Two-dimensional biaxial piezoelectric MEMS micromirror

Abstract

The invention relates to a two-dimensional biaxial piezoelectric MEMS (Micro Electro Mechanical System) micromirror, belongs to the technical field of semiconductor equipment, and solves the problem that the MEMS micromirror in the prior art cannot be overturned at a large angle. The MEMS micromirror comprises a silicon wafer substrate, and a reflecting mirror surface and N cantilever beams which are formed by etching on the silicon wafer substrate, and N is 2 or 4; the N cantilever beams are symmetrically arranged on the periphery of the reflecting mirror surface, the fixed ends of the N cantilever beams are integrally connected with the silicon wafer substrate, and the free ends of the N cantilever beams are integrally connected with the reflecting mirror surface; the fixed ends are uniformly distributed on the silicon wafer substrate, and the free ends are uniformly distributed on the reflecting mirror surface; each cantilever beam is provided with a piezoelectric driving block, after the piezoelectric driving blocks are powered on, the piezoelectric driving blocks drive the cantilever beams to bend, and the bending of the cantilever beams drives the reflection mirror surface to turn over. And the large-angle overturning of the MEMS micro-mirror during working is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor equipment, and in particular to a two-dimensional dual-axis piezoelectric MEMS micromirror. Background Art

[0002] At present, laser radar can be divided into three categories according to its structure: mechanical laser radar, solid-state laser radar and hybrid solid-state laser radar. According to its working dimension, it can be divided into one-dimensional, two-dimensional and three-dimensional laser radar. Mechanical laser radar controls the angle of laser emission by rotating the transmitter, and is large in size and expensive. Solid-state laser radar uses electronic devices instead of mechanical rotating parts to control the angle of the laser beam, which greatly reduces the size of the laser radar and reduces the manufacturing cost. Before 2007, the main development direction of laser radar was mechanical laser radar. After 2008, it was committed to the research of low-cost and small-size laser radar. Solid-state laser radar came into being, and laser radar has also developed rapidly since then.

[0003] MEMS (Micro-Electro-Mechanical System) LiDAR is a solid-state LiDAR that uses a MEMS scanning mirror as a laser beam scanning element. MEMS LiDAR has been widely used in UAV active cruise control systems (airborne) and unmanned target recognition (vehicle-mounted) and other environments.

[0004] The laser radar system based on MEMS scanning mirror mainly includes a light-projecting unit, a light-receiving unit and a control system. The light-projecting unit is mainly used to complete the emission of the laser beam and the expansion of the beam angle. The light-receiving unit is mainly suitable for receiving the light waves reflected by the object and handing them over to the control system for processing. The light-projecting unit includes a laser, a collimation system and a MEMS scanning mirror. The collimation system is used to reduce the divergence angle of the laser-emitted light beam, and the MEMS scanning mirror is used to expand the scanning range of the collimated light beam. When the laser radar is working, the control system sends a control signal to the laser. After receiving the control signal, the laser will emit a corresponding pulsed laser. After being collimated by the collimation system, it will be incident on the reflective mirror surface of the MEMS scanning mirror. The MEMS scanning mirror is driven to work by controlling the internal driver to change the direction of the outgoing light beam and scan the target object.

[0005] Although the existing piezoelectric MEMS micromirrors have the characteristics of low driving power, high control accuracy, wide operating frequency, and good process compatibility, they cannot obtain a good scanning angle due to the problem of small piezoelectric driving displacement, making it impossible for the MEMS micromirrors to flip at a large angle when working. Summary of the invention

[0006] In view of the above analysis, an embodiment of the present invention aims to provide a two-dimensional dual-axis piezoelectric MEMS micromirror to solve the problem in the prior art that the MEMS micromirror cannot be flipped at a large angle.

[0007] The embodiment of the present invention provides a two-dimensional biaxial piezoelectric MEMS micromirror, wherein the MEMS micromirror comprises a silicon wafer substrate, a reflective mirror surface etched on the silicon wafer substrate, and N cantilever beams, where N is 2 or 4;

[0008] The N cantilever beams are symmetrically arranged around the periphery of the reflective mirror, the fixed ends of the N cantilever beams are integrally connected to the silicon wafer substrate, and the free ends are integrally connected to the reflective mirror;

[0009] The fixed ends are evenly arranged on the silicon wafer substrate, and the free ends are evenly arranged on the reflective mirror surface;

[0010] A piezoelectric drive block is arranged on each cantilever beam. After power is turned on, the piezoelectric drive block drives the cantilever beam to bend, and the bending of the cantilever beam drives the reflection mirror to flip.

[0011] Based on the further improvement of the above two-dimensional biaxial piezoelectric MEMS micromirror, the cantilever beam is any one of an L-shaped cantilever beam, a folded L-shaped cantilever beam, a Z-shaped cantilever beam, a folded C-shaped cantilever beam and a nested C-shaped cantilever beam.

[0012] Based on the further improvement of the above two-dimensional dual-axis piezoelectric MEMS micromirror, each piezoelectric driving block includes a piezoelectric material lower metal electrode, a piezoelectric material and a piezoelectric material upper metal electrode arranged in sequence from bottom to top.

