CN113031249A

CN113031249A - Micro-mirror control device based on photoelectric feedback

Info

Publication number: CN113031249A
Application number: CN201911252592.5A
Authority: CN
Inventors: 马宏
Original assignee: Juexin Electronics Wuxi Co ltd
Current assignee: Juexin Electronics Wuxi Co ltd
Priority date: 2019-12-09
Filing date: 2019-12-09
Publication date: 2021-06-25
Anticipated expiration: 2039-12-09
Also published as: CN113031249B

Abstract

The invention discloses a micro-mirror control device based on photoelectric feedback, which comprises a micro-mirror chip, a photoelectric feedback module, a switching structure and a control module, wherein the micro-mirror chip is connected with the photoelectric feedback module; the micro-mirror chip comprises a movable mirror surface and a back cavity; the photoelectric feedback module comprises a light source and at least one photoelectric device; the movable mirror surface is positioned at the top of the back cavity, the bottom of the back cavity is connected with the switching structure, and the light source and the at least one photoelectric device are positioned at the bottom of the back cavity and are arranged on the switching structure; the movable mirror surface can reflect light beams emitted by the light source to the bottom of the back cavity to form light spots, at least one photoelectric device is used for converting phase information deflected by the movable mirror surface into corresponding photoelectric information in real time according to the light spots, and the control module is used for controlling the micro-mirror chip and/or the photoelectric feedback module according to the photoelectric information. The invention has wide application range, stable performance, high sensitivity and high integration level, and is suitable for the chip-level and system-level packaging of various MEMS micro-mirror devices.

Description

Micro-mirror control device based on photoelectric feedback

Technical Field

The invention relates to the technical field of photoelectricity, in particular to a micro mirror control device based on photoelectric feedback.

Background

Since the first release of scanning silicon mirrors in 1980, Micro Electro Mechanical Systems (MEMS) have been widely used in the field of optical scanning, and a large number of technologies and products have been developed. The field of optical scanning has become an important direction of MEMS research. With the development of technology, in the past decade, the application of micro-projection technology and numerous medical imaging technologies has become the main direction for the development of current MEMS optical scanning devices, especially laser scanning devices.

MEMS micromirror devices are highly susceptible to external environmental interference due to their small size and structural complexity. To ensure stable operation of the MEMS micro-mirror device, the MEMS micro-mirror chip usually needs special package protection and feedback control. The currently used feedback control methods are mainly divided into two types, one is a piezoresistive feedback system based on a piezoresistive sensor, and the other is a capacitance feedback system based on capacitance change. However, the above methods all have certain limitations. For the piezoresistive feedback system, because the performance of the piezoresistive sensor is greatly influenced by temperature change, the piezoresistive feedback system is only suitable for application with small temperature change and can hardly be used in severe working environments such as vehicle-mounted environment. This drawback of piezoresistive sensors also greatly limits the performance and application of MEMS devices based on piezoresistive feedback systems. The capacitive feedback system is based on a structure that generates capacitance change along with the movement of the MEMS movable structure, and the common structure includes a comb-tooth pair structure or a plate capacitor structure. Due to this dependency on a special structure, the capacitive feedback system is generally only used for MEMS micro-mirror devices based on electrostatic actuation, but not for other MEMS micro-mirror devices, such as electromagnetically actuated micro-mirrors or electro-thermally actuated micro-mirrors.

In addition to piezoresistive and capacitive feedback systems, the use of an electro-optical feedback system to control a MEMS micro-mirror device is also an effective way. However, due to low integration degree, related components are complex, the method for controlling the MEMS micro-mirror device by utilizing the photoelectric feedback system is still basically in the academic research stage at present, the overall size of the built system is generally 5-6 mm, and the method is almost not suitable for commercial application.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a micro-mirror control device based on photoelectric feedback, which comprises a micro-mirror chip, a photoelectric feedback module, a switching structure and a control module; the micro-mirror chip comprises a movable mirror surface and a back cavity; the optoelectronic feedback module comprises a light source and at least one optoelectronic device;

the movable mirror surface is positioned at the top of the back cavity, the bottom of the back cavity is connected with the adapter structure, the light source and the at least one photoelectric device are positioned at the bottom of the back cavity, and the light source and the at least one photoelectric device are both arranged on the adapter structure;

the movable mirror surface can reflect light beams emitted by the light source to the bottom of the back cavity to form light spots, the at least one photoelectric device is used for converting phase information deflected by the movable mirror surface into corresponding photoelectric information in real time according to the light spots, and the control module is used for controlling the micro-mirror chip and/or the photoelectric feedback module according to the photoelectric information.

Further, the adapter structure comprises a first adapter plate and a second adapter plate;

the first adapter plate is connected with the bottom of the back cavity, and the second adapter plate is arranged below the first adapter plate;

the first interposer board is connected to the second interposer board by an electrical interconnection via structure that extends through the first interposer board;

the light source is arranged on the first adapter plate or the second adapter plate, and the at least one photoelectric device is arranged on the first adapter plate and/or the second adapter plate.

