Micromirror chip, micromirror device and optical device

Abstract

The present disclosure belongs to the technical field of micro-electro-mechanical systems, and provides a micromirror chip, a micromirror device and an optical device. The micromirror chip comprises a substrate, a micromirror array, electrodes, an optical window and a fixed ring; the micromirror array is located on a first surface of the substrate, and the electrodes are located on a second surface of the substrate, the first surface being positioned opposite to the second surface in the thickness direction of the substrate; the fixed ring is fixed to the first surface of the substrate, the micromirror array being located in an in-ring space of the fixed ring; the optical window is fixed to the fixed ring and covers the micromirror array. When the micromirror chip is packaged, the micromirror array is first sealed within a sealed space formed by the substrate, the fixed ring and the optical window, so that during subsequent packaging processes, no tiny particle will fall into an environment where the micromirror array is located, which can improve the pass rate of packaged micromirror devices, thus improving the yield of the packaged micromirror devices.

Description

Micromirror chips, micromirror devices, and optical devices

[0001] This disclosure claims priority to Chinese patent application No. 202410163132.X filed on February 4, 2024, entitled “Micromirror chip, micromirror device and optical device,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to the technical field of micro-electromechanical systems, and in particular to a micromirror chip, a micromirror device, and an optical device. Background Art

[0003] Micromirror chips, such as micro-electro-mechanical-system (MEMS) micromirror chips, are devices used to change the path of light. They have advantages such as small size and sensitive response, and are widely used in optical communications, lidar, and optical projection.

[0004] During the packaging process of the micromirror chip, such as when fixing the micromirror bare chip on the substrate and when punching gold wire on the micromirror bare chip, the micromirror bare chip will be contaminated. For example, tiny particles will fall on the micromirror bare chip, thereby reducing the yield of the packaged micromirror device. Summary of the Invention

[0005] The present disclosure provides a micromirror chip, a micromirror device, and an optical device, which can improve the yield of the packaged micromirror device.

[0006] In a first aspect, the present disclosure provides a micromirror chip, the micromirror chip comprising a substrate, a micromirror array, electrodes, a light window, and a fixing ring;

[0007] The micromirror array is located on a first surface of the substrate, the electrodes are located on a second surface of the substrate, and the first surface and the second surface are opposite to each other in a thickness direction of the substrate;

[0008] The fixing ring is fixed on the first surface of the substrate, and the micromirror array is located in the inner space of the fixing ring. The light window is fixed on the fixing ring and covers the micromirror array.

[0009] In the solution disclosed in the present invention, during the packaging of the micromirror chip, the micromirror array is first sealed in a sealed space formed by the substrate, the fixing ring and the light window. Therefore, during the subsequent packaging process, no tiny particles will fall into the environment where the micromirror array is located, thereby improving the qualified rate of the packaged micromirror device, thereby improving the yield of the packaged micromirror device.

[0010] In a possible implementation, the light window is in the shape of a flat plate and has an angle α with the substrate, and the angle α is greater than a maximum rotation angle β of a rotatable micromirror in the micromirror array.

[0011] The maximum rotation angle β is the maximum rotation angle of all rotatable micromirrors. For example, the maximum rotation angles of all rotatable micromirrors are the same, which is β. For another example, the maximum rotation angles of all rotatable micromirrors are different, but β is the largest maximum rotation angle.

[0012] In the scheme shown in the present disclosure, no matter how many degrees the rotatable micromirror rotates, the light window and the rotatable micromirror are not parallel. As long as the light window and the rotatable micromirror are not parallel, the reflected light path of the light window will not fall within the scanning field of view of the rotatable micromirror, and the detector is arranged within the scanning field of view of the rotatable micromirror. Therefore, it can be achieved that the detector is only within the scanning field of view of the rotatable micromirror, and not on the reflected light path of the light window. Furthermore, the light reflected by the light window will not enter the detector. Furthermore, even if the light window has a certain reflectivity, the light reflected by the light window will not interfere with the light signal received by the detector.

[0013] For example, each micromirror in a micromirror array corresponds to a coupler, an optical fiber, and a detector. The light reflected by the micromirror enters the coupler, passes through the coupler into the optical fiber, and then enters the detector through the optical fiber. In order to prevent the light reflected by the optical window from entering the detector, it is only necessary to prevent the light reflected by the optical window from entering the coupler or to enter the coupler at a relatively large incident angle. The incident angle here refers to the angle between the light and the normal of the coupler. The smaller the incident angle, the closer it is to perpendicular to the coupler, and the higher the coupling efficiency. In this case, the light reflected by the optical window is coupled to the coupler with low efficiency.

[0014] In a possible implementation, the height of the fixing ring satisfies the following relationship:

[0015] L1 / H1≥tan(θ), L2 / H2≥tan(θ+2γ);

[0016] L1 is the minimum distance between the first micromirror located at the edge of the micromirror array and the fixing ring, and H1 is the height of the fixing ring near the first micromirror.

[0017] L2 is the minimum distance between the second rotatable micromirror located at the edge of the micromirror array, close to the light emission direction, and the fixed ring; H2 is the height of the fixed ring close to the second rotatable micromirror;

[0018] The θ is the maximum angle between the incident light and the normal of the horizontal plane where the substrate is located, and the γ is the maximum rotation angle of the second rotatable micromirror.

[0019] In the solution disclosed herein, the dimensions of the retaining ring satisfy L1 / H1 ≥ tan(θ), allowing light of all incident angles to strike any micromirror in the micromirror array. The dimensions of the retaining ring satisfy L2 / H2 ≥ tan(θ+2γ), allowing light reflected from any micromirror to exit the micromirror chip.

[0020] In a possible implementation, the inner surface of the light window has a first notch at a position close to the edge, and the top of the fixing ring is fixed in the first notch.

[0021] In the solution shown in the present disclosure, the first notch is used to enhance the fixing strength between the light window and the fixing ring on the one hand, and to achieve pre-positioning between the light window and the fixing ring on the other hand, to prevent the light window from sliding off the top of the fixing ring, or to prevent slippage between the light window and the fixing ring.

[0022] In a possible implementation, the inner surface of the fixing ring has a second notch at the top, and the inner surface of the light window is fixed in the second notch near the edge.

[0023] In the solution shown in the present disclosure, the second notch is used to enhance the fixing strength between the light window and the fixing ring on the one hand, and to achieve pre-positioning between the light window and the fixing ring on the other hand, to prevent the light window from sliding off the top of the fixing ring, or to prevent slippage between the light window and the fixing ring.

[0024] In one possible implementation, the fixing ring and / or the light window has a vent hole, which is used to connect the inner space and the outer space of the fixing ring before the high-temperature packaging process, and is sealed by a medium after the high-temperature packaging process.

[0025] In the solution shown in the present disclosure, the micromirror chip is in the package. In the high-temperature process, such as when the micromirror chip is welded on a substrate or welded on an RDL, although at high temperature, the presence of the vents can reduce the air pressure in the space inside the fixed ring, thereby avoiding damage to components in the space inside the ring under high pressure.

[0026] In the solution shown in the present disclosure, after the high-temperature process, the vent holes can be sealed by filling the vent holes with a medium to ensure that the inner space of the fixing ring is in a sealed state.

[0027] In a possible implementation, the light window has a vent hole, and a vertical projection of the vent hole on the substrate partially falls in the inner space of the fixing ring, and another partially falls on the fixing ring.

[0028] In the solution shown in the present disclosure, when the vent hole is sealed by dispensing glue, the glue can be attached to the fixing ring and will hardly fall into the inner space of the fixing ring.

[0029] In a possible implementation, the inner surface of the top portion of the ring wall of the fixing ring connected to the light window has a chamfer.

[0030] In the solution shown in the present disclosure, the chamfer can avoid incident light and outgoing light.

[0031] In a possible implementation, the ring wall of the fixing ring is in the shape of a trapezoidal column, and the area of ​​the ring wall near the top of the light window is smaller than the area of ​​the ring wall near the bottom of the substrate.

[0032] In the solution shown in the present disclosure, the area of ​​the top of the fixing ring is smaller than the area of ​​the bottom, which can avoid incident light and outgoing light on the one hand, and increase the strength of the ring wall of the fixing ring on the other hand.

[0033] In a possible implementation, both the outer surface and the inner surface of the light window are coated with anti-reflection films, and the inner surface of the light window is not coated with the anti-reflection film at a position fixed to the fixing ring.

[0034] In the solution shown in the present disclosure, there is no antireflection film on the inner surface of the light window at the position fixed to the fixing ring, which can avoid the antireflection film from fixing the light window and the fixing ring, making the fixation of the light window and the fixing ring more secure.

[0035] In a possible implementation, the first surface of the substrate has a sink at a position where the fixing ring is fixed, and the bottom of the fixing ring is fixed in the sink.

[0036] In the solution disclosed herein, because the walls surrounding the sink and the bottom of the sink are fixed to the retaining ring, compared to directly securing the retaining ring to the substrate surface, the sink significantly increases the contact area between the substrate and the retaining ring, thereby enhancing the adhesion (e.g., adhesive adhesion) between the substrate and the retaining ring, and thus increasing the fixing strength between the substrate and the retaining ring. Once the fixing strength between the substrate and the retaining ring is enhanced, the bonding strength between the substrate and the retaining ring is also enhanced, and the airtightness of the space within the retaining ring is also improved.

