JP2009198700A - Method for manufacturing mirror of variable shape and mirror of variable shape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently manufacture a mirror of a variable shape without independently manufacturing a substrate for an actuator array and a substrate for a mirror surface. <P>SOLUTION: A method for manufacturing the mirror of the variable shape includes: a step of preparing the actuator array which is constituted by arranging, on a substrate, a plurality of piezoelectric actuators each having a piezo-electric film, a first electrode arranged under the piezo-electric film and a second electrode arranged above the piezo-electric film; a step of forming a sacrificial layer which is finally removed; a step of forming a hole in the sacrificial layer to expose at least a part of the second electrode; a step of filling up the hole formed in the sacrificial layer with a material for a pillar part in order to form the pillar part on the exposed second electrode; a step of flattening top surfaces of the sacrificial layer and the pillar part; a step of forming the mirror surface on the flattened top surfaces of the sacrificial layer and the pillar part; and a step of removing the sacrificial layer by etching after forming the mirror surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a variable shape mirror that changes the shape of a mirror surface and a method of manufacturing the same.

  A mirror surface for reflecting light, a piezoelectric film and an actuator array in which piezoelectric actuators having electrodes arranged above and below the piezoelectric film are two-dimensionally arranged, and the mirror surface and each piezoelectric actuator are arranged between 2. Description of the Related Art A variable shape mirror having a pillar portion (bump) that supports a mirror surface and transmits a displacement of a piezoelectric actuator to the mirror surface is known.

By the way, when manufacturing the variable shape mirror as described above, in the following Non-Patent Document 1, an actuator array substrate and a mirror surface substrate are separately manufactured, and after superposing these, the mirror surface substrate is used. The mirror surface was formed by polishing the substrate by etching.
Yang, E.-H. and 5 others "Thin-Film Piezoelectric Unimorph Actuator-Based Deformable Mirror With a Transferred Silicon Membrane", JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL.15, NO.5, OCTOBER 2006, P1214-P1225

  However, in the case of the above-described method, since the actuator array substrate and the mirror surface substrate are separately manufactured, it takes time to manufacture.

  In view of the above problems, an object of the present invention is to provide a method of manufacturing a deformable mirror that can efficiently manufacture a deformable mirror.