Furthermore, the first adapter plate is provided with a plurality of light through holes;

the light through hole corresponds to the light source and/or the photoelectric device arranged on the second adapter plate up and down so as to control the light to enter and exit. Specifically, the light-passing hole structure also has a light filtering function; the light through hole structure is arranged above the photoelectric device and used for eliminating the influence of stray light on feedback precision while controlling the light input quantity.

Further, the first adapter plate is formed with a cavity structure and a protrusion structure;

the protruding structure is arranged in the central area of the first adapter plate, a perforated structure is arranged on the protruding structure, and the perforated structure corresponds to the light source arranged on the second adapter plate up and down;

the protruding structure is an island structure which is not connected with other structures of the first adapter plate, or the protruding structure is an integral structure which is connected with other structures of the first adapter plate.

Furthermore, the first adapter plate is made of monocrystalline silicon or glass or PCB, the second adapter plate is made of monocrystalline silicon or glass or ceramic or PCB and the like, and the first adapter plate and the second adapter plate are made of the same or different materials. When the switching structure is made of glass, the light source and the photoelectric device are arranged inside or outside the micro-mirror control device.

Further, the control module includes an ASIC chip;

the ASIC chip is arranged outside the micro-mirror control device, or the ASIC chip is welded in the switching structure, or the ASIC chip is directly integrated in the switching structure through a semiconductor process;

the ASIC chip is connected with the micromirror chip and the photoelectric feedback module through an electrical interconnection structure.

Further, the electrical interconnection structure comprises a Through Silicon Via (TSV) structure, a first bonding pad, a second bonding pad and a metal wire layer; the silicon through hole structure penetrates through the micro-mirror chip, the top end of the silicon through hole structure is connected with the first bonding pad, the bottom of the silicon through hole structure is connected with the second bonding pad, and the second bonding pad is connected with a bonding pad arranged on the switching structure;

or, the electrical interconnection structure comprises a third pad and a lead, one end of the lead is connected with the third pad, and the other end of the lead is connected with a pad arranged on the adapting structure.

Further, the micro-mirror chip comprises at least one device layer, at least one buried oxide layer and a substrate layer,

the movable mirror surface is arranged on the device layer;

the back cavity is formed on the buried oxide layer and the substrate layer, and the side wall of the back cavity is vertical to or inclined with the device layer;

the substrate layer is connected with the switching structure;

the device layer, the oxygen buried layer and the substrate layer are sequentially stacked.

Further, the light source is arranged on the adapting structure in a conductive silver adhesive bonding or welding manner;

the photoelectric device is arranged on the switching structure in a conductive silver adhesive bonding or solder welding mode, or the photoelectric device is directly integrated on the switching structure through a semiconductor process.

Further, the movable mirror surface (11) is a movable mirror surface of a one-dimensional micro-mirror or a two-dimensional micro-mirror, and the photoelectric device comprises any one of a single-point type photoelectric detector, a two-dimensional photoelectric position detector and a one-dimensional photoelectric position detector.

The implementation of the invention has the following beneficial effects:

1. compared with the prior art of controlling the micromirror device by using a feedback system, the micromirror control device based on photoelectric feedback provided by the embodiment of the invention has the characteristics of wide application range, stable performance, high sensitivity, high integration level and the like, and is suitable for packaging various MEMS micromirror devices at chip level and system level.

2. The implementation mode of the micro-mirror control device based on photoelectric feedback provided by the embodiment of the invention is simple, and the related processes, technologies, components and the like are all the prior art, so that the micro-mirror control device has the advantages of convenience in production, high process stability, low cost and the like.

3. The device provided by the embodiment of the invention is particularly suitable for MEMS products with high integration level and miniaturization degree, can be applied to millimeter-scale modules, and is further integrated in various consumer electronic products and other product equipment applied to extreme working environments.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic structural diagram of a micromirror control device based on electro-optical feedback according to an embodiment of the invention;

FIG. 2 is a partial top view of a micromirror control device based on electro-optical feedback according to an embodiment of the invention;

FIG. 3 is a partial top view of a micromirror control device based on electro-optical feedback according to an embodiment of the invention;

FIG. 4 is a partial top view of a micromirror control device based on electro-optical feedback according to an embodiment of the invention;

FIG. 5 is a partial top view of a micromirror control device based on electro-optical feedback according to an embodiment of the invention;

FIG. 6 is a partial top view of a micromirror control device based on electro-optical feedback according to an embodiment of the invention, wherein the electro-optical device employs a two-dimensional electro-optical position detector;

FIG. 7 is a partial top view of a micromirror control device based on electro-optical feedback according to an embodiment of the invention, wherein a plurality of electro-optical devices are employed as the photo-electric position detectors;

FIG. 8 is a schematic structural diagram of a micromirror control device based on electro-optical feedback according to an embodiment of the invention;