[0013] Based on the further improvement of the above two-dimensional biaxial piezoelectric MEMS micromirror, when the cantilever beam is an L-shaped cantilever beam, N is 4, each L-shaped cantilever beam includes a first strip segment and a second strip segment, one end of the first strip segment is a fixed end, and the other end is connected to one end of the second strip segment, and the other end of the second strip segment is a free end;

[0014] The first strip segment and the second strip segment are perpendicular to each other to form an L shape;

[0015] The first strip section of each L-shaped cantilever beam is arranged on the periphery of the second strip section of the previous L-shaped cantilever beam, and the second strip section of each L-shaped cantilever beam is arranged on the inner periphery of the first strip section of the next L-shaped cantilever beam, and the four L-shaped cantilever beams form a square.

[0016] Based on the further improvement of the above two-dimensional biaxial piezoelectric MEMS micromirror, when the cantilever beam is a folded L-shaped cantilever beam, N is 2, and each folded L-shaped cantilever beam includes a third strip segment, a fourth strip segment, a fifth strip segment and a sixth strip segment, one end of the third strip segment is a fixed end, and the other end is connected to one end of the fourth strip segment, the other end of the fourth strip segment is connected to one end of the fifth strip segment, the other end of the fifth strip segment is connected to one end of the sixth strip segment, and the other end of the sixth strip segment is a free end;

[0017] The third strip segment and the fourth strip segment are perpendicular to each other to form an L-shape, the fifth strip segment and the sixth strip segment are perpendicular to each other to form an L-shape, and the fourth strip segment and the fifth strip segment are parallel to each other to form a folded L-shaped cantilever beam.

[0018] Based on the further improvement of the above two-dimensional biaxial piezoelectric MEMS micromirror, when the cantilever beam is a Z-shaped cantilever beam, N is 2, each Z-shaped cantilever beam includes a first arc segment and a second arc segment, one end of the first arc segment is a fixed end, and the other end is connected to one end of the second arc segment, and the other end of the second arc segment is a free end;

[0019] The central angles of the first arc segment and the second arc segment are both 180°;

[0020] The first arc segment of each Z-shaped cantilever beam is arranged on the periphery of the second arc segment of another Z-shaped cantilever beam.

[0021] Based on the further improvement of the above two-dimensional biaxial piezoelectric MEMS micromirror, when the cantilever beam is a folded C-type cantilever beam, N is 2, each folded C-type cantilever beam includes a third arc segment and a fourth arc segment, one end of the third arc segment is a fixed end, and the other end is connected to one end of the fourth arc segment, and the other end of the fourth arc segment is a free end;

[0022] The central angles of the third arc segment and the fourth arc segment are both 180°;

[0023] The third arc segment of each folded C-shaped cantilever beam is arranged on the periphery of the fourth arc segment.

[0024] Based on the further improvement of the above two-dimensional biaxial piezoelectric MEMS micromirror, when the cantilever beam is a nested C-type cantilever beam, N is 2, and each nested C-type cantilever beam includes a fifth arc segment, a sixth arc segment and a circular ring connecting segment, wherein two nested C-type cantilever beams share the same circular ring connecting segment;

[0025] The annular connecting section includes two outer ends and two inner ends, and is evenly arranged on the silicon wafer substrate;

[0026] The central angles of the fifth arc segment and the sixth arc segment are both 180°;

[0027] One end of the fifth arc segment of each nested C-shaped cantilever beam is a fixed end, and the other end is connected to the outer end of the circular connecting segment. The inner end of the circular connecting segment is connected to one end of the sixth arc segment, and the other end of the sixth arc segment is a free end.

[0028] Based on the further improvement of the above two-dimensional biaxial piezoelectric MEMS micromirror, the piezoelectric material is any one of the following: barium titanate BT, lead zirconate titanate PZT, modified lead zirconate titanate, lead metaniobate, lead barium lithium niobate PBLN and modified lead titanate PT.

[0029] Based on the further improvement of the above two-dimensional biaxial piezoelectric MEMS micromirror, the width of the cantilever beam is 30um-300um.

[0030] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0031] 1. The present invention connects the fixed ends of N cantilever beams to the silicon wafer substrate, and the free ends to the reflective mirror. Each cantilever beam is provided with a plurality of piezoelectric drive blocks. After power-on, the plurality of piezoelectric drive blocks interact with each other to drive the cantilever beam to bend, and the bending of the cantilever beam drives the reflective mirror to flip at a large angle.

[0032] 2. The present invention makes the MEMS micromirror more integrated and occupies a smaller volume by virtue of the MEMS micromirror including a silicon wafer substrate, a reflective mirror surface etched on the silicon wafer substrate, and N cantilever beams.

[0033] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the following description, and some advantages can be obvious from the description or understood by practicing the present invention. The purpose and other advantages of the present invention can be described in detail.

