Piezoelectrically driven micromirror and method of manufacturing

Abstract

The present application relates to a kind of piezoelectric drive micro mirror, including frame substrate (1), mirror surface (2), and two groups of motion combination beam devices that two first motion beam devices and two second motion beam devices are correspondingly combined to build, by corresponding position setting multiple piezoelectric pieces (4) on the two sides of folding beam (3), motion beam device is constituted, so by the simultaneous drive of piezoelectric piece (4) on the two sides of folding beam (3), it can obtain greater driving force, make mirror surface (2) deflect greater angle, simultaneously, using the mode of differential drive, can obtain the angle of two directions symmetry, make mirror surface (2) scanning index better, driving efficiency greatly improves, realizes the big mirror surface and big angle of rotation simultaneously with, simultaneously design realizes the manufacturing method of the piezoelectric drive micro mirror, application two pieces of SOI silicon wafer, on the basis of growth, etching, by the metal bonding between two pieces of SOI silicon wafer, piezoelectric drive micro mirror is efficiently obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to a piezoelectric drive micro-mirror and a manufacturing method, and belongs to the technical field of micro-mirrors. BACKGROUND

[0002] In long-distance laser applications, the micro-mirror needs to be able to rotate a larger angle and have a larger mirror surface, so that a larger clear aperture can be obtained; however, it is very difficult to simultaneously achieve a large mirror surface and a large rotation angle. In order to obtain a larger angle, the structural rigidity needs to be made small due to insufficient driving force, but a large mirror surface means a large mass, that is, the rigidity design is too small, and thus a large mirror surface cannot be supported, so the prior art has not yet had a product that can simultaneously achieve a large mirror surface and a large rotation angle. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a piezoelectric drive micro-mirror that adopts a double piezoelectric drive structure design and can simultaneously achieve large mirror surface and large rotation angle applications and improve actual work efficiency.

[0004] In order to solve the above technical problems, the present application adopts the following technical scheme: the present application designs a piezoelectric drive micro-mirror, which comprises a frame substrate (1), a mirror surface (2), and two first motion beam devices, wherein the structures of the two first motion beam devices are the same as each other, each first motion beam device comprises a folded beam (3) and a plurality of piezoelectric sheets (4), and in each first motion beam device structure: every two piezoelectric sheets (4) are divided into a group of piezoelectric devices, each group of piezoelectric devices is distributed in sequence along the length direction of the folded beam (3) corresponding to each position on the folded beam (3), and the adjacent two groups of piezoelectric devices are not connected to each other, the two piezoelectric sheets (4) in each group of piezoelectric devices are arranged on the upper and lower surfaces of the corresponding position of the folded beam (3), the structure of the folded beam (3) and the plurality of piezoelectric sheets (4) arranged on the surface thereof is axially symmetrical about the perpendicular bisector of the folded beam (3), and the single side direction of the symmetry axis has at least two groups of piezoelectric devices;

[0005] One side of the midpoint position of the folded beam (3) in each first motion beam device is respectively connected to two positions on the edge of the mirror surface (2) that are opposite to each other across the center of the mirror surface (2), and the other side of the midpoint position of the folded beam (3) in the two first motion beam devices is respectively connected to the frame substrate (1), based on the power supply to each piezoelectric sheet (4) in each first motion beam device, the folded beam (3) in each first motion beam device is driven to move to drive the mirror surface to rotate.

[0006] As a preferred technical scheme of the present application: further comprising two second motion beam devices with the same structure as the first motion beam device, the two first motion beam devices correspond to the two second motion beam devices one by one, forming two groups of motion combined beam devices, in each group of motion combined beam device structure: the two ends of the folding beam (3) in the first motion beam device are connected with the two ends of the folding beam (3) in the corresponding second motion beam device, the median line of the folding beam (3) in the first motion beam device is collinear with the median line of the folding beam (3) in the second motion beam device, and the overall structure of the first motion beam device and the second motion beam device is axially symmetrical with respect to the common line;

[0007] In each group of motion combined beam device, the outer side of the midpoint position of one side folding beam (3) is respectively connected to the two positions on the edge of the mirror (2) which are opposite to each other across the center of the mirror (2), and the outer side of the midpoint position of the other side folding beam (3) in each group of motion combined beam device is respectively connected to the frame substrate (1). Based on the power supply to each piezoelectric sheet (4) in each group of motion combined beam device, the folding beam (3) in the first motion beam device and the second motion beam device of each group of motion combined beam device is driven to rotate the mirror.

[0008] Corresponding to the above, the present application also designs a manufacturing method of piezoelectric driving micro mirror, based on SOI silicon wafer, using growth, etching and metal bonding, to efficiently realize the designed piezoelectric driving micro mirror.