[0037] In a possible implementation, the roughness of the first surface of the substrate at a position where the fixing ring is fixed is greater than the roughness at other positions.

[0038] In the solution shown in the present disclosure, the fixing ring is fixed at a position of the substrate where the roughness is relatively large. The large roughness can be used to enhance the adhesion between the substrate and the fixing ring, thereby enhancing the fixing strength between the substrate and the fixing ring.

[0039] In a possible implementation, a distance between the light window and the first side of the substrate is greater than or equal to 100 um.

[0040] In the solution shown in the present disclosure, although the light window is fixed on the substrate of the micromirror bare chip, the distance between the light window and the substrate can be set to be large enough so that the light window will not interfere with the rotation of the rotatable micromirror in the micromirror array.

[0041] In a possible implementation, the fixing ring is made of glue, silicon or metal.

[0042] In the solution shown in the present disclosure, the fixing ring may be glue, and after the glue is cured, a ring-shaped fixing ring is formed.

[0043] In a possible implementation, the fixing ring and the substrate are fixed by gluing or bonding, and the light window and the fixing ring are fixed by gluing or bonding.

[0044] In the solution shown in the present disclosure, the fixing ring can also be made of silicon material or metal material. Then, the fixing ring and the substrate are fixedly connected by gluing or bonding, and the light window and the fixing ring are also fixedly connected by gluing or bonding.

[0045] In a possible implementation, the micromirror chip further includes a getter, and the getter is located in the inner space of the fixed ring.

[0046] In the solution shown in the present disclosure, the getter located in the enclosed space formed by the substrate, the fixed ring and the light window can absorb the gas in the enclosed space, such as moisture, to prevent the gas from affecting the rotation of the rotatable micromirrors in the micromirror array.

[0047] In one possible implementation, the electrode includes a first electrode and a second electrode for driving the rotation of a rotatable micromirror in a micromirror array, wherein the first electrode is located on the first surface of the substrate and in the outer space of the fixed ring, and the second electrode is located on the second surface of the substrate, wherein the number of the first electrodes is one or more, such as less than or equal to the number of the second electrodes, and the number of the second electrodes is greater than or equal to the number of rotatable micromirrors included in the micromirror array.

[0048] In the solution disclosed herein, the first electrode can be a negative electrode, and the second electrode can be a positive electrode. The rotatable micromirrors of the micromirror array can share a single first electrode. Therefore, the number of first electrodes is relatively small, and they can be arranged on the first surface of the substrate, on the same side as the micromirror array. Although the first electrode is on the same side as the micromirror array, it is located outside the fixed ring, so it does not affect the micromirror chip package. The first electrode is connected to peripheral circuitry.

[0049] In another embodiment, the number of first electrodes serving as negative electrodes may be multiple. The number of second electrodes serving as positive electrodes may be the same as the number of rotatable micromirrors, with one second electrode corresponding to one rotatable micromirror. Alternatively, the number of second electrodes may be greater than the number of rotatable micromirrors, with multiple second electrodes corresponding to one rotatable micromirror.

[0050] In one possible implementation, the electrode includes a first electrode and a second electrode for driving the rotation of a rotatable micromirror in a micromirror array, and the first electrode and the second electrode are both located on the second surface of the substrate, wherein the number of the first electrodes is one or more, such as less than or equal to the number of the second electrodes, and the number of the second electrodes is the same as the number of rotatable micromirrors included in the micromirror array, or the number of the second electrodes is greater than the number of rotatable micromirrors, such as the number of the second electrodes is an integer multiple of the number of rotatable micromirrors.

[0051] In the solution disclosed herein, all electrodes of the micromirror chip, that is, the first electrode and the second electrode, are arranged on the second surface of the substrate, and are located on a different side of the substrate from the micromirror array. Therefore, the electrodes of the micromirror chip are all in the outer space of the fixed ring, and will not affect the connection between the first electrode and the second electrode and the peripheral circuit in the micromirror chip package.

[0052] In a possible implementation, the micromirror chip further includes an electrode lead-out layer, the electrode lead-out layer is located on the second surface of the substrate, the electrode lead-out layer has electrodes, and the electrodes of the electrode lead-out layer are electrically connected to the electrodes on the second surface of the substrate.

[0053] In a possible implementation, the electrode lead-out layer is a through-silicon via (TSV) layer, the TSV layer has an annular region extending through the thickness direction, and the number of the annular regions is greater than or equal to the number of electrodes on the second surface of the substrate;

[0054] The TSV layer is conductive, and each electrode on the second surface of the substrate is electrically connected to an inner ring area surrounded by an inner ring of the annular area. The annular area is filled with a first insulating medium.

[0055] In the solution shown in the present disclosure, the inner ring area formed by the inner ring of the annular area forms the electrode of the TSV layer, and the annular area is filled with an insulating first medium to achieve electrical isolation between two adjacent inner ring areas.

[0056] In the solution disclosed herein, since the substrate is made of silicon and the TSV layer is also made of silicon, the TSV layer can also be considered as part of the substrate of the micromirror bare chip. Therefore, the micromirror bare chip also includes the TSV layer, that is, the TSV layer is also part of the micromirror bare chip.

[0057] In the solution where the micromirror chip includes a TSV layer, the TSV layer has a certain thickness. Therefore, the TSV layer can increase the overall thickness of the micromirror bare chip. Once the overall thickness of the micromirror bare chip is relatively large, the rigidity of the micromirror bare chip is relatively large, and it is not easy to deform during the packaging process.

[0058] In one possible implementation, the electrodes on the second surface of the substrate include drive electrodes and test electrodes, the drive electrodes are used to drive the rotatable micromirrors in the micromirror array to rotate, and the test electrodes are used to test the conductivity between the TSV layer and the connected substrate or RDL.

[0059] In the solution presented in this disclosure, the connection between a TSV layer and an RDL is used as an example. Each inner ring region of the TSV layer is connected to the RDL. Testing the conductivity between the TSV layer and the connected RDL essentially tests the conductivity at the connection between the inner ring region and the RDL. For example, if the inner ring region and the RDL are connected via solder balls, testing the conductivity between the solder balls and the inner ring region, as well as between the solder balls and the RDL, is crucial.

[0060] It should be noted that not all inner-ring areas are tested for conductivity with the RDL, as some inner-ring areas are connected to the drive electrodes. For example, if there are eight inner-ring areas, five of which are connected to the drive electrodes for inputting drive signals to the rotatable micromirror, and three are connected to the test electrodes (e.g., connected in series on a test link), then the conductivity test is performed on the inner-ring areas on the test link to see if they have good conductivity with the RDL.

[0061] In one possible implementation, the number of test electrodes is one or more (e.g., an odd number). These test electrodes can all be positive electrodes. To form a test link, one of the drive electrodes can be used as a negative electrode. For example, one of the first electrodes described above can be used as the negative electrode of the test link. In this way, each test electrode is connected to a first electrode to form a closed short circuit for testing. Alternatively, these test electrodes are all grounded to form a test link.

[0062] In one possible implementation, the number of test electrodes is two or more (e.g., an even number), such as two pairs of test electrodes, with one electrode in each pair serving as a positive electrode and the other as a negative electrode. Thus, the positive and negative electrodes of each pair of test electrodes are connected to form a closed short circuit for testing.

[0063] During the test, an ohmmeter is used to test the resistance in the short-circuit loop. If the resistance is relatively large, it means that the conductivity of at least one connection in the test link is poor. If the resistance is very small, it means that the conductivity of all connections in the test link is good.

[0064] It should be noted that the positive electrode and negative electrode of the drive link for driving the rotatable micromirror are respectively connected to the driver chip, so that the driver chip drives the rotatable micromirror to rotate. Alternatively, the positive electrode of the drive link for driving the rotatable micromirror is respectively connected to the positive electrode of the driver chip, while the negative electrode of the drive link and the negative electrode of the driver chip are connected to a common ground.

[0065] In a possible implementation, both the inner ring wall and the outer ring wall of the annular region are covered with the first medium;

[0066] A second medium is further filled between the first medium on the inner ring wall and the first medium on the outer ring wall. The thermal expansion coefficient of the second medium is between the thermal expansion coefficient of the first medium and the thermal expansion coefficient of the material in the inner ring area.

[0067] In the solution shown in the present disclosure, the annular region is not entirely filled with the first medium, but is filled with the first medium and the second medium, wherein the first medium plays a role of electrical isolation and the second medium plays a role of reducing thermal stress.

[0068] In a possible implementation, the second medium is made of polysilicon, such as doped polysilicon.

[0069] In a possible implementation, the TSV layer is made of single-crystal silicon, and the first medium is made of silicon oxide.

[0070] In the solution disclosed herein, the TSV layer is made of single-crystal silicon, the first medium is made of silicon oxide, and the second medium is made of polycrystalline silicon. Since both the TSV layer and the second medium are made of silicon, their thermal expansion coefficients are relatively close, and the thermal stress between the TSV layer and the second medium is relatively small. Therefore, the micromirror chip is not easily deformed under temperature changes.

[0071] In a possible implementation, the electrode lead layer is an electrode chip, and the area of ​​the electrode chip is larger than the area of ​​the substrate;

[0072] The upper surface of the electrode chip has an electrode at a position extending from the substrate, and the upper surface of the electrode chip is a surface facing the second surface of the substrate;

[0073] The electrodes on the upper surface of the electrode chip are electrically connected to the electrodes on the second surface of the substrate through wiring inside the electrode chip.