FIG. 9 is a schematic structural diagram of a micromirror control device based on electro-optical feedback according to an embodiment of the invention;

FIG. 10 is a schematic structural diagram of a micromirror control device based on electro-optical feedback according to an embodiment of the invention;

FIG. 11 is a schematic structural diagram of a micromirror control device based on electro-optical feedback according to an embodiment of the invention;

FIG. 12 is a schematic top view of the adapter plate of FIG. 11 in the context of the back cavity;

fig. 13 is a schematic structural diagram of a micromirror control device based on optoelectronic feedback according to an embodiment of the present invention, wherein a control module is connected to a micromirror chip through a through-silicon via structure;

fig. 14 is a schematic structural diagram of a micromirror control device based on optoelectronic feedback according to an embodiment of the present invention, wherein the control module and the micromirror chip are connected by wire bonding.

The micro-mirror comprises a micro-mirror chip 1, a movable mirror surface 11, a back cavity 12, a device layer 13, an oxygen buried layer 14, a substrate layer 15 and a fixed frame 16;

21-light source, 22-photovoltaic device;

31-a first adapter plate, 32-a second adapter plate; 311-electrical interconnection perforation structure, 312-light through hole, 313-convex structure, 314-bonding pad arranged on the switching structure, 315-metal layer on the first switching plate, 316-insulating medium layer on the surface of the first switching plate; 3131-a perforated structure;

41-an ASIC chip;

51-through silicon via structure, 52-first pad, 53-second pad, 54-third pad, 55-lead;

6-bonding material layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout.

Examples

Fig. 1 is a schematic structural diagram of a micromirror control device based on optoelectronic feedback according to an embodiment of the present invention, and referring to fig. 1, the micromirror control device based on optoelectronic feedback according to the embodiment includes a micromirror chip 1, an optoelectronic feedback module, a switching structure and a control module.

The micromirror chip 1 is fabricated by processing an SOI wafer through a semiconductor process. The micromirror chip 1 comprises one or more layers of single crystal silicon device 13, one or more layers of silicon dioxide buried oxide 14, and a single crystal silicon substrate layer 15. The device layer 13, the buried oxide layer 14 and the substrate layer 15 are stacked in sequence.

In detail, the thickness of the monocrystalline silicon device layer 13 is between 10 and 100 μm, the thickness of the silicon dioxide buried layer is between 0.1 and 3 μm, and the thickness of the monocrystalline silicon substrate layer 15 is between 100 and 800 μm.

The device layer 13 is provided with the movable mirror 11 and the fixed frame 16 through semiconductor process processing. The movable structure of the micromirror chip 1 includes a torsion axis and the like in addition to the movable mirror surface 11. The bottom of the movable mirror 11 is provided with a back cavity 12.

With continued reference to fig. 1, the back cavity 12 is formed by etching the substrate layer 15 and the buried oxide layer 14. In some embodiments, the back cavity 12 is formed with sidewalls that are sloped with respect to the device layer 13 using an anisotropic wet etch process of single crystal silicon. In some embodiments, a via etching process may be selected to reduce the lateral size of the chip by using the characteristic of the anisotropic wet etching process of single crystal silicon to form a back cavity 12 with a rectangular shape in the horizontal direction on the wafer surface and a sidewall inclined with respect to the device layer 13. In some embodiments, a deep silicon etch process may also be used to form the back cavity 12 with sidewalls that are vertical with respect to the device layer 13.

The bottom of the back cavity 12 is connected to an adapter structure comprising a first adapter plate 31 and a second adapter plate 32. The first adapter plate 31 is connected with the bottom of the back cavity 12, the second adapter plate 32 is arranged below the first adapter plate 31, and the first adapter plate 31 is connected with the second adapter plate 32 in a soldering mode through the electric interconnection perforated structure 311 so as to achieve electric interconnection with the outside. The electrical interconnection perforation structure 311 penetrates the first transfer plate 31.

Specifically, the electrical interconnect via structure 311 includes a via structure, a metal layer 315 disposed at a top end of the via structure, and a metal layer disposed at a bottom end of the via structure. Optionally, the metal layer comprises a pad; optionally, the metal layer 315 includes a pad and a metal wire layer; the bonding pad is used for welding the chip and the integrated light source 21 and the photoelectric device 22, and plays a role in wetting; the metal wire layer is used to realize electrical interconnection on the first interposer board 31.

Specifically, the Through hole structure includes, but is not limited to, a TSV and a Through Glass Via (TGV), a material of the Through hole structure depends on a material of the first interposer 31, and in practical applications, the material of the Through hole structure may be selected according to the material of the first interposer 31. For example, in some embodiments, the first interposer 31 is made of single crystal silicon, and the through hole structure thereof is TSV; in some embodiments, the first transfer plate 31 is made of glass, and the through hole structure thereof is TGV.