[0034] The present invention can be realized and obtained by referring to the contents particularly pointed out in the book and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0036] Figure 1 A schematic diagram of the top view structure of a two-dimensional biaxial piezoelectric MEMS micromirror with an L-shaped cantilever beam provided in an embodiment of the present invention;

[0037] Figure 2 A schematic diagram of the cross-sectional structure of a two-dimensional biaxial piezoelectric MEMS micromirror provided in an embodiment of the present invention;

[0038] Figure 3A schematic diagram of the three-dimensional structure of a two-dimensional biaxial piezoelectric MEMS micromirror of an L-shaped cantilever beam provided in an embodiment of the present invention;

[0039] Figure 4 A schematic diagram of the top view structure of a two-dimensional biaxial piezoelectric MEMS micromirror with a folded L-shaped cantilever beam provided in an embodiment of the present invention;

[0040] Figure 5 A schematic diagram of the three-dimensional structure of a two-dimensional biaxial piezoelectric MEMS micromirror with a folded L-shaped cantilever beam provided in an embodiment of the present invention;

[0041] Figure 6 A schematic diagram of the top view structure of a two-dimensional biaxial piezoelectric MEMS micromirror with a Z-shaped cantilever beam provided in an embodiment of the present invention;

[0042] Figure 7 A schematic diagram of the three-dimensional structure of a two-dimensional biaxial piezoelectric MEMS micromirror of a Z-shaped cantilever beam provided in an embodiment of the present invention;

[0043] Figure 8 A schematic diagram of the top view structure of a two-dimensional biaxial piezoelectric MEMS micromirror with a folded C-shaped cantilever beam provided in an embodiment of the present invention;

[0044] Fig. 9 A schematic diagram of the three-dimensional structure of a two-dimensional biaxial piezoelectric MEMS micromirror with a folded C-shaped cantilever beam provided in an embodiment of the present invention;

[0045] Fig.10 A schematic diagram of the top view structure of a two-dimensional biaxial piezoelectric MEMS micromirror with a nested C-shaped cantilever beam provided in an embodiment of the present invention;

[0046] Fig.11 A schematic diagram of the three-dimensional structure of a two-dimensional biaxial piezoelectric MEMS micromirror with a nested C-shaped cantilever beam provided in an embodiment of the present invention;

[0047] Fig.12 A schematic diagram of structural changes in the first major step of a method for manufacturing a two-dimensional biaxial piezoelectric MEMS micromirror provided by an embodiment of the present invention;

[0048] Fig.13 A schematic diagram of the structural changes in the second major step of a method for manufacturing a two-dimensional biaxial piezoelectric MEMS micromirror provided in an embodiment of the present invention.

[0049] Reference numerals:

[0050] 1-silicon wafer substrate; 2-cantilever beam;

[0051] 3-metal electrode under the piezoelectric material; 4-piezoelectric material; 5-metal electrode on the upper layer of the piezoelectric material;

[0052] 6-reflecting mirror; 7-piezoelectric driving block; 8-first strip segment;

[0053] 9- the second strip segment; 10- the third strip segment; 11- the fourth strip segment;

[0054] 12-fifth strip segment; 13-sixth strip segment; 14-first arc segment;

[0055] 15-second arc segment; 16-third arc segment; 17-fourth arc segment;

[0056] 18-fifth arc segment; 19-sixth arc segment; 20-circular connecting segment;

[0057] 21-outer end; 22-inner end;

[0058] A1, A2, A3, A4, A5, A6-fixed end;

[0059] B1, B2, B3, B4, B5, B6 - free ends;

[0060] C1-SOI wafer; C2-SiO2 protective layer; C3-lower electrode layer;

[0061] C4-piezoelectric material layer; C5-upper electrode layer;

[0062] D1-Si device layer; D2-SiO2 buried oxide layer; D3-Si supporting layer; D4-SiO2 bottom layer. DETAILED DESCRIPTION

[0063] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0064] Existing MEMS micromirror drive modes include piezoelectric drive. Piezoelectric drive MEMS scanning mirrors use piezoelectric materials as the driver of the scanning mirror, and drive the MEMS micromirror deflection through the piezoelectric driver. The piezoelectric driver is driven based on the piezoelectric effect of the piezoelectric material. Its basic principle is: the piezoelectric material itself has a polarization voltage. Depending on whether the direction of the applied voltage is consistent with the polarization voltage, the piezoelectric material is stretched or shortened. The elongation and shortening of the piezoelectric material is used to drive the scanning mirror to move together, thereby producing the effect of displacement and deflection.

[0065] The laser radar system based on MEMS scanning mirror mainly includes a light-projecting unit, a light-receiving unit and a control system. The light-projecting unit is mainly used to complete the emission of the laser beam and the expansion of the beam angle. The light-receiving unit is mainly suitable for receiving the light waves reflected by the object and handing them over to the control system for processing. The light-projecting unit includes a laser, a collimation system and a MEMS scanning mirror. The collimation system is used to reduce the divergence angle of the laser-emitted light beam, and the MEMS scanning mirror is used to expand the scanning range of the collimated light beam. When the laser radar is working, the control system sends a control signal to the laser. After receiving the control signal, the laser will emit a corresponding pulsed laser. After being collimated by the collimation system, it will be incident on the reflective mirror surface of the MEMS scanning mirror. The MEMS scanning mirror is driven to work by controlling the internal driver to change the direction of the outgoing light beam and scan the target object.

