CN113376826B

CN113376826B - MEMS micro-mirror with double-sided electrode structure and preparation method thereof

Info

Publication number: CN113376826B
Application number: CN202110545663.1A
Authority: CN
Inventors: 李伟; 徐静
Original assignee: Anhui Zhongkemi Microelectronics Technology Co ltd
Current assignee: Anhui Zhongkemi Microelectronics Technology Co ltd
Priority date: 2021-05-19
Filing date: 2021-05-19
Publication date: 2023-02-17
Anticipated expiration: 2041-05-19
Also published as: CN113376826A

Abstract

The invention provides an MEMS (micro-electromechanical system) micro-mirror with a double-sided electrode structure and a preparation method thereof. The MEMS micro-mirror comprises a frame; a movable micro-mirror positioned within the frame; the elastic beam is connected with the frame and/or the movable micro-light reflector; the comb tooth structure is connected with the frame and the movable micro-light reflector to drive the movable micro-light reflector to rotate, the comb tooth structure comprises upper comb teeth and lower comb teeth, the top surfaces of the upper comb teeth are higher than the top surfaces of the lower comb teeth, and the projections of the upper comb teeth and the lower comb teeth on the horizontal plane are arranged in a staggered mode; the first upper comb tooth electrode and the second upper comb tooth electrode are connected with the upper comb teeth and correspond to each other up and down; and the first lower comb tooth electrode and the second lower comb tooth electrode are connected with the lower comb teeth. By adopting the invention, the size, the position and the like of the electrode lead slot can be flexibly selected according to design requirements, the flexibility of the device can be greatly improved, and the application range of the MEMS micro-mirror can be wider.

Description

MEMS micro-mirror with double-sided electrode structure and preparation method thereof

Technical Field

The invention belongs to the technical field of micro-electro-mechanical systems (MEMS), and particularly relates to an MEMS micro-mirror with a double-sided electrode structure and a preparation method thereof.

Background

With the development of the MEMS technology becoming mature, the application of the MEMS micro-mirror and the micro-mirror array is becoming more and more extensive, for example, the application in the fields of optical communication devices, digital display, laser scanning, etc. Electrostatic MEMS micromirrors and micromirror arrays (i.e., structures comprising a plurality of micromirrors) are receiving attention because of their advantages of compact structure, low power consumption, easy integration, etc.

At present, from the application of MEMS micromirrors and micromirror arrays, there are two kinds of electrode leading-out methods, one is leading-out from the upper surface of the device, and the other is leading-out from the lower surface of the device. An electrode of a traditional MEMS (micro-electromechanical system) micro-mirror is manufactured on the upper surface of a device and is connected with an external electrode through routing bonding; the electrodes of the conventional micromirror array are formed on the lower surface of the device and connected to the external electrodes by eutectic bonding.

The application of the electrostatic MEMS micro-mirror and the micro-mirror array is increasingly required, and higher requirements are also put on the performance and the test of the electrostatic MEMS micro-mirror and the micro-mirror array. The precise measurement of the rotation angle of the micromirror is usually realized by a high-precision optical measurement system through optical feedback to the micromirror. For the conventional micromirror array, the micromirror and the electrode are respectively located on the upper and lower surfaces of the device, and a given voltage needs to be applied to the lower surface of the device during testing, which causes great difficulty in testing the micromirror array, especially in the automated testing of the wafer level micromirror array.

Therefore, how to further improve the flexibility of the MEMS micro-mirror and micro-mirror array and improve the above-mentioned defects is a problem to be solved.

Disclosure of Invention

In view of the above disadvantages of the prior art, an object of the present invention is to provide an MEMS micro-mirror with a double-sided electrode structure and a method for manufacturing the same, which are used to solve the problems of the MEMS micro-mirror and the micro-mirror array in the prior art that the testing difficulty is high, the packaging is limited, and the application requirements are difficult to meet.

To achieve the above and other related objects, the present invention provides a MEMS micro mirror of a double-sided electrode structure, comprising:

a frame;

a movable micro mirror positioned within the frame;

the elastic beam is connected with the frame and/or the movable micro-light reflector;

the comb tooth structure is connected with the frame and the movable micro-light reflector to drive the movable micro-light reflector to rotate, the comb tooth structure comprises upper comb teeth and lower comb teeth, the top surfaces of the upper comb teeth are higher than the top surfaces of the lower comb teeth, and the projections of the upper comb teeth and the lower comb teeth on the horizontal plane are arranged in a staggered mode;

the first upper comb tooth electrode and the second upper comb tooth electrode are connected with the upper comb teeth;

and the first lower comb tooth electrode and the second lower comb tooth electrode are connected with the lower comb teeth.

Optionally, the elastic beam includes a first elastic beam and a second elastic beam, and the first elastic beam and the second elastic beam are located in the frame and connect the frame and the movable micro light reflector along a first direction.

Optionally, the frame comprises an inner frame and an outer frame located outside the inner frame, the movable micro mirror being located within the inner frame; the elastic beam further comprises a third elastic beam and a fourth elastic beam, the third elastic beam and the fourth elastic beam are located between the inner frame and the outer frame, the inner frame is connected with the outer frame along the second direction, and the second direction is perpendicular to the first direction.