[0074] In a second aspect, a micromirror device is provided, comprising a substrate, a driver chip, and the micromirror chip according to the first aspect;

[0075] The micromirror chip is located on the substrate, and the driving chip is electrically connected to the micromirror chip.

[0076] In the solution shown in the present disclosure, the micromirror chip is electrically connected to the substrate or RDL through solder balls. Compared with the solution in which the micromirror chip is connected to the substrate or RDL through a pin connector, the solution in which electrical connection is achieved through solder balls is easier to achieve high-density arrangement because the size of the solder balls is small and the spacing between adjacent solder balls is small.

[0077] In a possible implementation, the micromirror device further includes a redistribution layer (RDL), the RDL is located on a surface of the substrate, the micromirror chip is located on an upper surface of the RDL, and the upper surface of the RDL is a surface facing away from the substrate.

[0078] In the solution shown in the present disclosure, since the material of the RDL is silicon, even if the area of ​​the RDL is relatively large, the surface of the RDL is still relatively flat, and the micromirror chip is easy to fix on the surface of the RDL.

[0079] In a possible implementation, the driver chip is located on an upper surface of the RDL, and the micromirror chip and the driver chip are electrically connected through the RDL.

[0080] In the solution shown in the present disclosure, the driver chip and the micromirror chip are located on the upper surface of the same RDL, so that the driver chip and the micromirror chip are electrically connected through the wiring inside the RDL. Alternatively, the RDL includes a first RDL and a second RDL, the micromirror chip is located on the first RDL, and the driver chip is located on the second RDL, and the first RDL and the second RDL are connected by wire bonding. In this way, the driver chip is welded separately on one RDL, so even if an error occurs in a driver chip during the welding process of the second RDL, it will not affect the micromirror chip and other driver chips, which can reduce the yield loss and improve the yield of the micromirror device.

[0081] In a possible implementation, the micromirror device further includes a connector, and the connector is located on a surface of the substrate, such as an upper surface or a lower surface of the substrate;

[0082] The micromirror chip and the connector are electrically connected to the substrate via the RDL, and the connector and the driving chip are electrically connected via a flexible circuit board (FPC).

[0083] In a possible implementation, the lower surface of the RDL has a plurality of anchor structures and a plurality of elastic structures, the anchor structures and the elastic structures are connected one-to-one, and the lower surface of the RDL is a surface facing the substrate;

[0084] The RDL is fixed to the substrate at the anchor structure position by a first glue, and is fixed to the substrate at other positions outside the anchor structure by a second glue. The elastic modulus of the first glue is greater than the elastic modulus of the second glue, and the second glue is flexible after being cured.

[0085] In the solution shown in the present disclosure, after the epoxy resin glue is cured, it has great rigidity, which makes the fixation of RDL and substrate more firmly. After the thermal conductive silicone is cured, it is relatively soft, which can release the stress generated during the bonding of RDL and substrate, reduce the residual stress between RDL and substrate, and make RDL less likely to deform after bonding to the substrate.

[0086] In a third aspect, an optical device is provided, comprising a laser and the micromirror device according to the second aspect, wherein the laser is used to emit an optical signal and the micromirror device is used to reflect an optical signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] FIG1 is a schematic diagram of a micromirror chip provided by an exemplary embodiment of the present disclosure;

[0088] FIG2 is a schematic top view of a micromirror chip provided by an exemplary embodiment of the present disclosure;

[0089] 3 is a schematic diagram of a micromirror chip provided by an exemplary embodiment of the present disclosure, in which a first electrode is on a first side of a substrate and a second electrode is on a second side of the substrate;

[0090] FIG4 is a schematic diagram of a micromirror chip in which a first electrode and a second electrode are both located on a second side of a substrate, provided by an exemplary embodiment of the present disclosure;

[0091] FIG5 is a schematic diagram of a micromirror chip with an angle between a light window and a substrate provided by an exemplary embodiment of the present disclosure;

[0092] FIG6 is a schematic diagram of a fixing ring fixed on a substrate according to an exemplary embodiment of the present disclosure;

[0093] FIG7 is a schematic diagram of a scanning field of view of a micromirror chip provided by an exemplary embodiment of the present disclosure;

[0094] FIG8 is a schematic diagram of a micromirror chip having a light window with a first gap provided by an exemplary embodiment of the present disclosure;

[0095] FIG9 is a schematic diagram of a micromirror chip having a fixing ring with a second gap provided by an exemplary embodiment of the present disclosure;

[0096] FIG10 is a schematic diagram of a micromirror chip in which both the light window and the fixing ring have gaps, provided by an exemplary embodiment of the present disclosure;

[0097] FIG11 is a schematic diagram of a micromirror chip having a substrate with a sink groove provided by an exemplary embodiment of the present disclosure;

[0098] FIG12 is a schematic top view of a micromirror chip including a getter according to an exemplary embodiment of the present disclosure;

[0099] FIG13 is a schematic diagram of a micromirror chip including a TSV layer provided by an exemplary embodiment of the present disclosure;

[0100] FIG14 is a schematic top view of an area near a certain annular area in FIG13;

[0101] FIG15 is a schematic diagram of a micromirror chip including an electrode chip provided by an exemplary embodiment of the present disclosure;

[0102] FIG16 is a schematic diagram of a micromirror chip packaged on a substrate according to an exemplary embodiment of the present disclosure;

[0103] FIG17 is a schematic diagram showing a micromirror chip and a driver chip packaged on a substrate according to an exemplary embodiment of the present disclosure;

[0104] FIG18 is a schematic diagram of a micromirror chip provided by an exemplary embodiment of the present disclosure, packaged on a substrate through RDL;

[0105] FIG19 is a schematic diagram showing a micromirror chip and a driver chip provided by an exemplary embodiment of the present disclosure, both of which are packaged on a substrate through the same RDL;

[0106] FIG20 is a schematic diagram showing a micromirror chip and a driver chip provided by an exemplary embodiment of the present disclosure, packaged on a substrate through different RDLs;

[0107] FIG21 is a schematic diagram showing a micromirror chip provided by an exemplary embodiment of the present disclosure connected to the outside via a connector;

[0108] FIG22 is a schematic diagram showing a micromirror chip and a driver chip provided by an exemplary embodiment of the present disclosure, both of which are packaged on a substrate through RDL, and the driver chip is connected to the outside through a connector;

[0109] FIG23 is a schematic diagram of an RDL fixed on a substrate according to an exemplary embodiment of the present disclosure;

[0110] FIG24 is a curve showing the relationship between the deformation of the RDL and the substrate when the RDL is bonded to the substrate with epoxy resin adhesive;

[0111] FIG25 is a curve showing the deformation transformation relationship of the RDL in a solution where the RDL anchor structure position is fixed to the substrate via epoxy resin glue, and the other positions are fixed to the substrate via thermal conductive silicone.

[0112] Description of Reference Numerals

[0113] 1. Substrate; 2. Micromirror array; 21. Micromirror; 21A. First micromirror; 21B. Second micromirror.

[0114] 3. Electrode; 31. First electrode; 32. Second electrode; 4. Light window.

[0115] 5. Fixed ring; 51. First side wall; 52. Second side wall; 53. Third side wall; 54. Fourth side wall.

[0116] 6. Getter.

[0117] 7. TSV layer; 71. Ring area; 72. Inner area of ​​the ring; 73. First dielectric; 74. Second dielectric; 8. Electrode chip.

[0118] 100, substrate; 200, driver chip; 300, micromirror chip; 400, RDL; 500, connector. DETAILED DESCRIPTION

[0119] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0120] The embodiments of the present application relate to micromirror chips, specifically micro-electro-mechanical-system (MEMS) micromirror chips. In the processing of micromirror chips, a bare micromirror chip is generally first produced through semiconductor processing. This bare micromirror chip is then packaged to obtain a packaged micromirror device. The packaged micromirror device is then applied to optical devices (such as laser ranging radars, optical cross-connects, and wavelength selective switches).

[0121] Because the micromirror die's micromirrors are exposed during the entire packaging process, tiny particles can land in the micromirror's environment. These particles can interfere with the mirror's rotation. Furthermore, these particles are electrically charged, affecting the mirror's drive signal. Therefore, whether these particles interfere with the mirror's rotation or affect its drive signal, they can reduce the yield of the packaged micromirror device.

[0122] In order to improve the yield rate of the packaged micromirror device, this embodiment provides a micromirror chip. Before being packaged on a substrate, the micromirror chip has sealed the micromirror to protect the micromirror. Therefore, during the packaging process, tiny particles can be prevented from falling into the environment where the micromirror is located, thereby improving the yield rate of the packaged micromirror device.

[0123] In this embodiment, the chip processed by semiconductor technology is called a micromirror bare chip, the chip with the light window 4 fixed is called a micromirror chip, and the chip packaged on the substrate is called a micromirror device.

[0124] The features of the micromirror chip are introduced below. Figures 1 and 2 are schematic structural diagrams of the micromirror chip, where Figure 2 is a top-down schematic diagram of the micromirror chip. The structure framed by the dotted box in Figure 1 is a micromirror bare chip processed by semiconductor technology, also called a micromirror bare die.

[0125] As shown in FIG1 , a micromirror chip includes a substrate 1 and a micromirror array 2. Specifically, the substrate 1 may be a silicon substrate. As shown in FIG2 , the micromirror array 2 is an array comprising a plurality of micromirrors 21 disposed on a first surface of the substrate 1. For example, the first surface of the substrate 1 has a plurality of micromirror grooves, each of which contains a micromirror.