Specifically, the material of the first interposer 31 may be monocrystalline silicon, glass, or PCB, the material of the second interposer 32 may be monocrystalline silicon, glass, ceramic, or PCB, and the first interposer 31 and the second interposer 32 may be made of the same material or different materials.

With continued reference to fig. 1, depending on the materials used for the first interposer 31 and the second interposer 32, in some embodiments, an insulating dielectric layer 316 is further disposed on the surface of each interposer.

In some embodiments, the substrate layer 15 of the micromirror chip 1 is bonded integrally with the first transfer plate 31. It should be noted that the bonding process used in the actual operation depends on the material of the first transfer plate 31, including but not limited to anodic bonding, eutectic bonding, and the like. The first transfer plate 31 constitutes a hermetic package of the micromirror device together with a glass sealing window (not shown) bonded on top of the micromirror chip 1.

With continued reference to fig. 1, the optoelectronic feedback module includes a light source 21 and at least one optoelectronic device 22(PD), the light source 21 and the at least one optoelectronic device 22 are located at the bottom of the back cavity 12, and the light source 21 and the at least one optoelectronic device 22 are both disposed on the adapting structure. The light source 21 and the photoelectric device 22 are previously disposed on the first transfer plate 31 before bonding. The first transfer plate 31 is provided with a metal layer 315.

Optionally, the light source 21 is an LED, LD or VCSEL.

In detail, the metal layer 315 includes a metal wire structure, a pad structure, and the like, and the pad may be a metal pad, a metal oxide pad, and the like.

In some embodiments, the light source 21 and the photovoltaic device 22 are disposed on the first adapter plate 31 by means of conductive silver paste bonding or the like.

In some embodiments, the optoelectronic device 22 may be integrated directly on the first adapter plate 31 by semiconductor processes.

In operation, the light source 21 at the bottom of the back cavity 12 emits a light beam with a certain divergence angle, which is irradiated to the back of the movable mirror 11 and reflected back to the bottom of the back cavity 12 to irradiate on the first adapter plate 31 to form a light spot. When the micromirror operates, the movable mirror surface 11 of the micromirror chip 1 is deflected, and the light spot formed on the first transfer plate 31 by the light source 21 is also displaced accordingly. When the micromirrors are deflected to different angles, the light spots are located at different positions on the first transfer plate 31, and the light energy received by the photoelectric device 22 is different. By arranging one or more photoelectric devices 22, the phase information deflected by the micromirror can be converted into corresponding photoelectric information in real time, and the corresponding photoelectric information is transmitted to a control circuit of the micromirror through an electric interconnection structure, so that the driving signal of the micromirror is adjusted, and the real-time control of the movement of the micromirror is realized through photoelectric feedback.

Compared with the common micro-mirror control device based on piezoresistive feedback, capacitive feedback and the like, the device provided by the embodiment of the invention is suitable for more scenes. Compared with piezoresistive feedback, the device is less affected by external temperature change and can work normally under more extreme temperature environment. Compared with capacitive feedback, the device does not need to introduce an additional capacitive structure, and is suitable for micromirror chips 1 of almost all driving types, including electrostatic driving, electromagnetic driving, piezoelectric driving and electrothermal driving micromirrors. In addition, the device is completely based on the current common components or mature process technology, is simple and stable, and has good feasibility.

Fig. 2-7 are partial top views of the micromirror control device based on electro-optical feedback according to the embodiment of the invention, which are simplified for illustration, and only the key light source 21 and the optoelectronic device 22 are retained and simplified, and the rest of the structure on the first adapter plate 31 is omitted.

Alternatively, the movable mirror 11 is a movable mirror of a one-dimensional micromirror or a two-dimensional micromirror.

Referring to fig. 2, a solid black dot represents the center of the moving light spot at a certain time, and when the one-dimensional micromirrors deflect, the light spot generated by the light source 21 and reflected to the first transfer plate 31 also moves. Assuming that point B is the center position of the light spot when the micromirror deflects to the maximum angle, when the micromirror moves periodically, the center of the light spot moves back and forth between B-a-C, the optical energy obtained by the optoelectronic device 22 also changes periodically, and generates a periodically changing electrical signal corresponding to the phase of the micromirror chip 1. The phase of the current deflection of the movable mirror surface 11 of the micromirror can be determined by analyzing the periodically changing electrical signal, and the micromirror chip 1 is controlled.

Referring to fig. 3, 2

photoelectric devices

22a and 22b are integrated on the first transfer plate 31, and for a one-dimensional micromirror, the light spot projected onto the first transfer plate 31 can be uniquely determined by the 2 photoelectric devices 22 at any position, so as to directly obtain the phase information of the current deflection of the movable mirror 11.