  In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) In the manufacturing method of the variable shape mirror that changes the shape of the mirror surface,
An actuator array is prepared in which a plurality of piezoelectric actuators each having a piezoelectric film, a first electrode disposed under the piezoelectric film, and a second electrode disposed on the piezoelectric film are disposed on a substrate. A preparation process to
A sacrificial layer forming step of forming a sacrificial layer finally removed on the actuator array;
Forming a hole in the sacrificial layer so as to correspond to each of the piezoelectric actuators and exposing at least a part of the second electrode; and
A hole burying step of burying the hole formed in the sacrificial layer with a column portion material to form a column portion that supports the mirror surface on the exposed second electrode;
A planarization step of planarizing the upper surface of the sacrificial layer and the pillar portion;
A mirror surface forming step of forming a mirror surface on the upper surface of the sacrificial layer and the column portion flattened by the flattening step;
A sacrificial layer removing step of removing the sacrificial layer by an etching method after the mirror surface is formed by the mirror surface forming step;
It is characterized by including.
(2) In the manufacturing method of the shape variable mirror of (1),
A recess forming step for forming a recess in the substrate for facilitating displacement of the piezoelectric film between the piezoelectric actuator and a substrate located below the piezoelectric actuator is provided.
(3) In the method for manufacturing a variable shape mirror according to (2), a first passage hole that forms a first passage hole through which dry etching gas passes from the outermost surface to the substrate at each outer edge of the piezoelectric actuator. Forming process;
A second passage hole forming step for forming a second passage hole through which the dry etching gas passes on the mirror surface so as to correspond to each of the piezoelectric actuators,
The sacrificial layer removing step is a step of removing the sacrificial layer by exposing the sacrificial layer to the dry etching gas through the second passage hole,
In the recess forming step, after the sacrificial layer is removed in the sacrificial layer removing step, the upper portion of the substrate is exposed to the dry etching gas through the first passage hole. A predetermined amount is removed, and the recess is formed between the piezoelectric actuator and the substrate.
(4) In the method for manufacturing a deformable mirror according to (3),
In the piezoelectric actuator of the actuator array prepared in the preparation step, γ-alumina is formed between the substrate and the first electrode.
(5) a piezoelectric film, a first electrode formed under the piezoelectric film, and a second electrode formed over the piezoelectric film, wherein the first electrode and the second electrode A piezoelectric element that is displaced by supplying a voltage from an electrode to the piezoelectric film;
A substrate for supporting the piezoelectric element from below;
A recess formed on the lower side of the substrate;
A mirror surface formed above the second electrode or on the bottom surface of the recess;
A suppression layer that suppresses deformation of the mirror surface due to its own weight;
It is characterized by providing.
(6) In the variable shape mirror of (5), the suppression layer is made of any material of SU-8, polyimide, and SIN, and has a thickness of about 10 to 20 μm.
(7) In the deformable mirror of (6),
The mirror surface is disposed on the second electrode;
The suppression layer is disposed between the second electrode and the mirror surface.
(8) In the variable shape mirror of (7),
An elastic member for preventing the deflection of the mirror surface is provided between the mirror surface and the suppression layer.
(9) In the deformable mirror of (5),
The mirror surface is formed on the bottom surface of the recess,
An elastic member for preventing the deflection of the mirror surface is provided between the mirror surface and the bottom surface of the recess.
(10) In the deformable mirror of (5),
Γ-alumina is formed between the substrate and the first electrode.

  According to the present invention, a variable shape mirror can be manufactured efficiently without separately manufacturing a substrate for an actuator array and a substrate for a mirror surface.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a main part of the variable shape mirror according to the present embodiment. The deformable mirror 10 is roughly divided into a piezoelectric actuator array 100 in which a plurality of piezoelectric actuators 101 are arranged, a column part 300 provided on each piezoelectric actuator 101, and a mirror surface 500. As the piezoelectric actuator 101 is displaced when a voltage is applied to the piezoelectric actuator 101, the column portion 300 is displaced up and down, so that the shape of the mirror surface 500 changes.

  FIG. 2 is a cross-sectional view of a main part for explaining the configuration of the piezoelectric actuator array according to the present embodiment. The piezoelectric actuator array 100 has a configuration in which a plurality of piezoelectric actuators 101 are arranged on a substrate 102 as shown in FIG. In the present embodiment, a plurality of piezoelectric actuators 101 are arranged on the substrate 102 in a grid pattern. In this case, the piezoelectric actuators may be configured to be two-dimensionally arranged at a predetermined interval. For example, a configuration in which a plurality of piezoelectric actuators are arranged radially may be used. In the actuator array 100, a plurality of electrode terminals 109 corresponding to each piezoelectric actuator 101 are formed, and a voltage can be supplied to each piezoelectric actuator 101 via each electrode terminal 109.

  In FIG. 2, each piezoelectric actuator 101 includes a piezoelectric film 103, a first electrode 105, and a second electrode 107, and is disposed on the substrate 102. As the piezoelectric film 103, a piezoelectric body that is displaced by applying a voltage is used. The thickness of the piezoelectric film 103 may be about 0.5 to 3 μm, for example. The first electrode 105 is formed on the lower surface of the piezoelectric film 103, and the second electrode 107 is formed on the upper surface of the piezoelectric film 103. That is, the piezoelectric film 103 is sandwiched between the two electrodes of the first electrode 105 and the second electrode 107. Further, the first electrode 105 is electrically connected to the electrode terminal 109 through a wiring (not shown), and when a voltage is applied to the electrode terminal 109, the piezoelectric film 103 is formed on the surface on which the piezoelectric film 103 is formed. Is displaced in a direction perpendicular to In this case, the second electrode 107 and the electrode terminal 109 may be electrically connected. In addition, the 1st electrode 105 and the 2nd electrode 107 consist of metal thin films, such as Ti and Pt, for example.