[0066] The MEMS micromirror structure shown in the present invention, the piezoelectric MEMS micromirror can not only achieve a large mechanical deflection angle, but also can achieve two-dimensional plane scanning, which can further reduce the volume of the traditional piezoelectric MEMS scanning mirror, make the volume of the manufactured sensor and actuator smaller, and further achieve the goal of miniaturization.

[0067] Example 1

[0068] A specific embodiment of the present invention discloses a two-dimensional biaxial piezoelectric MEMS micromirror, such as Figure 1 , Figure 2 and Figure 3 As shown, the MEMS micromirror comprises a silicon wafer substrate 1, a reflective mirror surface 6 formed by etching on the silicon wafer substrate 1, and N cantilever beams 2, where N is 2 or 4;

[0069] The N cantilever beams 2 are symmetrically arranged around the reflective mirror surface 6, the fixed ends of the N cantilever beams 2 are integrally connected to the silicon wafer substrate 1, and the free ends are integrally connected to the reflective mirror surface 6;

[0070] The fixed ends are evenly arranged on the silicon wafer substrate 1, and the free ends are evenly arranged on the reflective mirror surface 6;

[0071] A piezoelectric driving block 7 is arranged on each cantilever beam 2. After power is turned on, the piezoelectric driving block 7 drives the cantilever beam 2 to bend, and the bending of the cantilever beam 2 drives the reflective mirror 6 to flip.

[0072] Specifically, Figure 1 and Figure 3 As shown, the MEMS micromirror includes a silicon wafer substrate 1 , four cantilever beams 2 , a reflective mirror surface 6 and a piezoelectric drive block 7 , and two piezoelectric drive blocks 7 are arranged on each cantilever beam 2 .

[0073] Furthermore, the four cantilever beams 2, the reflective mirror surface 6 and the piezoelectric drive block 7 are all formed by etching on the silicon wafer substrate 1. The cross-sectional view of the MEMS micromirror is shown in FIG. Figure 2 As shown; the specific implementation method will be described in detail in the following embodiment 2.

[0074] Specifically, Figure 1 and Figure 3 As shown, four cantilever beams 2 are symmetrically arranged on the periphery of the reflective mirror surface 6 . It can be understood that the fixed ends of the four cantilever beams 2 are symmetrically arranged around the center of the reflective mirror surface 6 , and the free ends of the four cantilever beams 2 are symmetrically arranged around the center of the reflective mirror surface 6 .

[0075] It is worth noting that in the same MEMS micromirror, the cantilever beams 2 have the same shape. The fixed ends of the four cantilever beams 2 are integrally connected to the silicon wafer substrate 1, and the free ends are integrally connected to the reflective mirror surface 6. The fixed ends are evenly arranged on the silicon wafer substrate 1, and the free ends are evenly arranged on the reflective mirror surface 6.

[0076] Specifically, Figure 1 and Figure 3 As shown, two piezoelectric drive blocks 7 are arranged on each cantilever beam 2. After power-on, the two piezoelectric drive blocks 7 drive the cantilever beam 2 to bend, and the bending of the cantilever beam 2 drives the reflective mirror 6 to flip, thereby realizing two-dimensional biaxial rotation of the MEMS micromirror in the horizontal and vertical directions, and realizing two-dimensional scanning of the object.

[0077] Preferably, if Figure 2 As shown, each piezoelectric driving block 7 includes a piezoelectric material lower metal electrode 3, a piezoelectric material 4 and a piezoelectric material upper metal electrode 5 which are arranged in sequence from bottom to top.

[0078] Preferably, if Figure 1 and Figure 3 As shown, the width of the cantilever beam is 30um-300um, which can meet the working conditions under different working frequencies.

[0079] It is worth noting that the area utilization rate of the MEMS micromirror structure provided by the present invention is also very high compared with the prior art.

[0080] In a MEMS micromirror, the area occupied by the reflective mirror surface 6 is between one sixth and one quarter, so that the MEMS micromirror has a higher integration degree and occupies a smaller volume.

[0081] Preferably, the piezoelectric material is any one of the following: barium titanate BT, lead zirconate titanate PZT, modified lead zirconate titanate, lead metaniobate, lead barium lithium niobate PBLN and modified lead titanate PT. In practical applications, different types of piezoelectric materials can be selected according to different work requirements.

[0082] Preferably, the cantilever beam is any one of an L-shaped cantilever beam, a folded L-shaped cantilever beam, a Z-shaped cantilever beam, a folded C-shaped cantilever beam and a nested C-shaped cantilever beam.