Optionally, the first and second elastic beams are the same in shape and size; the third elastic beam and the fourth elastic beam are the same in shape and size; the first elastic beam, the second elastic beam, the third elastic beam and the fourth elastic beam are symmetrically distributed around the center of the movable micro light reflector.

Optionally, the MEMS micro-mirror with a double-sided electrode structure further includes a substrate, the substrate is located below the frame, the movable micro-mirror, the elastic beam, and the comb structure, and a movement space groove is provided in the substrate to provide a movement space for the movable micro-mirror and the elastic beam.

More optionally, the movement space groove is a groove with a closed bottom or a through groove which is through from top to bottom.

Optionally, the MEMS micro-mirror with double-sided electrode structure further includes a metal reflective layer, and the metal reflective layer is located on the upper surface of the movable micro-mirror.

Optionally, the MEMS micro-mirrors are multiple, and adjacent MEMS micro-mirrors are connected to each other and electrically isolated from each other.

The invention also provides a preparation method of the MEMS micro-mirror with the double-sided electrode structure, which comprises the following steps:

providing a double-device-layer substrate, wherein the double-device-layer substrate comprises a first device layer, a first insulating layer, a second device layer, a second insulating layer and a substrate layer which are sequentially stacked;

etching the first device layer and the first insulating layer to form a lower comb tooth and an upper comb tooth electrode lead slot in the first device layer, wherein the second device layer is exposed in the upper comb tooth electrode lead slot and between the lower comb teeth;

providing a substrate, forming a motion space groove and a substrate electrode lead groove which is penetrated up and down in the substrate, wherein the substrate electrode lead groove is positioned at the outer side of the motion space groove;

forming insulating layers on the surface of the etched substrate, the surface of the motion space groove and the surface of the substrate electrode lead groove;

bonding the surface of the double-device-layer substrate, which is provided with the first device layer, with the surface of the substrate, which is provided with the opening of the motion space groove, wherein the substrate electrode lead groove is opposite to the opening of the upper comb tooth electrode lead groove, and the lower comb tooth is positioned right above the motion space groove;

removing the base layer to expose the second insulating layer;

etching the second insulating layer and the second device layer to form a frame, upper comb teeth, a movable micro-light reflector, an elastic beam and a lower comb tooth electrode lead slot, wherein the movable micro-light reflector is positioned at the inner side of the frame, and the elastic beam is connected with the frame and/or the movable micro-light reflector; the lower comb electrode lead groove extends from the second device layer to a surface of the first device layer; the movable micro-light reflector and the upper comb teeth are positioned right above the movement space groove, and the projections of the upper comb teeth and the lower comb teeth on the horizontal plane are arranged in a staggered manner;

removing the second insulating layer and removing the part of the first insulating layer on the surface of the lower comb teeth;

forming a metal reflecting layer on the surface of the movable micro light reflector;

and forming a second upper comb electrode and a second lower comb electrode on the surface of the substrate electrode lead wire groove respectively, forming a first upper comb electrode on the surface of the second device layer, forming a first lower comb electrode in the lower comb electrode lead wire groove, electrically connecting the first lower comb electrode and the second lower comb electrode with lower combs, and electrically connecting the first upper comb electrode and the second upper comb electrode with upper combs.

Optionally, a lower opening size of the substrate electrode lead groove is larger than an upper opening size.

In one example, a substrate electrode lead groove is formed in the substrate, the substrate electrode lead groove and the opening of the motion space groove are located at opposite sides of the substrate, and the second upper and lower comb-tooth electrodes extend from the substrate electrode lead groove to a lower substrate surface.

In another example, a first isolation groove and a second isolation groove are formed in the substrate, the isolation grooves extend to be connected with the insulation groove and correspond to each other up and down, and the second upper comb-tooth electrode and the second lower comb-tooth electrode are located on the surface of the substrate, which is far away from the first device layer.

As described above, the MEMS micro-mirror with double-sided electrode structure and the method for manufacturing the same of the present invention have the following advantages: the MEMS micro-mirror with the double-sided electrode structure can easily build a probe and a test system above a chip during testing, so that a conventional test method can be adopted without developing or customizing special test equipment, the electrode can still be led out from the lower part during packaging, the testing and packaging flexibility of the chip can be greatly improved, and the difficult problems in the prior test technology can be effectively solved.

Drawings

Fig. 1 is a flowchart illustrating a method for fabricating a double-sided electrode structure MEMS micro-mirror according to an embodiment of the present invention.

Fig. 2 to 8 are schematic cross-sectional views of an MEMS micro-mirror with a double-sided electrode structure manufactured according to the manufacturing method of fig. 1; fig. 8 shows a schematic structure diagram of a MEMS micro-mirror with a double-sided electrode structure according to a third embodiment in an example and an enlarged schematic view of a partial structure a in fig. 11.

Fig. 9 and fig. 10 are schematic top views illustrating MEMS micromirrors with double-sided electrode structures prepared by the method of fig. 1 according to different examples.

Fig. 11 is a schematic cross-sectional view illustrating a MEMS micro-mirror with a double-sided electrode structure manufactured according to the manufacturing method of fig. 1.

Fig. 12 to 19 are schematic structural diagrams of the manufacturing method of the MEMS micro-mirror with the double-sided electrode structure according to the second embodiment of the invention in each step.