  The substrate 102 is for supporting the piezoelectric film 103, the first electrode 105, and the second electrode 107 from below, and is formed on the lower surface of the first electrode 105. For example, a silicon substrate (in the case of a 4-inch wafer) having a thickness of about 500 μm can be used as the substrate 102.

Next, a manufacturing method of the variable shape mirror according to the present embodiment will be described with reference to FIGS. First, a process for preparing the actuator array 100 will be described. FIG. 4 is a diagram for explaining a manufacturing process of the piezoelectric actuator array 100. As a material of the substrate 102, the piezoelectric characteristic of the piezoelectric film 103 can be enhanced by using a single crystal material such as Si or MgO, but is not particularly limited. In this embodiment, a single crystal Si substrate having a substrate thickness of about 400 μm is used. Further, γ-Al ₂ O ₃ (alumina: see FIG. 110) is formed on the substrate 102 so that the piezoelectric characteristics of the piezoelectric film 103 are enhanced. There are many methods for forming γ-Al ₂ O ₃ , for example, MBE (Molecular Beam Epitaxy), CVD (Chemical Vapor Deposition), but it is not particularly limited as long as it is a technology capable of forming a film. Absent.

  Next, the first electrode 105 is formed over the substrate 102. As the material of the first electrode 105, a highly conductive metal (for example, Pt, Ti, etc.) is preferably used. Next, the piezoelectric film 103 is formed over the first electrode. As the material of the piezoelectric film 103, a material having a high piezoelectric constant and large deformation such as PZT (lead zirconium titanate) or perovskite containing Pb similar to PZT is preferably used. There are many methods for forming the electrode film and the piezoelectric film, for example, a sputtering method, a CVD method (Chemical Vapor Deposition), or a sol-gel method, but there is no particular limitation as long as it is a technique capable of forming a film. In this embodiment, Pt and Ti are used as the material for the first electrode, and the film thicknesses are 10 nm (Ti) and 100 nm (Pt), respectively. The material of the piezoelectric film 103 is PZT, and the film thickness is about 2 to 3 μm. Pt and Ti are formed by sputtering, and PZT is formed by sol-gel method.

  Next, the second electrode 107 is formed on the piezoelectric film 103. The material and formation method of the second electrode 107 are the same as those of the first electrode 105. In this embodiment, Pt is used as the material, and the film thickness is 100 nm. Pt is formed by sputtering (see FIG. 4A).

  Next, as shown in FIG. 4B, the upper part of the first electrode 105 is exposed around each piezoelectric actuator 101 by using a photolithography method and an etching method in order to form an array of piezoelectric actuators 101. Remove until More specifically, after applying a photoresist on the second electrode 107, an exposure process is performed so as to leave a photosensitive portion using a mask on which an array pattern of the piezoelectric actuators 101 is drawn. Next, the region corresponding to the periphery of each piezoelectric actuator 101 in the second electrode 107 and the piezoelectric film 103 is selectively removed by using a reactive ion etching (RIE) method to expose the second electrode 107. Thereafter, the remaining photoresist is removed by plasma etching, solvent, or the like.

  Next, as shown in FIG. 4C, the first electrode 105 is divided so as to correspond to each piezoelectric actuator 101, and in order to connect each electrode terminal 109, a photolithography method and an etching method are used. In use, the periphery of the first electrode 105 is removed until the γ-alumina 110 is exposed. Note that a specific method can be adopted since the same method as the above-described removal of the second electrode and the piezoelectric film 107 can be adopted, and the description thereof is omitted.