[0083] Specifically, Figure 1 and Figure 3 As shown, when the cantilever beam 2 is an L-shaped cantilever beam, N is 4, and each L-shaped cantilever beam 2 includes a first strip segment 8 and a second strip segment 9, one end of the first strip segment 8 is a fixed end, and the other end is connected to one end of the second strip segment 9, and the other end of the second strip segment 9 is a free end;

[0084] The first strip segment 8 and the second strip segment 9 are perpendicular to each other to form an L shape;

[0085] The first strip segment 8 of each L-shaped cantilever beam 2 is arranged on the periphery of the second strip segment 9 of the previous L-shaped cantilever beam 2, and the second strip segment 9 of each L-shaped cantilever beam 2 is arranged on the inner periphery of the first strip segment 8 of the next L-shaped cantilever beam 2, and the four L-shaped cantilever beams 2 form a square.

[0086] It can be understood that a piezoelectric driving block 7 can be set on each of the first strip segment 8 and the second strip segment 9. Since the first strip segment 8 and the second strip segment 9 belong to a whole, when power is turned on, the piezoelectric driving blocks 7 on the first strip segment 8 and the second strip segment 9 jointly drive the free end of the second strip segment 9, and then drive the reflecting mirror 6 integrally connected to the free end to flip.

[0087] Specifically, Figure 1 As shown in FIG. 1 , when the reflective mirror surface 6 needs to be flipped in the horizontal direction, the L-shaped cantilever beams 2 where A1 and B1 are located, and the L-shaped cantilever beams 2 where A4 and B4 are located are used as the first group, and the L-shaped cantilever beams 2 where A2 and B2 are located, and the L-shaped cantilever beams 2 where A3 and B3 are located are used as the second group; when the power is turned on, the voltage pole input by the piezoelectric drive block 7 set on the first group of L-shaped cantilever beams 2 is

[0088] The polarity and size of the piezoelectric drive block 7 provided on the second group of L-shaped cantilever beams 2 are the same, and the corresponding free ends B1 and B4 are driven to move to the same height respectively. The voltage polarity inputted by the piezoelectric drive block 7 provided on the second group of L-shaped cantilever beams 2 is opposite to that of the first group, and the size is the same, and the corresponding free ends B2 and B3 are driven to move to the same height in the opposite direction to that of the first group. It is worth noting that, with the cooperation between the first group and the second group, the reflective mirror surface is flipped in the horizontal direction.

[0089] Specifically, Figure 1As shown, when the reflective mirror 6 needs to be flipped in the vertical direction, the L-shaped cantilever beams 2 where A1 and B1 are located, and the L-shaped cantilever beams 2 where A2 and B2 are located are used as the first group, and the L-shaped cantilever beams 2 where A3 and B3 are located, and the L-shaped cantilever beams 2 where A4 and B4 are located are used as the second group; when powered on, the voltage inputted by the piezoelectric drive block 7 set on the first group of L-shaped cantilever beams 2 has the same polarity and the same magnitude, and the corresponding free ends B1 and B4 are driven to move to the same height respectively, and the voltage inputted by the piezoelectric drive block 7 set on the second group of L-shaped cantilever beams 2 has the opposite polarity and the same magnitude to the first group, and the corresponding free ends B2 and B3 are driven to move to the same height in the opposite direction to the first group respectively. It is worth noting that with the cooperation between the first group and the second group, the reflective mirror is flipped in the vertical direction.

[0090] Specifically, Figure 4 and Figure 5 As shown, when the cantilever beam 2 is a folded L-shaped cantilever beam, N is 2, and each folded L-shaped cantilever beam 2 includes a third strip segment 10, a fourth strip segment 11, a fifth strip segment 12 and a sixth strip segment 13, one end of the third strip segment 10 is a fixed end, and the other end is connected to one end of the fourth strip segment 11, the other end of the fourth strip segment 11 is connected to one end of the fifth strip segment 12, the other end of the fifth strip segment 12 is connected to one end of the sixth strip segment 13, and the other end of the sixth strip segment 13 is a free end;

[0091] The third strip segment 10 and the fourth strip segment 11 are perpendicular to each other to form an L shape, the fifth strip segment 12 and the sixth strip segment 13 are perpendicular to each other to form an L shape, and the fourth strip segment 11 and the fifth strip segment 12 are parallel to each other, and together form a folded L-shaped cantilever beam 2.

[0092] It is understandable that each folded L-shaped

[0093] The cantilever beam 2 may include four piezoelectric drive blocks 7, that is, a piezoelectric drive block 7 is respectively provided for the third strip segment 10, the fourth strip segment 11, the fifth strip segment 12 and the sixth strip segment 13 of each folded L-shaped cantilever beam 2. Then, each folded L-shaped cantilever beam 2, driven by the four piezoelectric drive blocks 7, drives the reflective mirror 6 integrally connected to the free end of the sixth strip segment 13 to flip.

[0094] Specifically, Figure 4As shown, when the reflective mirror surface 6 needs to be flipped in the horizontal direction, the drive blocks 10 and 13 on the L-shaped cantilever beam 2 where A5 and B5 are located are used as the first group, and the drive blocks 10 and 13 on the L-shaped cantilever beam 2 where A6 and B6 are located are used as the second group; when powered on, the voltages inputted by the piezoelectric drive blocks 10 and 13 set on the first group of folded L-shaped cantilever beams 2 have opposite polarities and the same magnitude, driving the corresponding free end B5 to move to the same height, and the voltages inputted by the piezoelectric drive blocks 10 and 13 set on the second group of folded L-shaped cantilever beams 2 have opposite polarities and the same magnitude as the first group, driving the corresponding free end B6 to move to the same height in the opposite direction to the first group. It is worth noting that, with the cooperation of the first group and the second group, the reflective mirror surface is flipped in the horizontal direction.