Description of the element reference numerals

11. First device layer

12. A first insulating layer

13. Second device layer

14. A second insulating layer

15. Base layer

16. Lower comb teeth

17. Upper comb electrode lead groove

18. Substrate

19. Motion space groove

20. Substrate electrode lead groove

21. Insulating layer

22. Frame structure

221. Inner frame

222. Outer frame

23. Upper comb teeth

24. Movable micro-light reflector

251. First elastic beam

252. Second elastic beam

253. Third elastic beam

254. Fourth elastic beam

26. Lower comb electrode lead slot

27. Metal reflective layer

28. Second upper comb electrode

29. Second lower comb-tooth electrode

30. First upper comb electrode

31. First lower comb electrode

32. Isolation groove

33. Insulating groove

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure of the present invention.

Please refer to fig. 1 to 19. It should be understood that the structures, ratios, sizes, etc. shown in the drawings and attached to the description are only for understanding and reading the disclosure of the present invention, and are not intended to limit the practical conditions of the present invention, so that the present invention has no technical significance, and any modifications of the structures, changes of the ratio relationships, or adjustments of the sizes, should still fall within the scope of the technical contents disclosed in the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and changes or modifications of the relative relationship may be made without substantial technical changes.

In the existing electrostatic MEMS micro-mirror array, an electrode and a micro-mirror surface are generally positioned in an upper direction and a lower direction, because the area of the micro-mirror array is large, the number of the electrodes is large, and the use of a device is influenced if the electrode is led out from the upper side, the electrode is generally positioned on the lower surface of the device. To solve such problems, the present invention proposes an improvement.

Example one

As shown in fig. 1, the present invention provides a method for manufacturing a MEMS micro-mirror with a double-sided electrode structure, comprising the following steps:

s1: as shown in step S1 of fig. 1 and fig. 2, providing a dual device layer substrate, wherein the dual device layer substrate includes a first device layer 11, a first insulating layer 12, a second device layer 13, a second insulating layer 14 and a substrate layer 15, which are stacked in sequence; the materials of the first device layer 11 and the second device layer 13 include, but are not limited to, semiconductor materials such as silicon, germanium, etc., and the first insulating layer 12 and the second insulating layer 14 include, but are not limited to, silicon oxide, silicon nitride; in a preferred example, a double-device layer SOI low-resistance silicon wafer can be used as the double-device layer substrate, so that the process flow can be simplified, and the yield and the device performance consistency can be improved;

s2: etching the first device layer 11 and the first insulating layer 12 to form a lower comb tooth 16 and an upper comb tooth 23 electrode lead slot in the first device layer 11, wherein the second device layer 13 is exposed in the upper comb tooth 23 electrode lead slot and between the lower comb teeth 16; for example, first, a photoresist is coated on the surface of the first device layer 11, a required pattern is defined through exposure and development, and then etching is performed; the lower comb teeth 16 are formed in the first device layer 11, the number of the lower comb teeth 16 is usually multiple, the multiple lower comb teeth 16 are distributed at intervals (and preferably evenly spaced), a comb tooth pair is formed with the subsequently formed upper comb teeth 23, a space corresponding to the position below the subsequently formed movable micro-light reflector 24 is reserved in the middle of the first device layer 11, and the electrode lead slot of the upper comb teeth 23 is preferably positioned outside the lower comb teeth 16; the structure obtained after this step is shown in fig. 3;

s3: providing a substrate 18, forming a motion space groove 19 and a substrate electrode lead groove 20 which is penetrated up and down in the substrate 18, wherein the substrate electrode lead groove 20 is positioned at the outer side of the motion space groove 19; the movement space groove 19 can be a groove with an opening at the upper part and a closed bottom, or a through groove which is penetrated up and down, and the depth of the movement space groove 19 determines the movement space of the elastic beam and the comb tooth structure, so that the movement space needs to be elaborately designed according to the whole structure;

s4: forming an insulating layer 21 on the surface of the etched substrate 18, the surface of the motion space groove 19 and the surface of the substrate electrode lead groove 20; for example, a silicon substrate 18 is provided, and after a desired pattern is formed by photolithography and etching, the resulting structure is oxidized to form a silicon oxide layer on the surface, and the resulting structure is shown in fig. 4; of course, in other examples, the substrate 18 and the insulating layer 21 may be made of other materials, which is not limited strictly;

s5: bonding the surface of the substrate 18 having the opening of the motion space groove 19 with the surface of the substrate 18 having the first device layer 11, wherein the substrate electrode lead groove 20 is opposite to the opening of the upper comb 23 electrode lead groove, and the lower comb 16 electrode is located right above the motion space groove 19, and the structure is shown in fig. 5;

s6: removing the base layer 15 to expose the second insulating layer 14, such as removing the base layer 15 using any one or both of etching and chemical mechanical polishing methods including but not limited to;