[0126] The micromirror 21 is a tiny optical mirror with a size ranging from micrometers to millimeters, and is used to change the optical path of the optical signal.

[0127] In one example, the plurality of micromirrors 21 in the micromirror array 2 may all be rotatable micromirrors (referred to as rotatable micromirrors), which can rotate under a driving signal.

[0128] In another example, among the multiple micromirrors 21 in the micromirror array 2, some of the micromirrors 21 may be non-rotatable (i.e., fixed micromirrors), while others may be rotatable micromirrors. As described above, the rotatable micromirrors rotate in response to a driving signal, while the fixed micromirrors, once fabricated, cannot rotate.

[0129] For example, fixed micromirrors can be placed at specific locations of the micromirror array 2, such as at the edges of the array, while rotatable micromirrors can be placed at all other locations. For another example, in a rectangular array of micromirror array 2, fixed micromirrors can be placed at the top corners of the array, while rotatable micromirrors can be placed at all other locations.

[0130] In this embodiment, whether the micromirror array 2 includes fixed micromirrors and the specific positions of the fixed micromirrors in the micromirror array are not specifically limited. Unless otherwise specified below, the micromirrors described are all rotatable micromirrors.

[0131] In one example, since the micromirror array 2 includes rotatable micromirrors, in order to drive the micromirrors 21 in the micromirror array 2 to rotate, the micromirror chip will also include a driving component. The driving component is used to drive the rotatable micromirrors in the micromirror array 2 to rotate. Then, the driving component and the micromirror array are located on the same side of the substrate 1, so the driving component is also located on the first surface of the substrate 1 (the driving component is not shown in the drawings of this embodiment).

[0132] As described above, the first surface of the substrate 1 has a micromirror groove. Then, the driving component corresponds one-to-one to the rotatable micromirrors in the micromirror array. The driving component can be arranged in the micromirror groove, and each rotatable micromirror is arranged on a rotatable structure of the driving component. Under the action of the driving signal, the rotatable structure of the driving component rotates, thereby driving the rotatable micromirror to rotate.

[0133] In one example, if the micromirror array 2 includes a fixed micromirror, and the fixed micromirror does not need to rotate, then the fixed micromirror does not need a driving component to drive it. Therefore, the fixed micromirror is directly arranged on the first surface of the substrate 1, or directly arranged in a micromirror groove on the first surface of the substrate 1, or the fixed micromirror is arranged on the first surface of the substrate 1 through a fixed bracket. In this embodiment, the arrangement of the fixed micromirror is not specifically limited.

[0134] In one example, the driving component that drives the rotatable micromirror to rotate can be an electrostatic driving component or a piezoelectric driving component. This embodiment does not limit this. Since the solution described in this embodiment does not involve the driving component, the driving component will not be described in detail below.

[0135] The above is an introduction to the characteristics of the micromirror array 2. The following will introduce the characteristics of the electrodes that input the drive signal to the drive component that drives the rotatable micromirror to rotate.

[0136] In one example, in order to input a driving signal to a driving component that drives the micromirror to rotate, accordingly, referring to FIG1 , the micromirror chip includes an electrode 3, wherein the electrode 3 is a pad located on the surface of the substrate 1. Since the micromirror array 2 includes a plurality of rotatable micromirrors, each rotatable micromirror needs to input a driving signal through the electrode 3. Therefore, referring to FIG1 , the number of electrodes 3 is also multiple.

[0137] In one example, to form a signal loop, each driving component requires two electrodes, which can be referred to as a first electrode and a second electrode. Therefore, the electrode 3 of the micromirror chip includes a first electrode 31 and a second electrode 32, wherein one of the first electrode 31 and the second electrode 32 serves as a positive electrode and the other as a negative electrode. For example, the first electrode serves as a negative electrode and the second electrode serves as a positive electrode. Alternatively, the first electrode serves as a positive electrode and the second electrode serves as a negative electrode.

[0138] In one example, in order to reduce the number of electrodes, the negative electrodes of all rotatable micromirrors can be shared, and the rotatable micromirrors correspond one-to-one to the positive electrodes. Therefore, the number of first electrodes 31 can be one, and the number of second electrodes 32 is greater than or equal to the number of rotatable micromirrors.

[0139] In another example, the number of the first electrodes 31 may also be multiple. For example, the number of the first electrodes 31 is a, and the number of the rotatable micromirrors is b, where a≤b.

[0140] In another example, the number of the second electrodes 32 may also be greater than the number of the rotatable micromirrors, so that one rotatable micromirror corresponds to one or more second electrodes 32 .

[0141] In this embodiment, the number of the first electrodes 31 and the number of the second electrodes 32 are not specifically limited.

[0142] The positions of the first electrode 31 and the second electrode 32 on the substrate 1 will be described below, wherein the first electrode 31 and the second electrode 32 are both arranged on the surface of the substrate 1 .

[0143] As an example, as shown in FIG3 , the first electrodes 31 are relatively few in number and can be located on the same side of the substrate 1 as the micromirror array 2. For example, both are located on the first surface of the substrate 1. However, the first electrodes 31 are located outside the fixing ring 5 to facilitate subsequent electrical connection with the substrate 100 or the RDL (redistribution layer) 400 in the package. However, the second electrodes 32 are numerous and, if arranged on the same side as the micromirror array 2, would result in a larger area of ​​the micromirror chip. Therefore, referring again to FIG3 , the numerous second electrodes 32 can be arranged on the second surface of the substrate 1.

[0144] Among them, the first electrode 31 and the second electrode 32 are arranged according to the layout shown in Figure 3. In the subsequent packaging, the first electrode 31 can be connected to the substrate 100 or the RDL400 by wire bonding, and the second electrode 32 can be connected to the substrate 100 or the RDL400 by solder balls.

[0145] In another example, as shown in FIG4 , the first electrode 31 and the second electrode 32 are both arranged on the second surface of the substrate 1 . In this way, the first electrode 31 and the second electrode 32 can also be located in the outer space of the fixing ring 5 . Therefore, it is easier to seal the micromirror array 2 before packaging the micromirror chip.

[0146] The above is an introduction to the characteristics of the micromirror bare chip. The following will introduce the sealing of the micromirror array 2. Among them, the structure framed by the dotted boxes in Figures 1, 3 and 4 is the micromirror bare chip.

[0147] In one example, in order to seal the micromirror array 2 before packaging the micromirror bare chip, accordingly, referring to Figure 4, the micromirror chip also includes a light window 4 and a fixing ring 5, wherein the fixing ring 5 is fixed to the first surface of the substrate 1 and surrounds the micromirror array 2, that is, the fixing ring 5 is ring-shaped, and the micromirror array 2 is located in the inner space of the fixing ring 5.

[0148] Continuing to refer to FIG. 4 , the light window 4 is fixed on the top of the fixing ring 5 and covers the micromirror array 2 , so that the micromirror array 2 is sealed in a sealed space formed by the substrate 1 , the fixing ring 5 and the light window 4 .

[0149] It should be pointed out that, as described above, each rotatable micromirror in the micromirror array 2 is driven to rotate by a driving assembly. Therefore, the driving assembly used to drive the micromirror to rotate is also sealed in the sealed space formed by the substrate 1, the fixing ring 5 and the light window 4.

[0150] The electrode 3 needs to be connected to the package by wire bonding, pin insertion, or solder balls, so the electrode 3 is located in the space outside the fixing ring 5. For example, referring to FIG3 , in the solution where the first electrode 31 is located on the first surface of the substrate 1, the first electrode 31 is located in the space outside the fixing ring 5.

[0151] It can be seen that in the packaging of the micromirror chip, since the micromirror array 2 has been sealed, no tiny particles will fall into the environment where the micromirror array 2 is located during the packaging process, thereby improving the qualified rate of the packaged micromirror device and thus improving the yield of the packaged micromirror device.

[0152] The features of the light window 4 and the fixing ring 5 will be described below.

[0153] In one example, in order not to interfere with the rotation of the rotatable micromirror, the minimum distance between the light window 4 and the first surface of the substrate 1 can be greater than 100 μm, so that the micromirror 21 will not touch the light window 4 when it rotates to the set maximum rotation angle.

[0154] In one example, the light window 4 is made of a transparent material with high transmittance and low reflectance. For example, both the inner and outer surfaces of the light window 4 can be coated with an antireflection coating. For example, the antireflection coating can be applied to both the inner and outer surfaces of the light window 4. This antireflection coating can improve transmittance in a certain wavelength band, such as the 1100nm to 1700nm wavelength band.

[0155] In one example, because the inner surface of the light window 4 is fixed to the top of the fixing ring 5, to facilitate the fixing of the light window 4 to the fixing ring 5, the inner surface of the light window 4, where it is fixed to the fixing ring 5, does not have an antireflection coating. For example, when the antireflection coating is applied to the inner surface of the light window 4, the area for fixing to the fixing ring 5 is reserved and is not coated with the antireflection coating. In another example, after the entire inner surface of the light window 4 is coated with the antireflection coating, the antireflection coating in the area for fixing to the fixing ring 5 is removed.

[0156] It should be pointed out that the area on the inner surface of the light window 4 used to fix with the fixing ring 5 has no anti-reflection film. This is a theoretical situation. However, in actual processing, due to errors, anti-reflection films will be coated at some positions in this area.