Next, as shown in FIG. 4D, SiO 2 is formed on the entire top surface of the piezoelectric actuator array 100. The method for forming the SiO _2, CVD method, a sputtering method, can be considered like.

  Next, as shown in FIG. 4E, in order to expose the second electrode 107, it is removed by using a photolithography method and an etching method until the upper portion of the second electrode 107 is exposed. Note that a specific method can be adopted since the same method as the above-described removal of the second electrode and the piezoelectric film 107 can be adopted, and the description thereof is omitted.

Next, as shown in FIG. 4 (f), first through holes 120 through which dry etching gas passes are formed on the outer edges of the piezoelectric actuators 101 from the outermost surface to the substrate 102. More specifically, a part of the substrate 102 is removed by removing the SiO ₂ film, the first electrode 105 and the γ-alumina 110 formed around each piezoelectric actuator 101 by using a photolithography method and an etching method. Leave it exposed. In this case, for example, as shown in FIG. 5, when the piezoelectric actuator 101 is viewed from above, the four corners of the piezoelectric actuator 101 are supported so that the piezoelectric actuator 101 is supported by the portions that remain without being removed. On the other hand, it is conceivable that a substantially L-shaped hole 120 (groove) is formed, and the central portion 121 of each side forming the piezoelectric actuator 101 is left. In this case, the piezoelectric actuator 101 is supported at four points by the central portion 121. The hole 120 formed as described above is used as an etching hole through which an etching gas for removing a thin film sacrificial layer 200 and a substrate 102 described later passes.

  FIG. 6 is a diagram for explaining from the step of forming a thin film sacrificial layer on the actuator array 100 to the step of forming a mirror surface. Here, as shown in FIG. 6A, a thin film sacrificial layer 200 to be finally removed is formed on the actuator array 100. In addition, as a material of the thin film sacrificial layer 200, a material having characteristics that are easily removed by a corresponding etching gas is preferable, and polysilicon, amorphous silicon, PSG, BPSG, or the like is used. Moreover, the formation method of the thin film sacrificial layer 200 will not be restrict | limited especially if it is a technique which can form a film | membrane. In the present embodiment, polysilicon is used as the material of the thin film sacrificial layer 200, the film thickness is set to about 10 μm, and the entire upper surface of the actuator array 100 is formed by sputtering or CVD.

  Next, as shown in FIG. 6B, a hole 250 is formed in the thin film sacrificial layer 200 so as to correspond to each of the piezoelectric actuators 101, and at least a part of the second electrode 107 is exposed. In this case, the thin film sacrificial layer 200 is removed using photolithography and an etching method so that the central portion (when viewed from above) of the second electrode 107 in each piezoelectric actuator 101 is exposed.

  Next, as shown in FIG. 6C, in order to form a column portion 300 that supports the mirror surface 500 on the exposed second electrode 107, a hole 250 formed in the sacrificial layer 200 is formed in the column portion. Buried with material. More specifically, a plurality of column portions 300 are formed on the second electrode 107 by pouring metal into the holes 250 formed in the thin film sacrificial layer 200. Moreover, the formation method of the column part 300 will not be restrict | limited especially if it is a technique which can form a column part (for example, electrolytic plating, a vapor deposition method, etc.). In this embodiment, In is used as the material of the column part 300, and the column part 300 is formed by pouring In on the liquid into the hole 250 and then performing a cooling process.

  Next, as shown in FIG. 6D, the upper surfaces of the thin film sacrificial layer 200 and the column part 300 are planarized. In this case, for example, a technique using CMP (Chemical Mechanical Polishing) can be considered. Thereby, the thin film sacrificial layer 200 and the column part 300 which have a flat upper surface are formed. Note that planarization may be performed until the height of the column portion 300 from the second electrode 107 reaches a preset height (for example, about 10 μm).