[0009] The present application adopts the following technical scheme to solve the above technical problems: the present application designs a manufacturing method of piezoelectric driving micro mirror, comprising the following steps:

[0010] Step A. Cavity etching is performed on the surface of the first SOI silicon wafer to form a cavity;

[0011] Step B. For the position corresponding to the outside of the cavity on the surface of the first SOI silicon wafer, a method of growing and etching Au is used to build a driving electrode;

[0012] Step C. For one surface of the second SOI silicon wafer, a method of growing and etching is used to build a piezoelectric composite layer to form a piezoelectric sheet (4);

[0013] Step D. For one surface of the second SOI silicon wafer, a method of growing and etching Au is used to build a mirror (2) and a driving electrode;

[0014] Step E. With the mirror (2) growth surface of the second SOI silicon wafer facing the direction of the cavity of the first SOI silicon wafer, the second SOI silicon wafer is bonded with the first SOI silicon wafer, and each driving electrode on the second SOI silicon wafer is in contact with the corresponding position driving electrode on the first SOI silicon wafer;

[0015] Step F. A thinning operation is performed on the other surface of the second SOI silicon wafer, so that the second SOI silicon wafer meets the preset thickness;

[0016] Step G. For the other surface of the surface of the second SOI silicon wafer, a growth plus etching method is used to build a piezoelectric composite layer to form a piezoelectric sheet (4);

[0017] Step H. For the other surface of the surface of the second SOI silicon wafer, a growth plus etching Au method is used to build a mirror surface (2) and a driving electrode;

[0018] Step I. DRIE etching is performed on the second SOI silicon wafer to form a frame substrate (1), a mirror surface (2), and each motion beam device.

[0019] As a preferred technical solution of the present application: in steps C and G, a growth plus etching method is used to build a piezoelectric composite layer composed of pt / pzt / pt to form a piezoelectric sheet (4).

[0020] The piezoelectric drive micro-mirror and the manufacturing method according to the present application have the following technical effects compared with the prior art by using the above technical solution:

[0021] (1) The piezoelectric drive micro-mirror designed in the present application includes a frame substrate (1), a mirror surface (2), and two sets of motion combined beam devices composed of two first motion beam devices and two second motion beam devices corresponding to each other, and the motion beam device is formed by arranging multiple piezoelectric sheets (4) on the corresponding positions on both sides of the folded beam (3). Thus, by simultaneously driving the piezoelectric sheets (4) on both sides of the folded beam (3), a greater driving force can be obtained, and the mirror surface (2) can be deflected by a larger angle. At the same time, by using a differential driving method, the angles in the positive and negative directions can be symmetrical, so that the mirror surface (2) can be scanned better, and the driving efficiency is greatly improved. The piezoelectric drive micro-mirror is designed to have a large mirror surface and a large angle at the same time. The manufacturing method of the piezoelectric drive micro-mirror is designed to use two SOI silicon wafers. Based on growth and etching, the piezoelectric drive micro-mirror is efficiently obtained through metal bonding between the two SOI silicon wafers. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a top view of the piezoelectric drive micro-mirror designed in the present application;

[0023] Figure 2 is a test diagram of the motion beam device in the piezoelectric drive micro-mirror designed in the present application;

[0024] Figure 3 is a schematic diagram corresponding to step A in the manufacturing method of the piezoelectric drive micro-mirror designed in the present application;

[0025] Figure 4This is a schematic diagram of step B in the piezoelectrically driven micromirror manufacturing method of the present invention;

[0026] Figure 5 This is a schematic diagram of step C in the piezoelectrically driven micromirror manufacturing method of the present invention;

[0027] Figure 6 This is a schematic diagram of step D in the piezoelectrically driven micromirror manufacturing method of the present invention;

[0028] Figure 7 This is a schematic diagram of step E in the piezoelectrically driven micromirror manufacturing method of the present invention;

[0029] Figure 8 This is a schematic diagram of step F in the piezoelectrically driven micromirror manufacturing method of the present invention;

[0030] Figure 9 This is a schematic diagram of step G in the piezoelectrically driven micromirror manufacturing method of the present invention;

[0031] Figure 10 This is a schematic diagram of step H in the piezoelectrically driven micromirror manufacturing method of the present invention;

[0032] Figure 11 This is a schematic diagram of step I in the piezoelectrically driven micromirror manufacturing method of the present invention.