[0095] Specifically, Figure 4 As shown, when the reflective mirror surface 6 needs to be flipped in the vertical direction, the drive blocks 11 and 12 on the L-shaped cantilever beam 2 where A5 and B5 are located are used as the first group, and the drive blocks 11 and 12 on the L-shaped cantilever beam 2 where A6 and B6 are located are used as the second group; when powered on, the voltages inputted by the piezoelectric drive blocks 11 and 12 set on the first group of folded L-shaped cantilever beams 2 have opposite polarities and the same magnitude, driving the corresponding free end B5 to move to the same height, and the voltages inputted by the piezoelectric drive blocks 11 and 12 set on the second group of folded L-shaped cantilever beams 2 have opposite polarities and the same magnitude as the first group, driving the corresponding free end B6 to move to the same height in the opposite direction to the first group. It is worth noting that, with the cooperation of the first group and the second group, the reflective mirror surface is flipped in the vertical direction.

[0096] Specifically, Figure 6 and Figure 7 As shown, when the cantilever beam 2 is a Z-shaped cantilever beam 2, N is 2, and each Z-shaped cantilever beam 2 includes a first arc segment 14 and a second arc segment 15, one end of the first arc segment 14 is a fixed end, and the other end is connected to one end of the second arc segment 15, and the other end of the second arc segment 15 is a free end;

[0097] The central angles of the first arc segment 14 and the second arc segment 15 are both 180°;

[0098] The first arc segment 14 of each Z-shaped cantilever beam is disposed on the periphery of the second arc segment 15 of another Z-shaped cantilever beam 2 .

[0099] It can be understood that each Z-shaped cantilever beam 2 includes two arc segments, the first arc segment 14 and the second arc segment 15, which can both be provided with a piezoelectric drive block 7, and each strip segment can be provided with two piezoelectric drive blocks 7, such as Figure 6 and Figure 7As shown, two piezoelectric drive blocks 7 are arranged on each first arc segment 14, and two piezoelectric drive blocks 7 are arranged on each second arc segment. It is worth noting that only one piezoelectric drive block 7 may be arranged on each arc segment of each Z-shaped cantilever beam 2.

[0100] Each Z-shaped cantilever beam 2, driven by the piezoelectric drive block 7 of the first arc segment 14 and the second arc segment 15, drives the reflective mirror 6 integrally connected to the free end of the other end of the second arc segment 15 to flip.

[0101] Specifically, Figure 8 and Fig. 9 As shown, when the cantilever beam 2 is a folded C-shaped cantilever beam 2, N is 2, and each folded C-shaped cantilever beam 2 includes a third arc segment 16 and a fourth arc segment 17, one end of the third arc segment 16 is a fixed end, and the other end is connected to one end of the fourth arc segment 17, and the other end of the fourth arc segment 17 is a free end;

[0102] The central angles of the third arc segment 16 and the fourth arc segment 17 are both 180°;

[0103] The third arc segment 16 of each folded C-shaped cantilever beam 2 is arranged on the periphery of the fourth arc segment 17 .

[0104] It can be understood that the two arc segments included in each folded C-shaped cantilever beam 2, the third arc segment 16 and the fourth arc segment 17 can each be provided with two piezoelectric drive blocks 7, such as Figure 8 and Fig. 9 As shown, two piezoelectric drive blocks 7 are provided for each third arc segment, and two piezoelectric drive blocks 7 are provided for each fourth arc segment. It is worth noting that one piezoelectric drive block 7 can also be provided on each arc segment of each folded C-shaped cantilever beam 2, that is, one piezoelectric drive block is provided for each third arc segment 16 and the fourth arc segment 17.

[0105] Each folded C-shaped cantilever beam 2, driven by the piezoelectric drive blocks 7 provided in the third arc segment 16 and the fourth arc segment 17, drives the reflective mirror surface 6 at the free end of the other end of the fourth arc segment 17 to flip.

[0106] Specifically, Fig.10 and Fig.11 As shown, when the cantilever beam 2 is a nested C-type cantilever beam 2, N is 2, and each nested C-type cantilever beam 2 includes a fifth arc segment 18, a sixth arc segment 19 and a circular ring connecting segment 20, wherein two nested C-type cantilever beams share the same circular ring connecting segment;

[0107] The annular connecting section 20 includes two outer ends 21 and two inner ends 22, and is evenly arranged on the silicon wafer substrate;

[0108] The central angles of the fifth arc segment 18 and the sixth arc segment 19 are both 180°;

[0109] One end of the fifth arc segment 18 of each nested C-shaped cantilever beam 2 is a fixed end, and the other end is connected to the outer end 21 of the circular connecting segment 20. The inner end 22 of the circular connecting segment 20 is connected to one end of the sixth arc segment 19, and the other end of the sixth arc segment 19 is a free end.