Next, as shown in FIG. 6E, a reflective mirror surface (mirror film) 500 is formed on the upper surfaces of the flattened thin film sacrificial layer 200 and the column part 300. As a material of the mirror surface 500, for example, a metal such as Au, Ag, Al, or a λ / 4 multilayer film of a low refractive index dielectric / high refractive index dielectric such as SiO ₂ / Ta ₂ O ₅ is preferably used. Is done. Further, there are many methods for forming the mirror surface 500, for example, a sputtering method or a vapor deposition method, but there is no particular limitation as long as it is a technology capable of forming a film. Moreover, as a film thickness of a mirror surface, about 1 micrometer can be considered, for example. In this case, a suppression layer that suppresses deformation of the mirror surface 500 due to the weight of the mirror surface 500 is formed on the upper surfaces of the thin film sacrificial layer 200 and the column part 300, and the mirror surface 500 is formed on the suppression layer. Good. As a material for the suppression layer, SU-8, polyimide, SIN, or the like is preferably used. Moreover, as a formation method of the suppression layer, there are a sputtering method, a CVD method, and the like, but there is no particular limitation as long as it is a technique capable of forming the suppression layer.

  After the mirror surface 500 is formed as described above, next, as shown in FIGS. 7 and 8, the second etching hole 550 through which the dry etching gas passes corresponds to each piezoelectric actuator 101. Formed on the mirror surface 500. In this case, as the holes 550, it is conceivable that minute holes are formed at four points that are equidistant from the column part 300 by photolithography and etching. More specifically, as shown in FIG. 7, when substantially L-shaped holes 120 (grooves) are formed in the four corners of the piezoelectric actuator 101, when the piezoelectric actuator 101 is viewed from above. The four corners of the hole 120 and the formation position of the hole 550 overlap so that four holes 550 are formed.

Next, as shown in FIG. 8, the sacrificial layer 200 is removed by an etching method. More specifically, the thin film sacrificial layer 200 and the substrate 102 are removed through the holes 550 by disposing the actuator array 100 in a gas that reacts with the thin film sacrificial layer 200 and the substrate 102. In this embodiment, since polysilicon is used as the thin film sacrificial layer 200 and a Si substrate is used as the substrate 102, it may be considered to use an etching gas (for example, XeF ₂ ) having a characteristic of etching silicon. It is done. In this case, substances other than the thin film sacrificial layer 200 and the substrate 102 (for example, the mirror surface 500, the column part 300, the SiO 2 film, etc.) remain without being affected by the etching gas. Note that the present invention is not limited to the method in which the thin film sacrificial layer 200 and the substrate 102 are exposed to the reactive gas as described above, and a reactive ion etching method in which the etching gas is ionized and etched by plasma may be used.

  Here, when the etching process is started, as shown in FIG. 8A, the etching gas passing through the hole 550 scrapes the thin film sacrificial layer 200. At this time, the etching gas scrapes the thin film sacrificial layer 200 radially around the hole 550.

  Then, the portion surrounding the column portion 300 of the thin film sacrificial layer 200 is removed by the etching gas traveling toward the column portion 300 (the central portion of the piezoelectric actuator 101), and the piezoelectric actuator 101 (adjacently disposed) When the thin film sacrificial layer 200 formed between the piezoelectric actuators 101 is removed by the etching gas traveling toward the peripheral side of the piezoelectric actuators 101, it is provided on the second electrode 107 of each piezoelectric actuator 101. The mirror surface 500 is supported from below by the column part 300.

  Further, after the thin film sacrificial layer 200 formed between the hole 550 and the hole 120 is removed by the etching gas traveling downward from the hole 550, the etching gas passes through the hole 120 and enters the substrate 102. When the upper portion of the substrate 102 is exposed to the dry etching gas, the substrate 102 is scraped radially around the hole 120, and a predetermined amount of the upper portion of the substrate 102 is removed. Here, as shown in FIG. 7, the hole 120 formed on the substrate 102 is formed so as to surround the piezoelectric actuator 101 from four directions, and the etching gas traveling toward the central portion of the piezoelectric actuator 101 is As shown in FIG. 8B, the lower surface portion of the first electrode 105 in the substrate 102 is removed. Accordingly, a cavity 590 is formed between the second electrode 107 and the substrate 105. Note that the cavity 590 formed in the lower part of the piezoelectric actuator 101 is used as a space when the piezoelectric film 103 is displaced in the vertical direction when a voltage is applied to the piezoelectric film 103. As a result, a recess (cavity 590) is formed in the substrate 102 between the piezoelectric actuator 101 and the substrate 102 positioned below the piezoelectric actuator 101 to facilitate the displacement of the piezoelectric film 103 up and down.