[0033] Among them, 1. frame substrate, 2. mirror, 3. folded beam, 4. piezoelectric sheet. Detailed Implementation

[0034] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] The piezoelectrically driven micromirror designed in this invention has practical applications, such as... Figure 1 As shown, it includes a frame substrate (1), a mirror (2), two first moving beam devices, and two second moving beam devices. The structures of the two first moving beam devices and the two second moving beam devices are the same. Each moving beam device includes a folded beam (3) and piezoelectric sheets (4). Figure 2 As shown, in each of the first moving beam device structures: every two piezoelectric pieces (4) are divided into a group of piezoelectric devices. Each group of piezoelectric devices is distributed sequentially along the length of the folded beam (3) to the corresponding positions on the folded beam (3). Adjacent groups of piezoelectric devices are not connected to each other. The two piezoelectric pieces (4) in each group of piezoelectric devices are respectively set on the upper and lower surfaces of the corresponding positions of the folded beam (3). The structure of the folded beam (3) and the piezoelectric pieces (4) set on its surface are axially symmetrical about the vertical line of the folded beam (3), and there are at least two groups of piezoelectric devices on one side of the axis of symmetry.

[0036] As shown in Figure 1 , two first motion beam devices correspond to two second motion beam devices respectively, forming two groups of motion combined beam devices, in each group of motion combined beam device structure: the two ends of the folding beam (3) in the first motion beam device are connected with the two ends of the folding beam (3) in the corresponding second motion beam device respectively, the median line of the folding beam (3) in the first motion beam device is collinear with the median line of the folding beam (3) in the second motion beam device, and the overall structure of the first motion beam device and the second motion beam device is axially symmetric with respect to the common line.

[0037] As shown in Figure 1 , the outer side of the midpoint position of one side folding beam (3) in each group of motion combined beam device is respectively connected with the two positions on the edge of the mirror (2) which are opposite to each other with respect to the center position of the mirror (2), and the outer side of the midpoint position of the other side folding beam (3) in each group of motion combined beam device is respectively connected with the frame substrate (1), based on the power supply to each segment of piezoelectric sheet (4) in each group of motion combined beam device, the folding beam (3) in the first motion beam device and the second motion beam device of each group of motion combined beam device is driven to move to drive the mirror to rotate.

[0038] In practical application, the manufacturing method of piezoelectric driving micro mirror is specifically designed, which is executed as follows.

[0039] Step A. Cavity etching is performed on the surface of the first SOI silicon wafer to form a cavity, as shown in Figure 3 ;

[0040] Step B. For the position corresponding to the outer side of the cavity on the surface of the first SOI silicon wafer, the method of growing and etching Au is used to build a driving electrode, as shown in Figure 4 ;

[0041] Step C. For one surface of the second SOI silicon wafer, the method of growing and etching is used to build a piezoelectric composite layer composed of pt / pzt / pt, which constitutes a piezoelectric sheet (4), as shown in Figure 5 ;

[0042] Step D. For one surface of the second SOI silicon wafer, the method of growing and etching Au is used to build a mirror (2) and a driving electrode, as shown in Figure 6 ;

[0043] Step E. The second SOI silicon wafer is bonded to the first SOI silicon wafer with the growth surface of the mirror (2) on the surface of the second SOI silicon wafer facing the cavity of the first SOI silicon wafer, and each driving electrode on the second SOI silicon wafer is in contact with the corresponding position driving electrode on the first SOI silicon wafer, as shown in Figure 7 ;

[0044] Step F. A thinning operation is performed on the other surface of the second SOI silicon wafer, so that the second SOI silicon wafer meets a preset thickness, as shown in Figure 8 ;

[0045] Step G. For the other surface of the surface of the second SOI silicon wafer, a piezoelectric composite layer composed of pt / pzt / pt is constructed by a growth plus etching method, to form a piezoelectric sheet (4), as shown in Figure 9 ;

[0046] Step H. For the other surface of the surface of the second SOI silicon wafer, a mirror surface (2) and a driving electrode are constructed by a growth plus etching Au method, as shown in Figure 10 ;

[0047] Step I. DRIE etching is performed on the second SOI silicon wafer, to form a frame substrate (1), a mirror surface (2), and each motion beam device, as shown in Figure 11 .

[0048] The piezoelectric driving micro mirror designed by the above technical solution comprises a frame substrate (1), a mirror surface (2), and two groups of motion combined beam devices composed of two first motion beam devices and two second motion beam devices corresponding to each other, a plurality of piezoelectric sheets (4) are arranged at corresponding positions on both sides of the folded beam (3) to form the motion beam device, so that a greater driving force can be obtained by simultaneously driving the piezoelectric sheets (4) on both sides of the folded beam (3), and the mirror surface (2) can be deflected by a larger angle. At the same time, by using a differential driving method, angles in two directions can be obtained, so that the mirror surface (2) can be better scanned, the driving efficiency is greatly improved, and the piezoelectric driving micro mirror with a large mirror surface and a large angle is realized at the same time. A manufacturing method of the piezoelectric driving micro mirror is also designed, two SOI silicon wafers are used, and the piezoelectric driving micro mirror is efficiently obtained through metal bonding between the two SOI silicon wafers on the basis of growth and etching.