[0110] It can be understood that, on the two arc segments of each nested C-shaped cantilever beam 2, two piezoelectric drive blocks 7 can be set on the fifth arc segment 18 and the sixth arc segment 19, such as Fig.10 and Fig.11 As shown, two piezoelectric drive blocks 7 are arranged on the fifth arc segment 18, and two piezoelectric drive blocks 7 are arranged on the sixth arc segment 19. It is worth noting that only one piezoelectric drive block 7 can be arranged on each nested C-shaped cantilever beam 2, and one piezoelectric drive block 7 is arranged on each of the fifth arc segment 18 and the sixth arc segment 19.

[0111] Each nested C-shaped cantilever beam 2, driven by the piezoelectric drive block 7 provided in the fifth arc segment 18 and the sixth arc segment 19, drives the reflective mirror 6 integrally connected to the free end of the other end of the sixth arc segment 19 to flip.

[0112] Preferably, the MEMS micromirror further includes a SiO2 protective layer, which is disposed on the cantilever beam 2 to protect the cantilever beam 2, and the piezoelectric driving block 7 is disposed on the SiO2 protective layer.

[0113] Compared with the prior art, the two-dimensional biaxial piezoelectric MEMS micromirror provided in this embodiment is integrally connected to the silicon wafer substrate through the fixed ends of N cantilever beams, and the free ends are integrally connected to the reflective mirror surface. Multiple piezoelectric drive blocks are arranged on each cantilever beam. After power-on, the multiple piezoelectric drive blocks interact with each other to jointly drive the cantilever beam to bend, and the bending of the cantilever beam drives the reflective mirror surface to flip at a large angle. In addition, the MEMS micromirror includes a silicon wafer substrate, a reflective mirror surface etched on the silicon wafer substrate, and N cantilever beams, so that the MEMS micromirror has a higher degree of integration and occupies a smaller volume.

[0114] Example 2

[0115] A specific embodiment of the present invention discloses a method for manufacturing a two-dimensional biaxial piezoelectric MEMS micromirror. The manufacturing method includes two major steps:

[0116] The first major step is Fig.12 As shown, the high-performance PZT thin film is prepared through the five sub-steps of (a)(b)(c)(d)(e):

[0117] (a) A 4-inch SOI wafer C1 is selected. The SOI wafer comprises, from top to bottom, a Si device layer D1, a SiO2 buried oxide layer D2, a Si support layer D3, and a SiO2 bottom layer D4. Acetone, ethanol, and deionized water are used for ultrasonic cleaning to clean the surface of the SOI wafer C1.

[0118] (b) drying the cleaned SOI wafer C1, placing the dried SOI wafer C1 in a quartz boat, and placing the quartz boat in an oxidation furnace for dry oxygen oxidation, thereby obtaining a SiO2 protective layer C2;

[0119] (c) using physical vapor deposition (PVD) technology to sputter and deposit a metal target on the substrate to obtain a lower electrode layer C3;

[0120] (d) using PVD technology, using a Pb1.2Zr0.52Ti0.48O3 target with excess Pb, and depositing the piezoelectric material layer C4 by radio frequency magnetron sputtering;

[0121] (e) Using PVD technology, a metal target is sputtered and deposited on the substrate to obtain an upper electrode layer C5.

[0122] The second major step is Fig.13 As shown, the MEMS micromirror is prepared through the 7 sub-steps of (f)(g)(h)(i)(j)(k)(l):

[0123] (f) The upper electrode layer C5 is patterned by front lithography and ion beam etching (IBE) technology to achieve a predetermined shape of the upper electrode layer C5; the upper electrode layer C5 represents the upper metal electrode 5 of the piezoelectric material in the MEMS micromirror;

[0124] (g) hot phosphoric acid wet etching is used to pattern the piezoelectric material layer C4, and in this process, the pad of the electrode layer C3 is exposed for subsequent electrical connection; the piezoelectric material layer C4 represents the piezoelectric material 4 in the MEMS micromirror;

[0125] (h) The lower electrode layer C3 is patterned by front lithography and IBE technology; the lower electrode layer C3 represents the lower metal electrode 3 of the piezoelectric material in the MEMS micromirror;

[0126] (i) using PVD technology, sputtering depositing the reflective mirror layer on the substrate, and then patterning the reflective mirror layer by front lithography and IBE technology; the reflective mirror layer represents the reflective mirror surface 6 in the MEMS micromirror;

[0127] (j) using reactive ion etching (RIE) technology to sequentially remove the SiO2 protective layer and the Si device layer D1 until reaching the SiO2 buried oxide layer D2, thereby achieving the transfer of the MEMS micromirror structure pattern;

[0128] (k) removing the Si support layer D3 and the SiO2 bottom layer D4 by deep reactive ion etching (DRIE) technology to form a back cavity;

[0129] (l) Using RIE technology, the silicon dioxide of the SiO2 buried oxide layer D2 is etched to release the mirror structure and obtain a MEMS micromirror.