  In this case, the removal rate by the etching gas is substantially constant in each direction, and the hole 550 formed in the mirror surface 500 and the hole 120 formed in the substrate surface are formed at equal intervals from the center position on the horizontal plane of the piezoelectric actuator 101. As a result, the cavity 590 formed on the lower surface of the piezoelectric actuator 101 is uniformly formed on the surface of the substrate 102. Note that, when the sacrificial layer 200 and a part of the upper portion of the substrate 102 are removed by the etching gas as described above, the sacrificial layer 200 is removed and the cavity 590 is formed after the etching gas is introduced by an experiment or the like. It is sufficient to obtain the time in advance.

  If it is set as the above manufacturing methods, a highly accurate variable shape mirror can be created without trouble. Therefore, in a fundus camera with an aberration compensation function that performs fundus photography through an aberration compensation optical system that compensates for wavefront aberration of the eye to be examined in the field of fundus photography and the like, aberrations can be compensated with high accuracy, and more precise. It is possible to obtain a fundus image.

  Hereinafter, another embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a cross-sectional view of the main part of the deformable mirror according to the present embodiment, and FIG. 10 is a plan view for explaining the arrangement of the electrodes of the deformable mirror according to the present embodiment.

  As shown in FIG. 9, the deformable mirror 20 includes a piezoelectric film 603, a first electrode 605 formed below the piezoelectric film 603, and a second electrode 620 formed on the piezoelectric film. A piezoelectric element 640 that is displaced by supplying a voltage from the first electrode 605 and the second electrode 620 to the piezoelectric film 603; a substrate 600 that supports the piezoelectric element 640 from below; and a substrate 600 that is formed below the substrate 600. The concave portion 611 formed, the mirror surface 650 formed above the second electrode 620, and the suppression layer 700 that suppresses deformation of the mirror surface 650 due to the weight of the mirror surface 650.

  More specifically, a metal or oxide first electrode (electrode film) 605 containing at least one of Pt, Ti, Ir, and Ru as an electrode material is formed on the substrate 600, and further on the metal or oxide. A piezoelectric film 603 containing an oxide having a perovskite structure having piezoelectricity is formed. A second electrode 620 is formed on the piezoelectric film 603.

  Moreover, the 2nd electrode 620 is formed as an electrode pattern, and can arrange | position an individual electrode in a various aspect. For example, as shown in FIG. 10, it is conceivable to arrange the individual electrodes 620a in a lattice shape. In this case, as another arrangement configuration, for example, a configuration in which individual electrodes are arranged in a plurality of (for example, three) regions arranged concentrically can be considered.

  The variable shape mirror 20 is formed with a plurality of electrode terminals (not shown), and each electrode terminal is connected to an individual electrode 620a by a wiring pattern (not shown). Thus, the first electrode 605 is electrically connected.

  The suppression layer 700 is disposed between the second electrode 620 and the mirror surface 650, and SU-8, polyimide, SIN, or the like is preferably used as the material. In addition, as a method for forming the suppression layer 700, there are a sputtering method, a CVD method, and the like. In the present embodiment, SU-8 is used as the material of the suppression layer 700, and the film thickness is about 10 to 20 μm. Note that the suppression layer 700 also serves as an insulating layer that electrically insulates between the second electrode 620 and the mirror surface 650.

