in the micromirror element manufacturing method which concerns on the 11th Embodiment of this invention. The process following FIG. 35 is represented. It is sectional drawing showing the one part process in the micromirror element manufacturing method which concerns on the 12th Embodiment of this invention. The process following FIG. 37 is represented. It is a schematic block diagram of an example of an optical switching apparatus. It is a schematic block diagram of the other example of an optical switching apparatus. It is a partial omission perspective view of the conventional micromirror element which adopted the flat electrode. In the micromirror element shown in FIG. 41, the state when the inclination angle of the inner frame with respect to the outer frame is θ is shown. It is a partial omission perspective view of the conventional micromirror element which employ | adopted the comb-tooth electrode. It is a fragmentary perspective view showing orientation of a set of comb-tooth electrodes.

Explanation of symbols

100, 100 'Micromirror element 110 Mirror forming part 110a, 110b First comb electrode 120 Inner frame 121 Inner frame main part 121a, 121b Third comb electrode 122 Electrode base 122a, 122b Second comb electrode 130 Outer frame 131 First outer frame part 132 Second outer frame part 132a, 132b Fourth comb electrode 140, 150 Torsion bar 160, 161, 162 Insulating layer 170 Inner silicon layer T Torsion bar T 'Pretorsion bar E1, E2 Comb electrode M mirror forming part

Claims (10)

In a material substrate having a laminated structure including a plurality of silicon layers and at least one intermediate layer, a method for manufacturing a micromirror element including a mirror forming portion, a frame portion, and a torsion bar,
By performing an etching process on the silicon layer, the mirror forming portion is thinner than the mirror forming portion in the silicon layer and is in contact with the intermediate layer, and the mirror forming portion is continuous with the pretorsion bar. And at least a part of the frame portion that is continuous with the pre-torsion bar; and
Forming a torsion bar by removing an intermediate layer in contact with the pre-torsion bar.   The method of manufacturing a micromirror element according to claim 1, wherein the etching process on the silicon layer is performed by inductively coupled plasma etching.   3. The micromirror element according to claim 1, wherein the frame unit includes a first frame and a second frame, and the torsion bar includes a frame torsion bar that connects the first frame and the second frame. Production method. A mirror forming section;
A frame portion having a laminated structure including a plurality of silicon layers and at least one intermediate layer;
It is thinner than the mirror forming portion, and defines a rotation axis for rotating the mirror forming portion with respect to the frame portion, and at least one end is connected to a portion of the silicon layer that contacts the intermediate layer. A torsion bar, and
The micromirror element, wherein the silicon layer and the torsion bar of the frame part are formed from a single silicon lump and are continuous. The frame portion has a first frame and a second frame;
The said torsion bar is connected to the site | part which contact | connects the said intermediate | middle layer in the said silicon | silicone layer of the said 2nd flame | frame, and the site | part which contact | connects the said intermediate | middle layer in the said 2nd flame | frame. Micromirror element.   The said frame part has two intermediate | middle layers, At least one end of the said torsion bar is connected to the site | part which contact | connects the said two intermediate | middle layers in the silicon | silicone layer between the said two intermediate | middle layers. Micromirror element. The frame portion has a first frame and a second frame;
The torsion bar includes a portion in contact with the two intermediate layers in the silicon layer between the two intermediate layers of the first frame, and the two layers in the silicon layer between the two intermediate layers of the second frame. The micromirror element according to claim 6, wherein the micromirror element is connected to a portion in contact with the intermediate layer.   The micromirror element according to claim 4, wherein the intermediate layer is made of an insulating material.   The mirror forming portion has a first comb electrode portion, and the frame portion has a second comb for displacing the mirror forming portion by generating an electrostatic force between the frame portion and the first comb electrode portion. The micromirror element according to any one of claims 4 to 8, which has a tooth electrode portion.   The first frame has a third comb electrode part, and the second frame displaces the first frame and the mirror forming part by generating an electrostatic force between the first frame and the third comb electrode part. The micromirror element according to any one of claims 5 and 7 to 9, further comprising a fourth comb-tooth electrode part for causing the micro-combination.

Images