s7: etching the second insulating layer 14 and the second device layer 13 to form a frame 22, upper comb teeth 23, movable micro-mirrors 24, elastic beams and lower comb electrode lead grooves 26 (i.e. the frame 22, the upper comb teeth 23, the movable micro-mirrors 24 and the elastic beams are all formed in the second device layer 13, and thus the materials of the elastic beams and the second device layer are the same, such as silicon material layers), the movable micro-mirrors 24 are located inside the frame 22, and the elastic beams are connected with (directly or indirectly connected with, and then the same) the frame 22 and/or the movable micro-mirrors 24; the lower comb-tooth electrode lead groove 26 extends from the second device layer 13 to the surface of the first device layer 11 (or the lower comb-tooth electrode lead groove 26 penetrates through the second device layer 13 and the first insulating layer 12 to expose the first device layer 11); the movable micro-light reflector 24 and the upper comb teeth 23 are located right above the motion space groove 19, and the projections of the upper comb teeth 23 and the lower comb teeth 16 on the horizontal plane are arranged in a staggered manner, and the upper comb teeth 23 and the lower comb teeth 16 are both multiple to form multiple comb tooth pairs, for example, more than 3 comb tooth pairs, which is helpful for improving the sensitivity of the MEMS micro-mirror; the structure obtained after this step is shown in fig. 6;

s8: removing the second insulating layer 14 and removing the part of the first insulating layer 12 on the surface of the lower comb teeth 16 so as to ensure that the upper comb teeth 23 are not connected with the lower comb teeth 16;

s9: forming a metal reflective layer 27 on the surface of the movable micro mirror 24, for example, forming the metal reflective layer 27 by sputtering, wherein the material of the metal reflective layer 27 includes but is not limited to gold, silver, aluminum or a combination of multiple metal materials; the resulting structure of this step is shown in FIG. 7;

s10: a second upper comb-tooth electrode 28 and a second lower comb-tooth electrode 29 are respectively formed on the surface (including the bottom surface and the side wall surface) of the substrate electrode lead groove 20, a first upper comb-tooth electrode 30 is formed on the surface of the second device layer 13, a first lower comb-tooth electrode 31 is formed in the lower comb-tooth electrode lead groove 26, the first lower comb-tooth electrode 31 and the second lower comb-tooth electrode 29 are electrically connected to the lower comb-tooth 16, the first lower comb-tooth electrode 31 and the second lower comb-tooth electrode 29 can vertically correspond to each other, the first upper comb-tooth electrode 30 and the second upper comb-tooth electrode 28 are electrically connected to the upper comb-tooth 23, and the first upper comb-tooth electrode 30 and the second upper comb-tooth electrode 28 can vertically correspond to each other. The electrodes may be made of the same or different materials, and may be formed by sputtering, for example, and the second upper comb-tooth electrode 28 and the second lower comb-tooth electrode 29 may extend along the inner surface of the substrate electrode lead groove 20 to the outside to the surface of the substrate 18. The resulting structure after this step is shown in fig. 8.

In one example, the substrate electrode lead groove 20 has a lower opening dimension that is larger than an upper opening dimension, thereby facilitating metal filling to the bottom and sides during sputter forming of the second upper and lower comb-

teeth electrodes

28, 29.

In the process of etching the second insulating layer 14 and the second device layer 13, different mask patterns may be used as required to form different patterns. For example, in one example, as shown in fig. 9, the resulting MEMS micro-mirror is a uniaxial structure, i.e., the MEMS micro-mirror includes only one direction of the spring beam, and thus can rotate only in one direction. Specifically, the flexible beams include a first flexible beam 251 and a second flexible beam 252, the first flexible beam 251 and the second flexible beam 252 are located within the frame 22 along a first direction and generally connect the frame 22 with the movable micro mirror 24. The first elastic beam 251 and the second elastic beam are preferably consistent in shape and size, which is beneficial to improving the performance of the MEMS micro-mirror and enhancing the stability of the whole structure. Of course, the descriptions of "first" and "second" in this specification are for convenience of description only and are not intended to limit the specific structure.

In another example, as shown in fig. 10, the frame 22 includes an inner frame 221 and an outer frame 222 located outside the inner frame 221, and the movable micro mirror 24 is located inside the inner frame 221; the elastic beams further include a third elastic beam 253 and a fourth elastic beam 254, wherein the third elastic beam 253 and the fourth elastic beam 254 are disposed between the inner frame 221 and the outer frame 222 and generally connect the inner frame 221 and the outer frame 222 along a second direction, which is perpendicular to the first direction, i.e., the movable micromirror 24 can be driven from two directions perpendicular to each other.

In a preferred example, the first elastic beam 251 and the second elastic beam 252 have the same shape and size; the third elastic beam 253 and the fourth elastic beam 254 have the same shape and size; the first elastic beam 251, the second elastic beam 252, the third elastic beam 253, and the fourth elastic beam 254 are symmetrically distributed around the center of the movable micro mirror 24. Each elastic beam is formed simultaneously during the etching of the second insulating layer 14 and the second device layer 13 to form the frame 22 and the movable micromirror 24, etc. The spring beams and the movable micromirror 24, the frame 22 and the upper comb 23 are thus located on the same plane.

In one example, the MEMS micromirrors are multiple, and adjacent MEMS micromirrors are electrically connected and isolated from each other, as shown in fig. 11, that is, fig. 8 only corresponds to the partial structure a in fig. 11. Namely, the invention is suitable for forming the MEMS micro-mirror array at the wafer level.