Further, the shape of the mirror surface 650 formed on the suppression layer 700 and held by the suppression layer 700 is kept constant by the suppression layer 700. Thereby, deformation of the mirror surface 650 due to the weight of the mirror surface 650 is suppressed. In this case, as the material of the mirror surface 650, for example, a metal such as Au, Ag, Al, or a λ / 4 multilayer film of a low refractive index dielectric / high refractive index dielectric such as SiO ₂ / Ta ₂ O ₅ is used. Preferably used. In addition, there are many methods for forming the mirror surface 650, for example, a sputtering method or a vapor deposition method, but there is no particular limitation as long as it is a technology capable of forming a film. Moreover, as a film thickness of a mirror surface, about 1 micrometer can be considered, for example. Note that when the mirror surface 650 is formed on the suppression layer 700, it is preferable to perform planarization treatment by CMP or the like.

  As shown in FIG. 9, a part of the substrate 600 is removed at the center of the lower surface of the deformable mirror 20 so as to correspond to the second electrode 620, and a cylindrical recess 611 is formed. . Note that the recess 611 can be formed by scraping the substrate 600 from below by photolithography and etching. Due to the recess 611, the piezoelectric film 603 is easily displaced up and down.

  In the present embodiment, γ-alumina 601 is formed between the substrate 600 and the first electrode 605, and has a characteristic of improving the piezoelectric characteristics of the piezoelectric film 603. Note that the γ-alumina 601 is not necessarily provided between the substrate 600 and the first electrode 605.

  With the configuration as described above, the surface shape of the mirror surface 650 is kept constant by the suppression layer 700, so that it is possible to accurately correct aberrations by changing the shape of the mirror surface 650.

  In the above description, the mirror surface 650 is provided on the suppression layer 700. However, the mirror surface may be formed by depositing a metal such as Al on the bottom surface of the recess 611. .

  Further, when forming the mirror surface 650, as shown in FIG. 11, an elastic body (for example, PDMS) for preventing the mirror surface 650 from being bent is poured into a flat plane, and the mirror surface 650 is formed thereon. You may make it coat. FIG. 11A shows a configuration in which the mirror surface 650 is provided on the suppression layer 700, and the elastic body 800 is formed between the suppression layer 700 and the mirror surface 650. FIG. 11B shows a configuration in which a mirror surface 650 is provided on the bottom surface of the recess 611, and an elastic body 800 is formed between the bottom surface (γ-alumina 601) of the recess 611 and the mirror surface 650. The In addition, as a film thickness of the elastic body 800, about 10 micrometers is considered, for example.

It is principal part sectional drawing of the variable shape mirror which concerns on this embodiment. It is principal part sectional drawing explaining the structure of the piezoelectric actuator array which concerns on this embodiment. It is an upper schematic diagram explaining the composition of the piezoelectric actuator array concerning this embodiment. It is a figure explaining the manufacturing process of a piezoelectric actuator array. It is the upper schematic when the piezoelectric actuator which concerns on this embodiment is seen from upper direction. It is a figure explaining from the process of forming a thin film sacrificial layer in actuator array 100 to the process of forming a mirror surface. It is a figure explaining the formation position of the passage hole for dry etching formed corresponding to each piezoelectric actuator. It is a figure explaining the removal process of a thin film sacrificial layer, and the formation process of a cavity part. It is principal part sectional drawing of the variable shape mirror which concerns on this embodiment. It is a top view explaining arrangement | positioning of the electrode of the variable shape mirror which concerns on this embodiment. It is principal part sectional drawing at the time of providing an elastic body under a mirror surface.