Referring to fig. 4, for the two-dimensional micromirror, if 2

optoelectronic devices

22a and 22b are not collinear with the light source 21 device, when the micromirror makes periodic motion, the light spot projected onto the first transfer plate 31 also makes periodic motion, and the optical energy obtained by the

optoelectronic devices

22a and 22b also changes periodically, and generates a periodically changing electrical signal corresponding to the phase of the micromirror chip 1. By analyzing the periodically changing electrical signal, the phase of the current deflection of the movable mirror surface 11 can be determined, thereby realizing the feedback control of the micro-mirror chip 1.

With reference to fig. 4, in some embodiments, the two-dimensional micromirrors make periodic line-by-line scanning movements, and the centers of the light spots projected onto the first transfer plate 31 move along the trajectory. For any point on the trace, the determination can be made by the signals fed back from the 2

optoelectronic devices

22a and 22b in combination with the time domain information. For example, the signal generated by the photoelectric device 22a is set to Ia, the signal generated by the photoelectric device 22b is set to Ib, and the difference I between the two signals is obtained as Ia-Ib. When the light spots are scanned line by line from top to bottom along the track,

for point a, I >0 since the spot center is closer to the first opto-electronic device 22 a; for point B, in contrast, I <0, and thus points a and B can be distinguished. Through calibration and design algorithm carried out in advance, the accurate position of the current spot center can be determined in a time domain according to the values and the variation trends of I, Ia and Ib.

Referring to fig. 5, the signal generated by the optoelectronic device 22 depends on the distance between the detector and the center of the light spot, and it can be known from simple mathematical calculations that any point in the two-dimensional plane can be determined by intersecting 3 circles whose centers are not collinear. Therefore, if 3 non-collinear

photoelectric devices

22a, 22b, and 22c are integrated on the first relay plate 31, the light spot projected onto the first relay plate 31 can be uniquely determined by the signals Ia, Ib, and Ic generated by the 3

photoelectric devices

22a, 22b, and 22c when moving to any position in the two-dimensional plane for the two-dimensional micromirror, thereby directly obtaining the phase information of the deflection of the current movable mirror surface 11.

Alternatively, the optoelectronic device 22 includes any one of a single-point type photodetector, a two-dimensional photoelectric position detector (PSD)22d, and a one-dimensional photoelectric position detector 22 e. That is, the photoelectric device 22 may employ a two-dimensional photoelectric position detector (PSD)22d or a plurality of one-dimensional photoelectric position detectors 22e, in addition to a single-point type photodetector.

Referring to fig. 6, in some embodiments, the two-dimensional photoelectric position detector 22d integrated at the bottom of the back cavity 12 can feed back the position information of the light spot in the two-dimensional plane at any time, and convert the position information into the phase information of the micromirror motion through an algorithm.

Referring to fig. 7, in some embodiments, the photoelectric position detector 22e integrated at the bottom of the back cavity 12 can determine the current operating state of the micromirror by comparing with the scanning locus of the micromirror calibrated in advance according to the position and time of the photoelectric signal generated by the passing light spot.

It should be noted that, the feedback method using the optoelectronic device 22 is various, and the shapes or the arrangement modes of the optoelectronic device 22 may be arranged in a regular shape or an irregular shape, where the regular shape includes but is not limited to a linear shape, a triangular shape, a square shape, a rectangular shape, an arc shape, a rectangular array, a circular array, and the like, and the irregular shape includes but is not limited to a curved shape, a scattered point, and the like. It should be understood that the above description is only for illustrating the shape and placement of the optoelectronic device 22, and should not be taken as limiting the scope of the present embodiment.

In some preferred embodiments, a filtering structure is further disposed above the optoelectronic device 22, so as to eliminate the influence of stray light on the feedback accuracy, and improve the sensitivity of the feedback system.

Fig. 8 is a schematic structural diagram of a micromirror control device based on electro-optical feedback according to an embodiment of the present invention (in the figure, the glass sealing lid on the top and the second interposer 32 on the bottom of the micromirror device are not shown), please refer to fig. 8, the embodiment shown in fig. 8 is substantially the same as the embodiment shown in fig. 1, and the main differences are: the back cavity 12 of the micromirror device shown in fig. 8 is formed by etching the substrate layer 15 through a DIRE process, and the sidewalls of the etched back cavity 12 are perpendicular to the device layer 13. The material of the first transfer plate 31 is glass and, depending on the bonding process chosen, a layer 6 of bonding material is also arranged between the substrate layer 15 and the first transfer plate 31.

Alternatively, the back cavity 12 may be processed by an anisotropic wet etching process to form a sidewall structure inclined to the device layer 13, so as to obtain a relatively larger space of the back cavity 12.

In contrast to the embodiment shown in fig. 1, the micromirror control device provided in this embodiment employs the glass first transfer plate 31, and the metal layer 315 is arranged on the surface of the glass first transfer plate 31. A part of the metal layer 315 is used as a bonding pad for welding the chip and the integrated light source 21 and the photoelectric device 22, and plays a role in wetting; the other part serves as a conductor layer for making electrical interconnections on the first interposer 31. A plurality of through hole structures filled with metal are further arranged on the first adapter plate 31 made of glass material, so as to realize electrical interconnection with the outside.