It should be specially noted that, the sequence numbers of the above steps are only used for illustrating the process of the present invention in more detail, and are not used for limiting the sequence. In fact, the order of the steps can be adjusted and/or the corresponding steps can be combined as desired, for example, the process of etching the substrate 18 to form the motion space groove 19 and the substrate electrode lead groove 20 can be performed simultaneously with the process of etching the dual device layer substrate to form the lower comb 16 and the upper comb 23 electrode lead grooves on different devices. Specifically, in a certain step, for example, in the process of forming the movement space groove 19 and the substrate electrode lead groove 20 penetrating up and down in the substrate 18, the movement space groove 19 and the substrate electrode lead groove 20 may be completed by the same etching process or different etching processes (from the viewpoint of cost, it is preferable to form them by using the same mask in the same etching process), for example, the first upper comb-teeth electrode 30, the first lower comb-teeth electrode 31, and the metal reflective layer 27 may be completed simultaneously in the same process, which is not strictly limited. Importantly, by adopting the invention, the size, the position and the like of the electrode lead groove can be flexibly selected according to design requirements, the flexibility of the device can be greatly improved, and the application range of the MEMS micro-mirror can be wider. The MEMS micro-mirror with the double-sided electrode structure can easily build a probe and a test system above a chip during testing, so that a conventional test method can be adopted without developing or customizing special test equipment, the electrode can still be led out from the lower part during packaging, the testing and packaging flexibility of the chip can be greatly improved, and the difficult problems in the prior test technology can be effectively solved.

Example two

As shown in fig. 12 to 19, the present invention further provides another method for manufacturing a MEMS micro-mirror with a double-sided electrode structure, the method of this embodiment is different from the first embodiment mainly in that a substrate electrode lead groove penetrating through a substrate is formed in the substrate, and a second upper comb-tooth electrode and a second lower comb-tooth electrode extend from the substrate electrode lead groove to a lower surface of the substrate; in this embodiment, the substrate electrode lead groove is not formed, and the second upper comb-tooth electrode and the second lower comb-tooth electrode are directly formed on the surface of the substrate away from the first device layer, and a plurality of isolation grooves penetrating through the substrate are correspondingly formed in the substrate (it can be considered that the isolation grooves and the insulation grooves which correspond to each other up and down and are connected with each other jointly penetrate through the substrate) to perform an electrical insulation function.

Specifically, the preparation method of the invention comprises the following steps:

providing a substrate 18, forming a movement space groove 19, an insulation groove 33 and an isolation groove 32 on two opposite sides of the substrate 18, wherein the movement space groove 19, the insulation groove 33 and the isolation groove 32 all extend along the longitudinal direction of the substrate 18; the step may specifically include forming a plurality of isolation trenches 32 in the substrate 18 by photolithography etching, the resulting structure is as shown in fig. 12, then filling insulating materials, including but not limited to silicon dioxide, in the isolation trenches, the resulting structure is as shown in fig. 13, then forming a motion space trench 19 and an insulation trench 33 in the substrate 18, where openings of the motion space trench 19 and the isolation trench 32 are located on two opposite sides of the substrate 18, and the motion space trench 19 and the insulation trench 33 extend to the surface of the isolation trench 32, or the motion space trench 19 and/or the insulation trench 33 are communicated with the isolation trench 32, and the resulting structure is as shown in fig. 14;

providing a dual-device-layer substrate, wherein the dual-device-layer substrate includes a first device layer 11, a first insulating layer 12, a second device layer 13, a second insulating layer 14, and a substrate layer 15, which are stacked in sequence, etching the first device layer 11 and the first insulating layer 12 to form a plurality of lower comb teeth 16 in the first device layer 11, exposing the second device layer 13 between the lower comb teeth 16 (i.e., the first insulating layer 12 between the lower comb teeth 16 is etched away), and forming grooves corresponding to subsequent movable micro-mirrors between the lower comb teeth 16, the grooves penetrating through the first device layer and the first insulating layer, and the resulting structure is shown in fig. 15;

bonding the side of the two-device layer substrate having the first device layer 11 to the side of the substrate 18 having the opening of the motion space groove 19, wherein the lower comb 16 is located directly above the motion space groove 19, the resulting structure is shown in fig. 16;

removing the base layer 15 and the second insulating layer 14 to expose the second device layer 13;

etching the second device layer 13 and the first insulating layer 12 to form a frame 22, upper comb teeth 23, a movable micro-light reflector 24, an elastic beam, an upper comb tooth electrode lead slot 17 and a lower comb tooth electrode lead slot 26, wherein the movable micro-light reflector 24 is positioned on the inner side of the frame 22, and the elastic beam is connected with the frame 22 and/or the movable micro-light reflector 24; the upper comb-tooth electrode lead groove 17 and the lower comb-tooth electrode lead groove 26 both penetrate through the second device layer 13 and the first insulating layer 12 until extending to the surface of the first device layer 11; the movable micro-light reflector 24 and the upper comb teeth 23 are positioned right above the movement space groove 19, and the projections of the upper comb teeth 23 and the lower comb teeth 16 on the horizontal plane are arranged in a staggered manner, and the structure obtained in this step is shown in fig. 17;

removing the first insulating layer 12 on the surface of the lower comb teeth 16;