Explanation of symbols

10, 20 Variable shape mirror 100 Piezoelectric actuator array 101 Piezoelectric actuator 102 Substrate 103 Piezoelectric film 105 First electrode 107 Second electrode 110 γ-alumina 120 First passage hole 200 Thin film sacrificial layer 250 Hole 300 Column part 500 Mirror surface 550 Second passage hole 590 Cavity 600 Substrate 601 γ-Alumina 603 Piezoelectric film 605 First electrode 611 Recess 620 Second electrode 700 Suppression layer 800 Elastic body

Claims (10)

In the manufacturing method of the variable shape mirror that changes the shape of the mirror surface,
An actuator array is prepared in which a plurality of piezoelectric actuators each having a piezoelectric film, a first electrode disposed under the piezoelectric film, and a second electrode disposed on the piezoelectric film are disposed on a substrate. A preparation process to
A sacrificial layer forming step of forming a sacrificial layer finally removed on the actuator array;
Forming a hole in the sacrificial layer so as to correspond to each of the piezoelectric actuators and exposing at least a part of the second electrode; and
A hole burying step of burying the hole formed in the sacrificial layer with a column portion material to form a column portion that supports the mirror surface on the exposed second electrode;
A planarization step of planarizing the upper surface of the sacrificial layer and the pillar portion;
A mirror surface forming step of forming a mirror surface on the upper surface of the sacrificial layer and the column portion flattened by the flattening step;
A sacrificial layer removing step of removing the sacrificial layer by an etching method after the mirror surface is formed by the mirror surface forming step;
The manufacturing method of the variable shape mirror characterized by including. In the manufacturing method of the variable shape mirror according to claim 1,
A variable shape mirror comprising: a recess forming step for forming a recess in the substrate for facilitating displacement of the piezoelectric film between the piezoelectric actuator and a substrate positioned below the piezoelectric actuator. Production method. In the manufacturing method of the variable shape mirror according to claim 2,
Forming a first passage hole through which gas for dry etching passes from the outermost surface to the substrate at each outer edge of the piezoelectric actuator;
A second passage hole forming step for forming a second passage hole through which the dry etching gas passes on the mirror surface so as to correspond to each of the piezoelectric actuators,
The sacrificial layer removing step is a step of removing the sacrificial layer by exposing the sacrificial layer to the dry etching gas through the second passage hole,
In the recess forming step, after the sacrificial layer is removed in the sacrificial layer removing step, the upper portion of the substrate is exposed to the dry etching gas through the first passage hole. A method of manufacturing a variable shape mirror, comprising a step of removing a predetermined amount and forming the concave portion between the piezoelectric actuator and a substrate. In the manufacturing method of the variable shape mirror of Claim 3,
The method of manufacturing a variable shape mirror, wherein γ-alumina is formed between the substrate and the first electrode in the piezoelectric actuator of the actuator array prepared in the preparation step. A piezoelectric film; a first electrode formed under the piezoelectric film; and a second electrode formed over the piezoelectric film, wherein the first electrode and the second electrode A piezoelectric element that is displaced by supplying a voltage to the piezoelectric film;
A substrate for supporting the piezoelectric element from below;
A recess formed on the lower side of the substrate;
A mirror surface formed above the second electrode or on the bottom surface of the recess;
A suppression layer that suppresses deformation of the mirror surface due to its own weight;
A variable shape mirror comprising: The variable shape mirror according to claim 5,
The variable shape mirror, wherein the suppression layer is made of any material of SU-8, polyimide, and SIN, and has a thickness of about 10 to 20 μm. The variable shape mirror according to claim 6,
The mirror surface is disposed on the second electrode;
The variable shape mirror, wherein the suppression layer is disposed between the second electrode and the mirror surface. The variable shape mirror according to claim 7,
A variable shape mirror, characterized in that an elastic member is provided between the mirror surface and the suppression layer to prevent deflection of the mirror surface. The variable shape mirror according to claim 5,
The mirror surface is formed on the bottom surface of the recess,
A variable shape mirror, wherein an elastic member is provided between the mirror surface and the bottom surface of the recess to prevent the mirror surface from being bent. The variable shape mirror according to claim 5,
A variable shape mirror, wherein γ-alumina is formed between the substrate and the first electrode.

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