The first transfer plate 31 made of glass is transparent to light from both the back and the front. Thus, the light source 21 and/or the optoelectronic device 22 of the micro-mirror device can be either directly disposed inside the micro-mirror device, as shown in FIG. 3, or disposed outside the micro-mirror device, as an external integral module. If the light source 21 is disposed outside the micromirror device, the designer can freely add various optical components to control the light beam generated by the light source 21, and the size of the light spot projected on the first transfer plate 31 is no longer dependent only on the thickness of the light source 21 itself and the substrate layer 15. Therefore, the size of the micromirror device can be designed completely according to the requirements of the micromirror chip 1 itself, the overall thickness can be smaller, and the choice of the light source 21 and the design of the optical system are more free.

Fig. 9 is a schematic structural diagram of a micromirror control device based on electro-optical feedback according to an embodiment of the present invention, please refer to fig. 9, the embodiment shown in fig. 9 is basically the same as the embodiment shown in fig. 1, and the main differences are: the inclined side walls of the back cavity 12 of the device shown in fig. 9 provide sufficient back cavity 12 space, the area of the first adapter plate 31 within the back cavity 12 is sufficiently large, and therefore the ASIC chip 41 controlling the electro-optical feedback system is also integrated on the first adapter plate 31, disposed inside the back cavity 12. Through the design, external control circuits are reduced, noise signals caused by external circuits are reduced, the sensitivity of a feedback system is improved, and meanwhile, the integration level of the micro-mirror device is also improved. The first adapter plate 31 is also pre-formed with a plurality of photoelectric devices 22 by semiconductor process, so as to further improve the integration level and reduce the cost.

Fig. 10 is a schematic structural diagram of a micromirror control device based on electro-optical feedback according to an embodiment of the invention, please refer to fig. 10, which is different from the embodiment shown in fig. 1 in that: the light source 21 of the micro-mirror device 500 is integrated on the first interposer 31, and the optoelectronic device 22 is directly integrated on the second interposer 32 by a semiconductor process. The first adapter plate 31 is further provided with a plurality of light passing holes 312. One or more light-passing holes 312 are disposed above one of the optoelectronic devices 22 to control the light to pass in and out, and the light-passing holes 312 also have a filtering function to eliminate the influence of stray light on the feedback accuracy.

The number, size, etc. of the light passing holes 312 corresponding to each of the optoelectronic devices 22 can be adjusted according to the design, and the embodiment shown in fig. 5 is only used for illustrating the embodiment of the present invention and should not be construed as limiting the embodiment of the present invention.

Compared with the embodiment shown in fig. 1, the micro-mirror device increases the change of the light energy detected by the PD due to the movement of the light spot by providing the light-passing hole 312, and improves the sensitivity of the feedback system. Meanwhile, stray light can be filtered out by arranging the light through hole 312, and the noise of the feedback system is further reduced.

Fig. 11 is a schematic structural diagram of a micromirror control device based on optoelectronic feedback according to an embodiment of the present invention, please refer to fig. 11, in some embodiments, only the optoelectronic device 22 is integrated on the first interposer 31 of the micromirror device, and the light source 21 and the ASIC chip 41 are integrated on the second interposer 32. The first transfer plate 31 is formed with a plurality of cavity structures having different sizes through an etching process.

The light source 21 is placed on the second adapter plate 32, and the generated light beam is irradiated to the back of the movable mirror 11 through the corresponding perforated structure 3131 on the first adapter plate 31. With the thickness of the first relay plate 31, the distance d between the light source 21 and the back of the movable mirror 11 can be controlled, unlike the other embodiments in which the distance d is adjusted by controlling the thickness of the chip substrate layer 15.

In addition, compared with other embodiments in which the light source 21 and other devices are disposed inside the back cavity 12 of the micromirror, the present embodiment indirectly increases the space of the active back cavity 12 of the micromirror by disposing an additional cavity structure on the first adapter plate 31, improves air damping when the micromirror moves in a non-vacuum closed space, and does not need to dispose an additional spacing structure or increase the thickness of the substrate layer 15.

Fig. 12 is a schematic top view of the interposer of fig. 11 in the range of the back cavity 12, and referring to fig. 12, the central region of the first interposer 31 is provided with a protrusion structure 313 and is integrated with a plurality of optoelectronic devices 22. The second adapter plate 32 is provided with a light source 21, the center of the protrusion structure 313 is provided with a perforation structure 3131, and the perforation structure 3131 is located right above the light source 21. The raised structure 313 may be an island structure that is not connected to other structures of the first transfer plate 31. Alternatively, the raised structure 313 may be a unitary structure connected to other structures of the first transfer plate 31.

Specifically, the first interposer 31 and the second interposer 32 may be formed by processing a single SOI wafer through a semiconductor process, or may be formed by processing different materials, for example, processing the first interposer 31 with a single crystalline silicon wafer, and using a PCB as the second interposer 32.