[0157] In an example, the light window 4 may be in the shape of a flat plate, covering the top end of the fixing ring 5 , wherein the top end of the fixing ring 5 is also the end facing away from the substrate 1 .

[0158] In one example, although the reflectivity of the light window 4 is relatively low, the light window 4 still has a certain reflectivity, causing the light incident on the light window 4 to be reflected to the detector through the light window 4, causing interference with the light signal received by the detector (wherein, theoretically, the light penetrates the light window 4, is incident on the micromirror 21, is reflected by the micromirror 21, and the reflected light passes through the light window 4 and enters the detector).

[0159] In order to prevent the reflected light reflected by the light window 4 from entering the detector and interfering with the light signal received by the detector, accordingly, as shown in Figure 5, the light window 4 is flat and has an angle α with the horizontal plane of the substrate 1. The angle α is greater than the maximum rotation angle β of the rotatable micromirrors in the micromirror array 2.

[0160] The maximum rotation angle β is the maximum rotation angle of all rotatable micromirrors. For example, the maximum rotation angles of all rotatable micromirrors are the same, which is β. For another example, the maximum rotation angles of all rotatable micromirrors are different, but β is the largest maximum rotation angle.

[0161] In this way, no matter how many degrees the rotatable micromirror rotates, the light window 4 is not parallel to the rotatable micromirror. As long as the light window 4 is not parallel to the rotatable micromirror, the reflected light path of the light window 4 will not fall within the scanning field of view of the rotatable micromirror, and the detector is arranged within the scanning field of view of the rotatable micromirror. Therefore, it can be achieved that the detector is only within the scanning field of view of the rotatable micromirror, and not on the reflected light path of the light window 4. Furthermore, the light reflected by the light window 4 will not enter the detector. Furthermore, even if the light window 4 has a certain reflectivity, the light reflected by the light window 4 will not interfere with the light signal received by the detector.

[0162] It should be pointed out that in some solutions, the light reflected by the micromirror is coupled to the coupler, enters the optical fiber via the coupler, and then is incident on the detector (or output end) via the optical fiber. Therefore, in order to prevent the light reflected by the light window 4 from entering the detector, it is only necessary to prevent the light reflected by the light window 4 from entering the coupler. As long as it does not enter the coupler, it will not enter the detector via the optical fiber. Alternatively, the light reflected by the light window 4 enters the coupler at a relatively large incident angle (i.e., the angle with the normal of the coupler), reducing the optical coupling efficiency. The efficiency of coupling the light reflected by the light window 4 to the optical fiber is relatively low, so the light entering the detector is also relatively weak and can be ignored.

[0163] In one example, the inclination of the light window 4 can be set by the height of the fixing ring 5. For example, as shown in Figure 6, a schematic diagram of the fixing ring 5 is fixed on the first surface of the substrate 1. Referring to Figure 6, the fixing ring 5 includes a first side wall 51, a second side wall 52, a third side wall 53 and a fourth side wall 54, wherein the first side wall 51 and the second side wall 52 are positioned relative to each other, and the height of the first side wall 51 is greater than the height of the second side wall 52, the third side wall 53 and the fourth side wall 54 are positioned relative to each other, and the angle between the plane where the top of the third side wall 53 and the fourth side wall 54 is located and the plane where the substrate 1 is located is α. In this way, the light window 4 covers the top of the fixing ring 5, and the angle between the light window 4 and the substrate 1 is also α.

[0164] In one example, as shown in FIG6 , the height of the fixing ring 5 and the spacing between the fixing ring 5 and the micromirrors at the edge of the array affect the scanning field of view of the micromirror chip. The scanning field of view of the micromirror chip is the angle between the maximum incident light and the maximum outgoing light. Therefore, in order not to affect the scanning field of view of the micromirror chip, the dimensions of the fixing ring 5 satisfy the following relationship, as shown in FIG7 : L1 / H1 ≥ tan(θ), L2 / H2 ≥ tan(θ+2γ)

[0165] As shown in FIG7 , L1 represents the minimum distance between the first micromirror 21A, which is located near the incident direction of light and at the edge of the micromirror array 2, and the fixing ring 5, and H1 represents the height of the fixing ring 5 near the first micromirror 21A. The first micromirror 21A can be either a fixed micromirror or a rotatable micromirror.

[0166] 6 and 7 , light is typically incident on the micromirror chip from the upper left corner of the first sidewall 51 or the upper right corner of the second sidewall 52, parallel to the third sidewall 53. For example, as shown in FIG7 , light is incident on the micromirror chip from the upper left corner of the first sidewall 51. Then, as shown in FIG7 , L1 is the distance between the inner surface of the first sidewall 51 and the side of the first micromirror 21A closest to the first sidewall 51, and H1 is the height of the first sidewall 51.

[0167] Wherein, θ is the maximum angle between the incident light and the normal of the horizontal plane where the substrate 1 is located.

[0168] Therefore, as shown in FIG. 7 , the size of the fixing ring 5 satisfies L1 / H1 ≥ tan(θ), so that light of all incident angles can be incident on any micromirror 21 of the micromirror array 2 .

[0169] Continuing with FIG7 , L2 represents the minimum distance between the second micromirror 21B, located near the light emitting direction and at the edge of the micromirror array 2, and the fixing ring 5 , and H2 represents the height of the fixing ring 5 near the second micromirror 21B. For example, referring to FIG7 , L2 represents the distance between the inner surface of the second sidewall 52 and the side of the second micromirror 21B near the second sidewall 52 , and H2 represents the height of the second sidewall 52 .

[0170] 7 , the straight line M represents the normal to the horizontal plane where the substrate 1 is located, the straight line N represents the normal to the second micromirror 21B in the state when the second micromirror 21B is rotated to the maximum rotation angle γ, and the plane P represents the plane where the inner surface of the second side wall 52 is located.

[0171] Wherein, γ is the maximum rotation angle of the second micromirror 21B, which is less than or equal to the aforementioned β, where β is the largest maximum rotation angle of all rotatable micromirrors.

[0172] Referring to FIG7 , when the second micromirror 21B rotates by an angle of γ, the normal perpendicular to the second micromirror 21B also rotates by an angle of γ. Therefore, as shown in FIG7 , the angle between the straight line M and the straight line N is γ, where the straight line M can also be regarded as the normal of the second micromirror 21B when it is rotated by 0 degrees (i.e., parallel to the substrate).

[0173] Therefore, referring to FIG. 7 , when the second micromirror 21B rotates to the maximum rotation angle γ, the angle between the light reflected by the second micromirror 21B at the current rotation angle and the inner surface of the second sidewall 52 is θ+2γ.

[0174] Therefore, as shown in FIG7 , the size of the fixing ring 5 satisfies L2 / H2≥tan(θ+2γ), so that the light reflected by any micromirror can be emitted from the micromirror chip.

[0175] In one example, if the light window 4 is parallel to the substrate 1, H1 and H2 are equal; if the light window 4 is tilted relative to the substrate 1, the height H1 of the first side wall 51 is greater than the height H2 of the second side wall 52, and the difference between H1 and H2 is the product of L3 and tanα, where L3 is the distance between the inner surface of the first side wall 51 and the inner surface of the second side wall 52.

[0176] Therefore, the size of the fixing ring 5 satisfies the relationship shown in the above formula, so that the fixing ring 5 will not interfere with the scanning field of view of the micromirror chip.

[0177] It should be pointed out that the first micromirror 21A can be a rotatable micromirror or a non-rotatable fixed micromirror, and the second micromirror 21B can be a rotatable micromirror or a non-rotatable fixed micromirror. If the second micromirror 21B is a non-rotatable fixed micromirror, the maximum rotation angle γ of the above-mentioned second micromirror 21B is 0 degrees.

[0178] It should be noted that the values ​​of H1 and H2 need to take into account the height changes caused by the gluing or bonding of the light window 4 to the fixing ring 5 , as well as the height changes caused by the gluing or bonding of the fixing ring 5 to the substrate 1 .

[0179] In one example, as shown in FIG8 , the inner surface of the light window 4 has a first notch near the edge, and the top of the fixing ring 5 is fixed in the first notch.

[0180] As shown in FIG8 , the first notch can be an L-shaped notch located at the inner edge of the light window 4. Thus, both sidewalls of the notch are fixed to the fixing ring 5, increasing the fixing area (e.g., bonding area) and thereby strengthening the fixing strength between the fixing ring 5 and the light window 4.

[0181] Furthermore, the notch of the light window 4 and the fixing ring 5 are snap-fitted together. Therefore, the light window 4 is pre-positioned before being fixed to the fixing ring 5 to prevent it from falling off the top of the fixing ring 5. For example, for a tilted light window 4, pre-positioning the light window 4 on the top of the fixing ring 5 before fixing it can prevent the light window 4 from falling off the top of the fixing ring 5 or prevent slippage between the light window 4 and the fixing ring 5.

[0182] In another example, the first notch can be a recessed groove, such as one formed near the edge of the inner surface of the light window 4, with the top of the retaining ring 5 secured within the recessed groove. This creates a fixed relationship between the top of the retaining ring 5 and the bottom of the recessed groove, and between the sidewalls of the retaining ring 5 and the walls of the recessed groove, thereby strengthening the securing strength between the retaining ring 5 and the light window 4. The top of the retaining ring 5 is located within the recessed groove, effectively locking the top of the retaining ring 5 within the recessed groove. This allows the light window 4 to be pre-positioned on the top of the retaining ring 5 before being secured to the retaining ring 5, preventing it from slipping off the top of the retaining ring 5.