forming a metal reflective layer 27, a first upper comb-tooth electrode 30, a second upper comb-tooth electrode 28, a first lower comb-tooth electrode 31, and a second lower comb-tooth electrode 29, wherein the metal reflective layer 27 is located on the surface of the movable micro-mirror 24; the first upper comb-tooth electrode 30 extends from the upper comb-tooth electrode lead groove 17 to the surface of the first device layer, the first lower comb-tooth electrode 31 is located in the lower comb-tooth electrode lead groove 26, the second upper comb-tooth electrode 28 and the second lower comb-tooth electrode 29 are located on the surface of the substrate 18 away from the first device layer 11, the first lower comb-tooth electrode 31 and the second lower comb-tooth electrode 29 are both electrically connected with the lower comb-tooth 16, the first upper comb-tooth electrode 30 and the second upper comb-tooth electrode 28 are both electrically connected with the upper comb-tooth 23, and the structure obtained in this step is shown in fig. 18.

In this embodiment, compared to the first embodiment, except that the substrate electrode lead groove is not formed, the second upper comb-tooth electrode and the second lower comb-tooth electrode are directly formed on the surface of the substrate away from the first device layer, and a plurality of isolation grooves penetrating through the substrate are correspondingly formed in the substrate to perform an electrical insulation function, other parts, including the material of each structure, and the processing processes and the like of each structure layer are substantially the same. The top view structure of the MEMS micro-mirror with double-sided electrode formed finally in this embodiment is also substantially the same as that in the first embodiment, and specifically, refer to fig. 10.

In addition, the manufacturing method of the present embodiment can also be used to manufacture a single or multiple MEMS micro-mirrors, and when there are multiple MEMS micro-mirrors, the multiple MEMS micro-mirrors may be sequentially arranged in an array, which may specifically refer to fig. 19, that is, fig. 18 is an enlarged schematic view of the area a of fig. 19.

EXAMPLE III

The invention provides a MEMS micro-mirror with a double-sided electrode structure, which can be prepared based on the preparation method in any one of the first embodiment or the second embodiment, so the description of the MEMS micro-mirror is fully applicable to the MEMS micro-mirror. Of course, the invention can also be prepared on the basis of other methods, which are not restricted to these.

Specifically, as shown in fig. 8 to fig. 11 (fig. 8 can be regarded as a schematic partial cross-sectional structure of fig. 9 and 10), the MEMS micro-mirror with a double-sided electrode structure provided by the present invention includes:

a frame 22;

a movable micro mirror 24 positioned within the frame 22;

an elastic beam connected to the frame 22 and/or the movable micro mirror 24;

the comb tooth structure is connected with the frame 22 and the movable micro-light reflector 24 to drive the movable micro-light reflector 24 to rotate, the comb tooth structure comprises upper comb teeth 23 and lower comb teeth 16, the top surfaces of the upper comb teeth 23 are higher than the top surfaces of the lower comb teeth 16, the projections of the upper comb teeth 23 and the lower comb teeth 16 on the horizontal plane are arranged in a staggered mode, and the upper comb teeth 23 and the lower comb teeth 16 are preferably multiple to form multiple electrostatic comb tooth pairs;

first and second upper comb-

teeth electrodes

30 and 28 connected to the upper comb-teeth 23 and corresponding to each other in the vertical direction, for example, the first upper comb-teeth electrode 30 is formed on the upper surface of the frame 22 and the second upper comb-teeth electrode 28 is located below the frame 22;

the first lower comb-tooth electrode 31 and the second lower comb-tooth electrode 29 are connected to the lower comb-tooth 16 and vertically correspond to each other, and for example, as can be seen from the first embodiment, the first lower comb-tooth electrode 31 is formed on the surface of the first device layer 11 and the second lower comb-tooth electrode 29 is located below the first device layer 11.

By way of example, the frame 22, spring beam, movable micromirror 24, and comb structure may be made of semiconductor materials including, but not limited to, silicon, germanium, and the like.

The MEMS micro-mirror adopts a double-sided electrode structure design, and can greatly improve the test and packaging flexibility of a chip.

In one example, as shown in fig. 9, the elastic beams include a first elastic beam 251 and a second elastic beam 252, and the first elastic beam 251 and the second elastic beam 252 are located in the frame 22 and connect the frame 22 and the movable micro light reflector 24 along a first direction. This arrangement is relatively simple, but the movable micromirror 24 can rotate only in one direction. To improve the stability of the overall structure and the device performance, the first elastic beam 251 and the second elastic beam 252 are preferably identical in size and shape.

In another example, as shown in fig. 10, the frame 22 includes an inner frame 221 and an outer frame 222 located outside the inner frame 221, and the movable micro mirror 24 is located inside the inner frame 221; the elastic beams further include third and fourth

elastic beams

253 and 254, and the third and fourth

elastic beams

253 and 254 are located between the inner frame 221 and the outer frame 222 and connect the inner frame 221 and the outer frame 222 along a second direction perpendicular to the first direction. In this embodiment, the movable micromirror 24 is driven to rotate from two mutually perpendicular directions.