Specifically, the side walls of the back cavity 12 may be in a vertical structure or an inclined structure.

Specifically, the control module includes an ASIC chip 41, the ASIC chip 41 is connected with the micromirror chip 1 and the electro-optical feedback module through an electrical interconnection structure, and preferably, the same ASIC chip 41 is used to control the micromirror device and the electro-optical feedback system.

Alternatively, the ASIC chip 41 is disposed outside the micromirror control device, or the ASIC chip 41 may be integrated on the first transfer plate 31 by soldering, or the ASIC chip 41 is directly integrated on the first transfer plate 31 by a semiconductor process.

Fig. 13 is a schematic structural diagram of a micromirror control device based on optoelectronic feedback according to an embodiment of the present invention, wherein a control module is connected to the micromirror chip 1 through a through-silicon via structure 51, please refer to fig. 13, and in some embodiments, an electrical interconnection structure includes the through-silicon via structure 51, a first bonding pad 52, a second bonding pad 53 and a metal wire layer; the silicon through hole structure 51 penetrates through the micro-mirror chip 1, the top end of the silicon through hole structure 51 is connected with the first bonding pad 52, the bottom of the silicon through hole structure 51 is connected with the second bonding pad 53, and the second bonding pad 53 is connected with the bonding pad 314 arranged on the transfer structure; the electrical signal for controlling the micromirror device is generated by the ASIC chip 41 and transmitted to the micromirror chip 1 through the through-silicon via structure 51 arranged on the micromirror chip 1 device. To ensure the proper operation of each electrical interconnection structure, the second bonding pad 53 on the bottom of the micromirror chip 1 is disposed on the insulating dielectric layer, and the second bonding pad 53 cooperates with the bonding pad 314 on the first adapter plate 31 for realizing the welding fixation of the electrical interconnection and the micromirror chip 1. The metal wire layer is disposed on the first interposer 31, and electrically interconnects the micromirror chip 1, the ASIC chip 41, the light source 21, and the photoelectric device 22 by cooperating with each pad structure. Specifically, the first pad 52, the second pad 53, and the pad on the first transfer board 31 may be a metal pad or a metal oxide pad.

Fig. 14 is a schematic structural diagram of a micromirror control device based on optoelectronic feedback according to an embodiment of the present invention, wherein a control module is connected to the micromirror chip 1 by bonding with a wire 55, referring to fig. 14, in some embodiments, an electrical interconnection structure includes a third pad 54 and a wire 55, one end of the wire 55 is connected to the third pad 54, and the other end of the wire 55 is connected to a pad 314 disposed on the adapting structure. The electrical signal for controlling the micromirror device is generated by the ASIC chip 41 and transferred to the metal pads of the micromirror device by means of wire bonding 55. The electrical signal for controlling the electro-optical feedback system is also generated by the ASIC chip 41 and transmitted to the light source 21 and the optoelectronic device 22 through the metal layer 315 arranged on the first adapter plate 31. The first adapter plate 31 is further arranged with a number of metal-filled via structures 311 for electrically interconnecting the ASIC with external circuitry.

As can be seen from the foregoing embodiments of the micromirror control device based on electro-optical feedback provided by the present invention, the micromirror control device provided by the embodiments of the present invention has the following beneficial effects:

1. compared with the technology based on a piezoresistive feedback system, the micromirror control device provided by the embodiment is hardly influenced by the temperature change of the external environment, can be applied to a harsher temperature environment, performs feedback control on the micromirror device in a wider temperature range, and has better stability.

2. Compared with the technology based on the capacitive feedback system, the micromirror control device provided by the embodiment is suitable for various driving types of MEMS micromirrors, not only static driving micromirrors, but also electromagnetic driving micromirrors, electrothermal driving micromirrors, piezoelectric driving micromirrors and the like, and has better applicability.

3. The micromirror control device provided by the embodiment can be directly packaged with the micromirror chip 1 at a chip level, even at a wafer level, and is more suitable for miniaturized equipment and has better integration level compared with other methods for controlling the micromirror by utilizing photoelectric feedback.

4. Compared with other methods for controlling the micromirror by utilizing photoelectric feedback, the micromirror control device provided by the embodiment improves the feedback sensitivity by designing a unique structure, improves the air damping of the micromirror during movement in a non-vacuum closed space, maintains the overall size of the micromirror device as much as possible, and has better performance.

It should be noted that: the precedence order of the above embodiments of the present invention is only for description, and does not represent the merits of the embodiments. And specific embodiments thereof have been described above. Other embodiments are within the scope of the following claims.