[0130] Those skilled in the art will appreciate that all or part of the processes of the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, wherein the computer-readable storage medium is a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0131] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A two-dimensional biaxial piezoelectric MEMS micromirror, characterized in that: The MEMS micromirror comprises a silicon wafer substrate, a reflective mirror surface etched on the silicon wafer substrate, and N cantilever beams, where N is 2 or 4; The N cantilever beams are symmetrically arranged around the periphery of the reflective mirror, the fixed ends of the N cantilever beams are integrally connected to the silicon wafer substrate, and the free ends are integrally connected to the reflective mirror; The fixed ends are evenly arranged on the silicon wafer substrate, and the free ends are evenly arranged on the reflective mirror surface; A piezoelectric drive block is arranged on each cantilever beam. After power is turned on, the piezoelectric drive block drives the cantilever beam to bend, and the bending of the cantilever beam drives the reflection mirror to flip.

2. The MEMS micromirror according to claim 1, characterized in that: The cantilever beam is any one of an L-shaped cantilever beam, a folded L-shaped cantilever beam, a Z-shaped cantilever beam, a folded C-shaped cantilever beam and a nested C-shaped cantilever beam.

3. The MEMS micromirror according to claim 2, characterized in that: Each piezoelectric driving block includes a piezoelectric material lower metal electrode, a piezoelectric material, and a piezoelectric material upper metal electrode, which are sequentially arranged from bottom to top.

4. The MEMS micromirror according to claim 2, characterized in that: When the cantilever beam is an L-shaped cantilever beam, N is 4, and each L-shaped cantilever beam includes a first strip segment and a second strip segment, one end of the first strip segment is a fixed end, and the other end is connected to one end of the second strip segment, and the other end of the second strip segment is a free end; The first strip segment and the second strip segment are perpendicular to each other to form an L shape; The first strip section of each L-shaped cantilever beam is arranged on the periphery of the second strip section of the previous L-shaped cantilever beam, and the second strip section of each L-shaped cantilever beam is arranged on the inner periphery of the first strip section of the next L-shaped cantilever beam, and the four L-shaped cantilever beams form a square.

5. The MEMS micromirror according to claim 2, characterized in that: When the cantilever beam is a folded L-shaped cantilever beam, N is 2, and each folded L-shaped cantilever beam includes a third strip segment, a fourth strip segment, a fifth strip segment and a sixth strip segment, one end of the third strip segment is a fixed end, and the other end is connected to one end of the fourth strip segment, the other end of the fourth strip segment is connected to one end of the fifth strip segment, the other end of the fifth strip segment is connected to one end of the sixth strip segment, and the other end of the sixth strip segment is a free end; The third strip segment and the fourth strip segment are perpendicular to each other to form an L-shape, the fifth strip segment and the sixth strip segment are perpendicular to each other to form an L-shape, and the fourth strip segment and the fifth strip segment are parallel to each other to form a folded L-shaped cantilever beam.

6. The MEMS micromirror according to claim 2, characterized in that: When the cantilever beam is a Z-shaped cantilever beam, N is 2, and each Z-shaped cantilever beam includes a first arc segment and a second arc segment, one end of the first arc segment is a fixed end, and the other end is connected to one end of the second arc segment, and the other end of the second arc segment is a free end; The central angles of the first arc segment and the second arc segment are both 180°; The first arc segment of each Z-shaped cantilever beam is arranged on the periphery of the second arc segment of another Z-shaped cantilever beam.

7. The MEMS micromirror according to claim 2, characterized in that: When the cantilever beam is a folded C-shaped cantilever beam, N is 2, each folded C-shaped cantilever beam includes a third arc segment and a fourth arc segment, one end of the third arc segment is a fixed end, and the other end is connected to one end of the fourth arc segment, and the other end of the fourth arc segment is a free end; The central angles of the third arc segment and the fourth arc segment are both 180°; The third arc segment of each folded C-shaped cantilever beam is arranged on the periphery of the fourth arc segment.

8. The MEMS micromirror according to claim 2, characterized in that: When the cantilever beam is a nested C-shaped cantilever beam, N is 2, and each nested C-shaped cantilever beam includes a fifth arc segment, a sixth arc segment, and a circular ring connecting segment, wherein two nested C-shaped cantilever beams share the same circular ring connecting segment; The annular connecting section includes two outer ends and two inner ends, and is evenly arranged on the silicon wafer substrate; The central angles of the fifth arc segment and the sixth arc segment are both 180°; One end of the fifth arc segment of each nested C-shaped cantilever beam is a fixed end, and the other end is connected to the outer end of the circular connecting segment. The inner end of the circular connecting segment is connected to one end of the sixth arc segment, and the other end of the sixth arc segment is a free end.

9. The MEMS micromirror according to claim 3, characterized in that: The piezoelectric material is any one of the following: barium titanate BT, lead zirconate titanate PZT, modified lead zirconate titanate, lead metaniobate, lead barium lithium niobate PBLN and modified lead titanate PT.

10. The MEMS micromirror according to any one of claims 1 to 10, characterized in that: The width of the cantilever beam is 30um-300um.

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