To further improve the device performance, as an example, the first elastic beam 251 and the second elastic beam 252 have the same shape and size; the third elastic beam 253 and the fourth elastic beam 254 have the same shape and size; the first elastic beam 251, the second elastic beam 252, the third elastic beam 253, and the fourth elastic beam 254 are symmetrically distributed around the center of the movable micro mirror 24.

In one example, the MEMS micro-mirror with double-sided electrode structure further includes a substrate 18, the substrate 18 is located under the frame 22, the movable micro-mirror 24, the elastic beam and the comb structure, and a movement space groove 19 is provided in the substrate 18 to provide a movement space for the movable micro-mirror 24 and the elastic beam. The movement space groove 19 may be a groove with a closed bottom or a through groove passing through the groove from top to bottom.

In one example, as shown in fig. 8, a substrate electrode lead groove 20 (a structure prepared based on the method of the first embodiment) is formed in the substrate 18, the substrate electrode lead groove 20 and the opening of the movement space groove 19 are located at opposite sides of the substrate 18, and the second upper comb-tooth electrode 28 and the second lower comb-tooth electrode 29 extend from the substrate electrode lead groove 20 to the lower surface of the substrate.

In another example, as shown in fig. 18, a plurality of isolation trenches 32 and isolation trenches 33 (the structure is prepared based on the method of the second embodiment) are formed in the substrate 18, the openings of the isolation trenches 32 and the motion space trenches 19 are located at opposite sides of the substrate 18, the isolation trenches 32 extend to be connected to the motion space trenches 19 or the isolation trenches 33, and the second upper and

lower comb electrodes

28 and 29 are located at a surface of the substrate 18 facing away from the first device layer 11 (i.e., a surface facing away from the motion space trenches 19).

As an example, the MEMS micro mirror with double-sided electrode structure further includes a metal reflective layer 27, where the metal reflective layer 27 is located on the upper surface of the movable micro mirror 24 to improve the light reflection performance of the movable micro mirror 24 and improve the device sensitivity. The material of the metal reflective layer 27 includes, but is not limited to, a single metal or an alloy material such as gold, silver, copper, aluminum, etc.

In one example, as shown in fig. 11, there are a plurality of MEMS micromirrors, and adjacent MEMS micromirrors are connected to each other and electrically isolated from each other, i.e., fig. 8 is an enlarged schematic view of only a partial structure a in fig. 11. The MEMS micromirrors can be fabricated and packaged simultaneously by wafer-level fabrication process, which can greatly improve production efficiency. Due to the adoption of the design of the double-sided electrode structure, the electrode can be led out from the upper part during testing, and the packaging and testing flexibility of the chip is greatly improved.

For a more detailed description, please refer to the contents of the first or second embodiment, which are not repeated herein for brevity.

In summary, the present invention provides an MEMS micro-mirror with a double-sided electrode structure and a method for fabricating the same. The MEMS micro-mirror comprises a frame; a movable micro mirror positioned within the frame; the elastic beam is connected with the frame and/or the movable micro-light reflector; the comb tooth structure is connected with the frame and the movable micro-light reflector to drive the movable micro-light reflector to rotate, the comb tooth structure comprises upper comb teeth and lower comb teeth, the top surfaces of the upper comb teeth are higher than the top surfaces of the lower comb teeth, and the projections of the upper comb teeth and the lower comb teeth on the horizontal plane are arranged in a staggered mode; the first upper comb tooth electrode and the second upper comb tooth electrode are connected with the upper comb teeth and correspond to each other up and down; and the first lower comb tooth electrode and the second lower comb tooth electrode are connected with the lower comb teeth and correspond to each other up and down. By adopting the invention, the size, the position and the like of the electrode lead slot can be flexibly selected according to design requirements, the flexibility of the device can be greatly improved, and the application range of the MEMS micro-mirror can be wider. The MEMS micro-mirror with the double-sided electrode structure can easily build a probe and a test system above a chip during testing, so that a conventional test method can be adopted without developing or customizing special test equipment, the electrode can still be led out from the lower part during packaging, the testing and packaging flexibility of the chip can be greatly improved, and the difficult problems in the prior test technology can be effectively solved. The invention has outstanding advantages when being used for preparing the MEMS micro-mirror array. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Those skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A MEMS micro-mirror with a double-sided electrode structure, comprising:

a frame;

a movable micro mirror positioned within the frame;

the first lower comb tooth electrode and the second lower comb tooth electrode are connected with the lower comb teeth;

the lower comb teeth are formed in a first device layer, the frame, the movable micro-light reflector, the elastic beam and the upper comb teeth are formed in a second device layer, the second device layer is stacked above the first device layer, the first upper comb teeth electrode and the second upper comb teeth electrode correspond to each other up and down, and the first lower comb teeth electrode and the second lower comb teeth electrode correspond to each other up and down.

2. The MEMS micro-mirror with double-sided electrode structure of claim 1, wherein the elastic beam comprises a first elastic beam and a second elastic beam, the first elastic beam and the second elastic beam are located inside the frame and connect the frame and the movable micro-mirror along a first direction.

3. The MEMS micromirror of claim 2, wherein the frame comprises an inner frame and an outer frame located at the periphery of the inner frame, the movable micromirror being located within the inner frame; the elastic beam further comprises a third elastic beam and a fourth elastic beam, the third elastic beam and the fourth elastic beam are located between the inner frame and the outer frame, the inner frame is connected with the outer frame along the second direction, and the second direction is perpendicular to the first direction.