[0183] In another example, as shown in Figure 9, the inner surface of the fixing ring 5 is provided with a second notch at the top, and the inner surface of the light window 4, near the edge, is fixed in the second notch. As shown in Figure 9, the second notch is an L-shaped notch.

[0184] The second notch of the fixing ring 5 serves, on the one hand, to enhance the fixing strength between the light window 4 and the fixing ring 5, and on the other hand, to pre-position the light window 4 to prevent the light window 4 from sliding off the top of the fixing ring 5 or from slipping between the light window 4 and the fixing ring 5.

[0185] In another example, as shown in FIG10 , both the light window 4 and the fixing ring 5 have notches. For example, the light window 4 has a first notch, and the fixing ring 5 has a second notch. The first notch of the light window 4 matches the second notch of the fixing ring 5, and the first notch of the light window 4 is engaged with the second notch of the fixing ring 5. The cooperation between the first notch of the light window 4 and the second notch of the fixing ring 5 not only serves to limit the light window 4 but also further increases the fixing area (e.g., bonding area) between the light window 4 and the fixing ring 5, thereby improving the fixing strength.

[0186] It should be noted that the black filling at the connection between the light window 4 and the fixing ring 5 in Figures 8 to 10 represents the fixing area between the two, for example, the black area represents the adhesive area or the bonding area.

[0187] In one example, the material of the fixing ring 5 may be glue, and then the light window 4 and the substrate 1 are fixed by gluing, and the glue is cured to form the fixing ring 5 .

[0188] In another example, the retaining ring 5 can be made of silicon, glass, fused quartz, or metal. The retaining ring 5 and substrate 1 can be fixed together using glue or bonding. The retaining ring 5 and light window 4 can also be fixed together using glue or bonding.

[0189] Among them, this embodiment does not specifically limit the material of the fixing ring 5. For example, the material of the fixing ring 5 can be selected to have a thermal expansion coefficient between the thermal expansion coefficient of the light window 4 and the thermal expansion coefficient of the substrate 1. In this way, the thermal stress of the micromirror chip can be reduced, making the micromirror chip less likely to deform or crack under a large temperature difference.

[0190] In one example, in order to enhance the fixation between the fixing ring 5 and the substrate 1, as shown in FIG11 , a groove can be opened on the first surface of the substrate 1 at the position where the fixing ring 5 is fixed, and the bottom of the fixing ring 5 can be fixed in the groove, wherein the black filling at the connection between the fixing ring 5 and the substrate 1 in FIG11 represents the fixed area of ​​the two, such as the black area represents the adhesive area or the bonding area.

[0191] Since the groove walls around the groove and the groove bottom of the groove are fixed to the fixing ring 5, compared with the fixing ring 5 being directly fixed on the surface of the substrate 1, it is obvious that the solution of providing the groove can increase the contact area between the substrate 1 and the fixing ring 5, thereby enhancing the adhesion between the substrate 1 and the fixing ring 5 (such as glue adhesion), thereby enhancing the fixing strength between the substrate 1 and the fixing ring 5.

[0192] In one example, the groove on the first surface of the substrate 1 can also be replaced by an L-shaped notch, wherein the L-shaped notch faces the outer space of the fixing ring 5, and the bottom of the ring wall of the fixing ring 5 is fixed in the L-shaped notch.

[0193] In one example, the roughness of the first surface of substrate 1 at the location where it is secured to retaining ring 5 can be greater than the roughness at other locations. Retaining ring 5 is secured at a location on substrate 1 where the roughness is greater. This greater roughness can enhance the adhesion between substrate 1 and retaining ring 5, thereby increasing the securing strength between substrate 1 and retaining ring 5.

[0194] The roughness can be increased by etching multiple grooves on the first surface of the substrate 1, corresponding to the area where the retaining ring 5 is mounted, to create an uneven surface in that area, thereby increasing the surface roughness of that area. Alternatively, a film can be applied to the first surface of the substrate 1, corresponding to the area where the retaining ring 5 is mounted, to increase the roughness of that area through the film layer.

[0195] Once the fixing strength between the substrate 1 and the fixing ring 5 is enhanced, the bonding strength between the substrate 1 and the fixing ring 5 is also enhanced, and the airtightness of the space inside the fixing ring 5 is also enhanced.

[0196] In one example, the process of etching a trough or a groove on the first surface of the substrate 1 can be carried out in etching a micromirror mounting groove. For example, when a micromirror mounting groove is opened on the first surface of the substrate 1, a trough and / or a groove can be opened in the mounting area of ​​the fixing ring 5.

[0197] In one example, the wall of the fixing ring 5 can be a trapezoidal column, with the top of the fixing ring 5 fixed to the light window 4 having a smaller area than the bottom of the fixing ring 5 fixed to the substrate 1. This can increase the strength of the wall of the fixing ring 5. The wall of the fixing ring 5, for example, as shown in FIG6 , includes a first side wall 51, a second side wall 52, a third side wall 53, and a fourth side wall 54.

[0198] In another example, as shown in Figure 7, the top of the ring wall of the retaining ring 5, on the inner surface facing the inner ring space, has a chamfer. For example, the inner surface of the top of the first side wall 51 of the retaining ring 5 is chamfered, and the inner surface of the top of the second side wall 52 is also chamfered. The chamfer can avoid incident and outgoing light. As shown in Figure 7, the chamfer is to cut the right-angled edge connecting the top and inner surface of the first side wall 51 into an inclined surface.

[0199] In one example, to prevent excessive pressure in the interior of the fixing ring 5 during high-temperature processes during packaging, the fixing ring 5 may have a vent a, as shown in FIG6 . For example, the vent a may be provided on any sidewall of the fixing ring 5 . The vent a is connected to the interior of the fixing ring 5 , thereby preventing excessive pressure in the environment surrounding the micromirror array 2 during high-temperature processes.

[0200] In another example, the vent hole a may also be provided on the light window 4 .

[0201] In one example, in order not to affect the airtightness of the space within the ring, the vent a can be sealed after the high-temperature process is completed. For example, welding the micromirror chip to the substrate is a high-temperature process. Then, after the high-temperature welding of the micromirror chip is completed, the vent a can be sealed with a medium.

[0202] In another example, the micromirror chip is arranged in a housing with good airtightness during application, so the vent a does not need to be sealed.

[0203] In one example, in the packaging process of the micromirror chip, after the vent hole a completes the exhaust operation, the vent hole a can also be sealed, for example, by dispensing glue in the vent hole a and using a solidified glue to seal the vent hole a.

[0204] To prevent glue from flowing into the inner space of the fixing ring 5 during glue dispensing in the vent hole a and affecting the rotation of the rotatable micromirror, the vent hole a on the light window 4 is positioned as close to the fixing ring 5 as possible. For example, the vertical projection of the vent hole a on the substrate 1 partially falls within the inner space of the fixing ring 5, while the other part falls on the fixing ring 5. In other words, the vent hole a on the light window 4 is not only provided on the light window 4, but also on the fixing ring 5. The portion of the vent hole a on the fixing ring 5 may or may not extend through the entire height of the fixing ring 5.

[0205] In this way, when the vent hole a is sealed by glue dispensing, the glue can be attached to the fixing ring 5 and hardly falls into the inner space of the fixing ring 5.

[0206] In another example, for the solution of opening a vent hole a on the light window 4, the aperture of the vent hole a is relatively small. In this way, when the vent hole a is sealed by dispensing glue, the glue adheres to the hole wall of the vent hole a, so the glue is not easy to flow into the ring space inside the fixing ring 5.

[0207] In one example, as shown in FIG12 , the micromirror chip may further include a getter 6, which is located on the first surface of the substrate 1 and in the inner space of the fixing ring 5. For example, as shown in FIG12 , the getter 6 is located between the fixing ring 5 and the micromirrors at the array edge of the micromirror array 2.

[0208] The getter 6 is used to absorb gas and moisture in the closed space surrounded by the substrate 1 , the fixing ring 5 and the light window 4 , and can be formed by coating a getter film layer on the first surface of the substrate 1 .

[0209] In one example, the inner surface of the fixing ring 5 can be coated with an absorbent film layer, which is used to absorb gas and moisture in the enclosed space surrounded by the substrate 1, the fixing ring 5 and the light window 4, wherein the inner surface of the fixing ring 5 is the surface facing the space inside the ring.

[0210] In one example, the getter 6 and the getter film layer on the inner surface of the fixing ring 5 may both be present in the micro-environment chip, or one of the two may be present in the micro-mirror chip.

[0211] The getter 6 on the first surface of the substrate 1 is also a getter film layer, and the getter film layer on the inner surface of the fixing ring 5 can be made of the same material.

[0212] In one example, the outer surface of the fixing ring 5 can be coated with a light-shielding film to prevent interference from stray light in the environment, wherein the outer surface of the fixing ring 5 is the surface facing the space outside the ring. In another example, the material of the fixing ring 5 can also be a material with relatively low transmittance, which can also prevent stray light in the environment from entering the space inside the fixing ring 5 and causing interference.

[0213] In one example, as shown in FIG13 , which is a schematic structural diagram of a micromirror chip, the micromirror chip may further include an electrode lead-out layer, the electrode lead-out layer being located on the second side of the substrate 1, the electrode lead-out layer having electrodes, and the electrodes of the electrode lead-out layer being electrically connected to the electrodes on the second side of the substrate 1.