[0049] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application.

Claims

1. A piezoelectrically actuated micro-mirror, characterized by: The application relates to a mirror frame structure, which comprises a frame substrate (1), a mirror surface (2) and two first motion beam devices, wherein the two first motion beam devices are identical in structure, each first motion beam device comprises a folding beam (3) and a plurality of piezoelectric pieces (4), and each first motion beam device is structured as follows: every two piezoelectric pieces (4) are divided into a group of piezoelectric devices, the groups of piezoelectric devices are sequentially distributed on the folding beam (3) corresponding to the positions of the folding beam (3) in the length direction, and the adjacent two groups of piezoelectric devices are not connected to each other, the two piezoelectric pieces (4) in each group of piezoelectric devices are arranged on the upper and lower surfaces of the corresponding position of the folding beam (3), the folding beam (3) and the piezoelectric pieces (4) arranged on the surfaces of the folding beam (3) are axially symmetrical about the median line of the folding beam (3), and at least two groups of piezoelectric devices are arranged on one side of the symmetry axis; one side of the midpoint of the folding beam (3) in each first motion beam device is connected to two positions on the edge of the mirror surface (2) which are opposite to each other and pass through the center of the mirror surface (2), and the other side of the midpoint of the folding beam (3) in the two first motion beam devices is connected to the frame substrate (1); the folding beam (3) in each first motion beam device is driven to move and drive the mirror surface to rotate based on the power supply of the piezoelectric pieces (4) in each first motion beam device. The application further comprises two second motion beam devices which are identical in structure to the first motion beam devices, the two first motion beam devices are one-to-one corresponding to the two second motion beam devices, and the two first motion beam devices and the two second motion beam devices form two groups of motion combination beam devices, wherein the two ends of the folding beam (3) in the first motion beam device are connected to the two ends of the folding beam (3) in the corresponding second motion beam device, the median lines of the folding beams (3) in the first motion beam device and the second motion beam device are collinear, and the overall structure of the first motion beam device and the second motion beam device is axially symmetrical about the collinear line; the outer side of the midpoint of the folding beam (3) on one side in each group of motion combination beam devices is connected to two positions on the edge of the mirror surface (2) which are opposite to each other and pass through the center of the mirror surface (2), the outer side of the midpoint of the folding beam (3) on the other side in each group of motion combination beam devices is connected to the frame substrate (1), and the folding beams (3) in the first motion beam device and the second motion beam device in each group of motion combination beam devices are driven to move and drive the mirror surface to rotate based on the power supply of the piezoelectric pieces (4) in each group of motion combination beam devices. The application further comprises the following steps: Step A: cavity etching is performed on the surface of a first SOI silicon wafer to form a cavity; 2. A method for manufacturing a piezoelectrically driven micro-mirror according to claim 1, characterized by, Step B: a driving electrode is constructed by growing and etching Au on the positions corresponding to the outer side of the cavity on the surface of the first SOI silicon wafer; Step C: a piezoelectric composite layer is constructed by growing and etching on one surface of a second SOI silicon wafer to form a piezoelectric piece (4); Step D: a mirror surface (2) and a driving electrode are constructed by growing and etching Au on one surface of the second SOI silicon wafer. ​ ​ Step E. Bonding the second SOI silicon wafer with the first SOI silicon wafer in the direction of the mirror surface (2) growth surface of the second SOI silicon wafer facing the cavity of the first SOI silicon wafer, and the driving electrodes on the second SOI silicon wafer contacting the driving electrodes at the corresponding positions on the first SOI silicon wafer; Step F. Thinning the other surface of the second SOI silicon wafer to meet the preset thickness; Step G. For the other surface of the second SOI silicon wafer, a growth and etching method is used to build a piezoelectric composite layer to form a piezoelectric sheet (4); Step H. For the other surface of the second SOI silicon wafer, a growth and etching Au method is used to build a mirror surface (2) and driving electrodes; Step I. DRIE etching is performed on the second SOI silicon wafer to form a frame substrate (1), a mirror surface (2), and each motion beam device.

3. The method of claim 2, wherein the piezoelectric actuator is formed by the steps of: In steps C and G, a growth and etching method is used to build a piezoelectric composite layer composed of pt / pzt / pt to form a piezoelectric sheet (4). ​

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