4. The double-sided electrode structure MEMS micro-mirror of claim 3, wherein the first and second elastic beams are the same shape and size; the third elastic beam and the fourth elastic beam are the same in shape and size; the first elastic beam, the second elastic beam, the third elastic beam and the fourth elastic beam are symmetrically distributed around the center of the movable micro light reflector.

5. The MEMS micro-mirror with double-sided electrode structure as claimed in claim 1, further comprising a substrate under the frame, the movable micro-mirror, the elastic beam and the comb structure, wherein a movement space slot is formed in the substrate to provide a movement space for the movable micro-mirror and the elastic beam; the motion space groove is a groove with a closed bottom or a through groove which is communicated up and down.

6. The MEMS micro-mirror of double-sided electrode structure of claim 5, wherein a substrate electrode lead groove is formed in the substrate, the substrate electrode lead groove and the opening of the motion space groove are located at opposite sides of the substrate, and the second upper comb-tooth electrode and the second lower comb-tooth electrode extend from the substrate electrode lead groove to a lower surface of the substrate; or a plurality of isolation grooves are formed in the substrate, the isolation grooves extend to be connected with the insulation grooves and are corresponding to the insulation grooves up and down, and the second upper comb-tooth electrode and the second lower comb-tooth electrode are located on the surface of the substrate departing from the first device layer.

7. The double-sided electrode structure MEMS micro-mirror of claim 1, further comprising a metal reflective layer on an upper surface of the movable micro-mirror.

8. The double-sided electrode structure MEMS micro-mirror according to any one of claims 1 to 7, wherein the MEMS micro-mirror is plural, and adjacent MEMS micro-mirrors are connected to each other and electrically isolated from each other.

9. A preparation method of an MEMS micro-mirror with a double-sided electrode structure is characterized by comprising the following steps:

providing a substrate, forming a motion space groove and a substrate electrode lead groove which is penetrated through from top to bottom in the substrate, wherein the substrate electrode lead groove is positioned at the outer side of the motion space groove;

bonding one surface of the double-device-layer substrate, which is provided with the first device layer, with one surface of the substrate, which is provided with the opening of the motion space groove, wherein the substrate electrode lead groove is opposite to the opening of the upper comb electrode lead groove, and the lower comb is positioned right above the motion space groove;

removing the base layer to expose the second insulating layer;

forming a metal reflecting layer on the surface of the movable micro reflector;

and a second upper comb electrode and a second lower comb electrode are respectively formed on the surface of the substrate electrode lead slot, a first upper comb electrode is formed on the surface of the second device layer, a first lower comb electrode is formed in the lower comb electrode lead slot, the first lower comb electrode and the second lower comb electrode are both electrically connected with lower combs, and the first upper comb electrode and the second upper comb electrode are both electrically connected with upper combs.

10. A preparation method of an MEMS micro-mirror with a double-sided electrode structure is characterized by comprising the following steps:

providing a substrate, and forming a motion space groove, an insulation groove and an isolation groove on two opposite sides of the substrate, wherein the motion space groove and the isolation groove extend along the longitudinal direction of the substrate;

providing a double-device-layer substrate, wherein the double-device-layer substrate comprises a first device layer, a first insulating layer, a second device layer, a second insulating layer and a substrate layer which are sequentially stacked, etching is carried out on the first device layer and the first insulating layer so as to form a plurality of lower comb teeth in the first device layer, and the second device layer is exposed among the plurality of lower comb teeth;

bonding the side of the dual device layer base having the first device layer to the side of the substrate having the motion space slot opening, wherein the lower comb tooth is located directly above the motion space slot;

removing the base layer and the second insulating layer to expose the second device layer;

etching the second device layer and the first insulating layer to form a frame, upper comb teeth, a movable micro-light reflector, an elastic beam, an upper comb tooth electrode lead slot and a lower comb tooth electrode lead slot, wherein the movable micro-light reflector is positioned at the inner side of the frame, and the elastic beam is connected with the frame and/or the movable micro-light reflector; the upper comb-tooth electrode lead slot and the lower comb-tooth electrode lead slot penetrate through the second device layer and the first insulating layer until the upper comb-tooth electrode lead slot and the lower comb-tooth electrode lead slot extend to the surface of the first device layer; the movable micro-light reflector and the upper comb teeth are positioned right above the movement space groove, and the projections of the upper comb teeth and the lower comb teeth on the horizontal plane are arranged in a staggered manner;

removing the first insulating layer on the surface of the lower comb teeth;

forming a metal reflecting layer, a first upper comb tooth electrode, a second upper comb tooth electrode, a first lower comb tooth electrode and a second lower comb tooth electrode, wherein the metal reflecting layer is positioned on the surface of the movable micro-light reflector; the first upper comb electrode extends to the surface of a first device layer from the upper comb electrode lead groove, the first lower comb electrode is located in the lower comb electrode lead groove, the second upper comb electrode and the second lower comb electrode are located on the surface, deviating from the first device layer, of the substrate, the first lower comb electrode and the second lower comb electrode are electrically connected with the lower comb, and the first upper comb electrode and the second upper comb electrode are electrically connected with the upper comb.