[0214] As shown in FIG13 , the electrode lead-out layer is a through-silicon via (TSV) layer 7. The TSV layer 7 has an annular region 71 extending through the thickness. As shown in FIG13 and FIG14 , a through-hole extending through the thickness of the TSV layer 7 is formed between the inner and outer walls of the annular region 71. The through-hole is filled with a dielectric, such as a first dielectric 73 or a first dielectric 73 and a second dielectric 74.

[0215] The number of the annular regions 71 may be equal to the number of the electrodes 3 on the second surface of the substrate 1 , and the electrodes 3 on the second surface of the substrate 1 are connected one-to-one with the inner regions 72 of the annular regions 71 .

[0216] Among them, the material of the TSV layer 7 is silicon, which is conductive. Therefore, the inner ring area 72 surrounded by the inner ring of the annular area 71 can serve as the electrode of the TSV layer 7 and be electrically connected to the electrode 3 on the second surface of the substrate 1. Alternatively, the inner ring area 72 can also be called a conductive path, connecting the electrode 3 on the second surface of the substrate 1.

[0217] In one example, the electrodes 3 on the second surface of the substrate 1 can all be driving electrodes for driving the rotatable micromirror to rotate. The first electrode 31 and the second electrode 32 described above are both driving electrodes, except that one of the first electrode 31 and the second electrode 32 is a positive driving electrode and the other is a negative driving electrode.

[0218] As an example, if all the electrodes 3 on the second surface of the substrate 1 are second electrodes 32, then each second electrode 32 is connected to one inner ring region 72. For another example, if the electrodes 3 on the second surface of the substrate 1 include at least one first electrode 31 and all second electrodes 32, then each of the at least one first electrode 31 is connected to one inner ring region 72, and each of all second electrodes 32 is connected to one inner ring region 72. If the electrodes 3 on the second surface of the substrate 1 include one first electrode 31 and three second electrodes 32, and there are four inner ring regions 72, then one inner ring region 72 is connected to the first electrode 31, and three inner ring regions 72 are connected one-to-one to the three second electrodes 32.

[0219] In one example, the electrodes 3 on the second surface of the substrate 1 include not only driving electrodes (ie, the first electrode 31 and the second electrode 32 ), but also test electrodes, wherein the test electrodes are used to test the conductivity between the TSV layer 7 and the connected substrate 100 or RDL 400 .

[0220] As shown in Figure 18, the connection between TSV layer 7 and RDL 400 is shown. Each inner ring area 72 of TSV layer 7 is connected to RDL 400. Therefore, testing the conductivity between TSV layer 7 and the connected RDL 400 is also testing the conductivity between inner ring area 72 and RDL 400. For example, if inner ring area 72 and RDL 400 are connected via solder balls, then the conductivity between the solder balls and inner ring area 72, as well as the conductivity between the solder balls and RDL 400, is tested.

[0221] It should be noted that not all inner-ring areas 72 are tested for conductivity with the RDL 400. This is because some inner-ring areas 72 are also connected to drive electrodes (such as the second electrode 32). For example, there are eight inner-ring areas 72, of which five are connected to drive electrodes (such as the second electrode 32) for inputting drive signals to the rotatable micromirror, and three are connected to test electrodes (such as these three inner-ring areas 72 are connected in series on the test link). Therefore, when testing conductivity, the conductivity between the inner-ring areas 72 located on the test link and the RDL 400 is tested for good conductivity.

[0222] As an example, the number of test electrodes is one or more (e.g., an odd number). For example, these test electrodes are positive electrodes. Then, to form a test link, one of the drive electrodes can be used as a negative electrode. For example, one of the first electrodes described above can be used as the negative electrode of the test link. Alternatively, the other end of each test link is grounded.

[0223] As an example, the number of the test electrodes is two or more (such as an even number). For example, in each pair of test electrodes, one test electrode is a positive electrode, and the other test electrode is a negative electrode.

[0224] Regardless of whether the number of test electrodes is odd or even, the positive and negative electrodes of each test link must be connected, or the negative electrode of each test link must be grounded, forming a closed short circuit. During testing, an ohmmeter is used to measure the resistance of this closed short circuit. A high resistance indicates poor continuity at at least one connection in the test link. A low resistance indicates good continuity at all connections in the test link.

[0225] It should be noted that the positive and negative electrodes of the drive link used to drive the rotatable micromirror are connected to the positive and negative electrodes of the driver chip, respectively, so that the driver chip drives the rotatable micromirror to rotate. Alternatively, the positive electrode of the drive link is connected to the positive electrode of the driver chip, while the negative electrode of the drive link and the negative electrode of the driver chip are connected to a common ground.

[0226] Regardless of whether all the electrodes 3 on the lower surface of the substrate 1 are driving electrodes or include driving electrodes and test electrodes, all the electrodes 3 on the lower surface of the substrate 1 (i.e., the second surface) are led to the bottom of each inner ring area 72 through each inner ring area 72 of the TSV layer 7. The bottom of the inner ring area 72 is a position far away from the substrate 1.

[0227] Continuing with FIG14 , the annular region 71 is filled with a first insulating dielectric 73 to electrically isolate two adjacent inner-ring regions 72. The first dielectric 73 may be silicon oxide. FIG14 is a schematic top view of a portion of the annular region 71 in FIG13 .

[0228] In one example, as shown in reference figure 13, if the ring width d of the annular region 71 is relatively large, then when silicon oxide is deposited in the annular region 71, on the one hand, the growth cycle of silicon oxide is relatively long, which will extend the production cycle of the micromirror chip. On the other hand, the first medium 73 is silicon oxide, and the material of the TSV layer 7 is single crystal silicon. The thermal expansion coefficients of silicon oxide and silicon are quite different, resulting in relatively large thermal stress, which makes the micromirror chip prone to deformation under temperature changes.

[0229] If the annular region 71 has a relatively large width d, it can be filled with a first dielectric 73 and a second dielectric 74, where the thermal expansion coefficient of the second dielectric 74 lies between that of the first dielectric 73 and that of the material within the inner region 72. For example, as shown in FIG14 , the inner and outer walls of the annular region 71 are both covered with the first dielectric 73, while the second dielectric 74 is filled between the first dielectric 73 on the inner wall and the first dielectric 73 on the outer wall. This reduces thermal stress in the TSV layer 7.

[0230] The second dielectric 74 may be polysilicon.

[0231] In this way, the material of the TSV layer 7 is single crystal silicon, the material of the second medium 74 is polycrystalline silicon, and the TSV layer 7 and the second medium 74 are both made of silicon. Therefore, the thermal expansion coefficients of the two are relatively close, and the thermal stress between the TSV layer 7 and the second medium 74 is relatively small. Therefore, the micromirror chip is not easily deformed under temperature changes.

[0232] In one example, because the substrate 1 is made of silicon and the TSV layer 7 is also made of silicon, as shown in FIG13 , during the processing of the micromirror bare chip, the TSV layer 7 and the substrate 1 grow together to form the overall substrate of the micromirror bare chip. At the bottom of the overall substrate, multiple annular regions 71 are etched along the thickness direction. However, the annular regions 71 do not penetrate the thickness of the overall substrate, so the overall substrate is divided into the substrate 1 without the annular regions 71 and the TSV layer 7 with the annular regions 71. Therefore, the TSV layer 7 is part of the micromirror bare chip.

[0233] Because the micromirror bare chip includes the TSV layer 7, and the TSV layer 7 has a certain thickness, the TSV layer 7 can increase the overall thickness of the micromirror bare chip. Once the overall thickness of the micromirror bare chip is relatively large, the rigidity of the micromirror bare chip is relatively large, and it is not easy to deform during the packaging process.

[0234] In another example, the electrode lead-out layer may not be the TSV layer 7, but a chip (recorded as electrode chip 8). As shown in Figure 15, the electrode lead-out layer is the electrode chip 8. The area of ​​the electrode chip 8 is larger than the area of ​​the substrate 1. The upper surface of the electrode chip 8 has an electrode at a position extending from the substrate 1. The upper surface of the electrode chip 8 is the surface facing the second side of the substrate 1. The electrode 81 on the upper surface of the electrode chip 8 is electrically connected to the electrode 3 on the second side of the substrate 1 through the wiring inside the electrode chip 8.

[0235] In another example, the electrode lead-out layer may also include a TSV layer 7 and an electrode chip 8 . In this solution, the inner ring area 72 of the TSV layer 7 is electrically connected to the electrode of the electrode chip 8 through the wiring inside the electrode chip 8 .

[0236] It should be pointed out that the sealing process of the micromirror array 2, that is, the fixing process of the fixing ring 5 and the light window 4, can be regarded as a pretreatment process before the micromirror bare chip is packaged, or it can be regarded as the first step of the micromirror bare chip packaging. Regardless of which step it is regarded as, the sealing of the micromirror array 2 is before the micromirror bare chip is packaged on the substrate.

[0237] In the embodiment of the present disclosure, when packaging the micromirror chip, the micromirror array 2 is first sealed in the sealed space formed by the substrate, the fixing ring and the light window. Therefore, in the subsequent packaging process, no tiny particles will fall into the environment where the micromirror array 2 is located, thereby improving the qualified rate of the packaged micromirror device, thereby improving the yield of the packaged micromirror device.

[0238] This embodiment further provides a micromirror device, which can be applied in an optical cross connect (OXC) or a wavelength selective switch (WSS).