The embodiments in the present specification are all described in a progressive manner, the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments, so that the description is simple, and related parts may be referred to the part of the description of the method embodiment.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A micro-mirror control device based on photoelectric feedback is characterized by comprising a micro-mirror chip (1), a photoelectric feedback module, a switching structure and a control module; the micro-mirror chip (1) comprises a movable mirror surface (11) and a back cavity (12); the optoelectronic feedback module comprises a light source (21) and at least one optoelectronic device (22);

the movable mirror (11) is positioned at the top of the back cavity (12), the bottom of the back cavity (12) is connected with the adapter structure, the light source (21) and the at least one photoelectric device (22) are positioned at the bottom of the back cavity (12), and the light source (21) and the at least one photoelectric device (22) are both arranged on the adapter structure;

the movable mirror surface (11) can reflect light beams emitted by the light source (21) to the bottom of the back cavity (12) to form light spots, the at least one photoelectric device (22) is used for converting phase information deflected by the movable mirror surface (11) into corresponding photoelectric information in real time according to the light spots, and the control module is used for controlling the micro-mirror chip (1) and/or the photoelectric feedback module according to the photoelectric information.

2. The device according to claim 1, characterized in that said adapter structure comprises a first adapter plate (31) and a second adapter plate (32);

the first adapter plate (31) is connected with the bottom of the back cavity (12), and the second adapter plate (32) is arranged below the first adapter plate (31);

the first interposer plate (31) is connected to the second interposer plate (32) by an electrical interconnection perforation structure (311), the electrical interconnection perforation structure (311) penetrating the first interposer plate (31);

the light source (21) is arranged on the first adapter plate (31) or the second adapter plate (32), and the at least one optoelectronic device (22) is arranged on the first adapter plate (31) and/or the second adapter plate (32).

3. The device according to claim 2, characterized in that said first adapter plate (31) is provided with a plurality of light-passing holes (312);

the light through hole (312) corresponds to the light source (21) and/or the photoelectric device (22) arranged on the second adapter plate (32) up and down.

4. The device according to claim 2, characterized in that said first transfer plate (31) is formed with a cavity structure and a projection structure (313);

the convex structure (313) is arranged in the central area of the first adapter plate (31), a perforated structure (3131) is arranged on the convex structure (313), and the perforated structure (3131) corresponds to the light source (21) arranged on the second adapter plate (32) up and down;

the raised structure (313) is an island structure that is not connected to other structures of the first transfer plate (31), or the raised structure (313) is an integral structure that is connected to other structures of the first transfer plate (31).

5. The device according to claim 2, characterized in that the first adapter plate (31) is made of monocrystalline silicon or glass or PCB, the second adapter plate (32) is made of monocrystalline silicon or glass or ceramic or PCB, and the first adapter plate (31) and the second adapter plate (32) are made of the same or different materials;

when the switching structure is made of glass, the light source (21) and the photoelectric device (22) are arranged inside or outside the micro-mirror control device.

6. The apparatus of claim 1, wherein the control module comprises an ASIC chip (41);

the ASIC chip (41) is arranged outside the micromirror control device, or the ASIC chip (41) is welded in the adapter structure, or the ASIC chip (41) is directly integrated in the adapter structure through a semiconductor process;

the ASIC chip (41) is connected with the micromirror chip (1) and the electro-optical feedback module through an electrical interconnection structure.

7. The apparatus of claim 6, wherein the electrical interconnect structure comprises a through silicon via structure (51), a first pad (52) and a second pad (53), and a metal wire layer; the silicon through hole structure (51) penetrates through the micro-mirror chip (1), the top end of the silicon through hole structure (51) is connected with the first bonding pad (52), the bottom end of the silicon through hole structure (51) is connected with the second bonding pad (53), and the second bonding pad (53) is connected with a bonding pad (314) arranged on the switching structure;

or the electrical interconnection structure comprises a third bonding pad (54) and a lead (55), one end of the lead (55) is connected with the third bonding pad (54), and the other end of the lead (55) is connected with a bonding pad (314) arranged on the transfer structure.

8. The device according to claim 1, characterized in that the micromirror chip (1) comprises at least one device layer (13), at least one buried oxide layer (14) and a substrate layer (15),

the movable mirror (11) is arranged on the device layer (13);

the back cavity (12) is formed on the buried oxide layer (14) and the substrate layer (15), and the side wall of the back cavity (12) and the device layer (13) are perpendicular or inclined to each other;

the substrate layer (15) is connected with the switching structure;

the device layer (13), the buried oxide layer (14) and the substrate layer (15) are sequentially stacked.

9. The apparatus of claim 1,

the light source (21) is arranged on the switching structure in a conductive silver adhesive bonding or welding manner;

the photoelectric device (22) is arranged on the switching structure in a conductive silver adhesive bonding or solder welding mode, or the photoelectric device (22) is directly integrated on the switching structure through a semiconductor process.

10. The apparatus according to claim 1, wherein the movable mirror (11) is a one-dimensional micromirror or a movable mirror of a two-dimensional micromirror, and the optoelectronic device (22) comprises any one of a single-point type photodetector, a two-dimensional photoelectric position detector and a one-dimensional photoelectric position detector.