[0239] As shown in FIG16 , the micromirror device includes a substrate 100 , a driving chip 200 and the micromirror chip 300 described above, wherein the micromirror chip 300 includes a TSV layer 7 as an example.

[0240] The driving chip 200 is electrically connected to the micromirror chip 300 so as to transmit a driving signal to the electrodes 3 of the micromirror bare chip to drive the rotatable micromirrors in the micromirror array 2 to rotate.

[0241] In one example, as shown in FIG. 16 , the micromirror chip 300 is located on the substrate 100 . For example, the micromirror chip 300 is fixed on the substrate 100 by gluing, bonding, or welding.

[0242] Continuing with FIG. 16 , the substrate 100 has circuits, and electrodes may also be arranged on the surface of the substrate 100. The inner ring region 72 of the micromirror chip 300 is electrically connected to the substrate 100 via solder balls, which in turn are electrically connected to the electrodes 101 on the surface of the substrate 100 via wiring within the substrate 100. The electrodes 101 on the surface of the substrate 100 are used to electrically connect to other devices, such as the driver chip 200.

[0243] The solder balls mentioned above and the solder balls mentioned below may also be replaced by stupus bumps and solder bumps.

[0244] In this way, the electrode on the second surface (i.e., the lower surface) of the substrate 1 is connected to the substrate 100 through the TSV layer 7. If there is also an electrode on the first surface (i.e., the upper surface) of the substrate 1, the electrode on the upper surface of the substrate 1 can be connected to the substrate 100 by wire bonding.

[0245] As shown in FIG17 , the driver chip 200 may also be arranged on the surface of the substrate 100 , and the driver chip 200 and the substrate 100 are connected via solder balls. Furthermore, the driver chip 200 and the micromirror chip 300 are electrically connected via wiring inside the substrate 100 .

[0246] In another example, in a solution where the driving chip 200 is not on the substrate 100 , the driving chip 200 and the micromirror chip 300 can be electrically connected through a connector and a flexible printed circuit (FPC), as shown in FIG. 21 .

[0247] In another example, as shown in FIG18 , the micromirror device may further include a redistribution layer (RDL) 400 , where the RDL 400 is located on the surface of the substrate 100 , and the micromirror chip 300 is located on the upper surface of the RDL 400 , wherein the upper surface of the RDL 400 is also the surface facing away from the substrate 100 .

[0248] The micromirror chip 300 and the RDL 400 are connected via solder balls. The upper surface of the RDL 400 has electrodes. The electrodes 410 of the RDL 400 are connected to the electrodes 101 of the substrate 100 via wire bonding.

[0249] In this way, the electrode on the second surface (i.e., the lower surface) of the substrate 1 is connected to the RDL400 through the TSV layer 7. If there is also an electrode on the first surface (i.e., the upper surface) of the substrate 1, the electrode on the upper surface of the substrate 1 can be connected to the RDL400 by wire bonding.

[0250] In one example, the RDL 400 is made of silicon, allowing it to maintain a relatively flat surface even over a large area. However, the substrate 100 is made of ceramic, making it difficult to maintain a flat surface over a large area. Therefore, the micromirror chip 300 is directly attached to the surface of the RDL 400, rather than the substrate 100. This strengthens the connection between the micromirror chip 300 and the RDL 400 and reduces packaging stress.

[0251] In one example, the driver chip 200 can be fixed on the upper surface of the RDL400. As shown in Figure 19, the driver chip 200 and the micromirror chip 300 are both located on the upper surface of the RDL400, and the driver chip 200 and the micromirror chip 300 are electrically connected through the wiring inside the RDL400.

[0252] In another example, as shown in FIG20 , the RDL 400 may include a first RDL 401 and a second RDL 402 , wherein the first RDL 401 and the second RDL 402 are both fixedly located on the surface of the substrate 100 , the micromirror device 300 is located on the upper surface of the first RDL 401 , and the driver chip 200 is located on the upper surface of the second RDL 402 , for example, the driver chip 200 corresponds one-to-one to the second RDL 402 , and the first RDL 401 and the second RDL 402 are connected by wire bonding.

[0253] In the solution shown in FIG20 , the driver chip 200 is individually soldered on an RDL. Therefore, even if an error occurs in the soldering process of a certain driver chip 200 on the second RDL 402, it will not affect the micromirror chip 300 and other driver chips, thereby reducing yield loss and improving the yield of the micromirror device.

[0254] In the solution shown in FIG19 , since the micromirror chip 300 and all the driver chips 200 are arranged on the RDL 400 , if an error occurs in the process of soldering one driver chip 200 on the RDL, the entire micromirror device may be scrapped.

[0255] It should be noted that in the solution where the micromirror chip includes the RDL 400, the driver chip 200 may be located not on the upper surface of the RDL 400 but on the surface of the substrate 100. Alternatively, the driver chip 200 may be located neither on the surface of the RDL 400 nor on the surface of the substrate 100, but may be electrically connected to the micromirror chip 300 via the connector 500 and the FPC. In this solution, the connector 500 may be soldered to a surface (such as the upper or lower surface) of the RDL 400.

[0256] As shown in Figures 21 and 22, the micromirror device also includes a connector 500. The connector 500 can be located on the upper surface of the substrate 100 or on the lower surface of the substrate 100. Referring to Figure 21, the connector 500 can be used to achieve electrical connection between the driver chip 200 and the micromirror chip 300. Referring to Figure 22, the connector 500 can also be used to achieve electrical connection between the driver chip 200 and the control circuit of the micromirror device.

[0257] The connector 500 and the substrate 100 may be connected by solder ball welding or wire bonding.

[0258] In one example, in a solution where the micromirror device includes the RDL 400 , there may be no wiring on the surface or inside of the substrate 100 . Such a substrate 100 does not serve as an electrical interconnection but rather as a support.

[0259] In one example, in a solution where the micromirror device includes RDL400, the lower surface of RDL400 can have multiple anchor structures (such as grooves, protrusions, stripes, etc.) and multiple elastic structures, wherein the anchor structures and the elastic structures are connected one by one, and the lower surface of RDL400 is also the surface facing the substrate 100.

[0260] The RDL 400 is fixed to the substrate 100 at the anchor structure using a first adhesive, while the RDL 400 is fixed to the substrate 100 at locations outside the anchor structure using a second adhesive. The elastic modulus of the first adhesive is greater than that of the second adhesive, and the second adhesive has a certain degree of flexibility after curing. For example, the first adhesive may be epoxy resin adhesive, and the second adhesive may be thermally conductive silicone adhesive.

[0261] After the epoxy resin glue is cured, it is relatively hard and has high rigidity, so that the connection between the RDL 400 and the substrate 100 is relatively firm.

[0262] The thermal conductive silicone is relatively soft after curing, and can absorb the residual stress in the fixation of the RDL400 and the substrate 100, so that cracking and deformation are not likely to occur between the RDL400 and the substrate.

[0263] The elastic structure connected to the anchor structure is used to absorb the residual stress generated by the connection between the anchor structure of the RDL 400 and the substrate 100 through the epoxy resin glue.

[0264] In one example, as shown in FIG23 , which is a schematic diagram of an RDL 400 located on a substrate 100 , referring to FIG23 , the shape of the RDL 400 is square or rectangular, and anchor structures may be set at the four vertex positions of the RDL 400 .

[0265] In one example, a coordinate system is established with the center position of the RDL400 in Figure 23 as the coordinate origin, the plane where the RDL is located as the xoy plane, and the thickness direction of the RDL as the z axis, and the deformation of the RDL400 is simulated through simulation software.

[0266] FIG24 is a diagram illustrating a relationship curve between the x-axis coordinate position of the RDL 400 and the z-axis deformation after the RDL 400 is bonded to the substrate 100, in a solution where the RDL 400 and the substrate 100 are fixed entirely with epoxy resin glue. FIG25 is a diagram illustrating a relationship curve between the x-axis coordinate position of the RDL 400 and the z-axis deformation after the RDL 400 and the substrate 100 are bonded with epoxy resin glue and thermally conductive silicone glue, as described above.

[0267] 24 and 25 , the RDL 400 and the substrate 100 are bonded together using epoxy resin glue and thermally conductive silicone rubber, which can reduce the residual stress in the fixation of the RDL 400 and the substrate 100 , and the RDL 400 is not easily deformed after bonding.

[0268] In the embodiment of the present disclosure, referring to Figures 16 to 22, the solution in which the micromirror chip 300 is electrically connected to the substrate 100 or RDL400 through solder balls is compared with the solution in which the micromirror chip 300 is connected to the substrate 100 or RDL400 through a pin connector. The solution in which the electrical connection is achieved through solder balls is easier to achieve high-density arrangement because the size of the solder balls is small and the spacing between adjacent solder balls is small.

[0269] This embodiment further provides an optical device, which includes a laser and the above-mentioned micromirror device, wherein the laser is used to emit light signals, and the micromirror device is used to reflect light signals through its micromirrors.

[0270] The optical device may be an optical cross connect (OXC) or a wavelength selective switch (WSS) in the field of optical communications.

[0271] For example, the optical device includes two micromirror devices, a first micromirror device and a second micromirror device. In application, the optical signal emitted by one or more lasers is incident on an optical fiber in the first optical fiber array, and the optical signal emitted by the optical fiber is incident on a micromirror of the first micromirror device, reflected by the micromirror of the first micromirror device to a micromirror of the second micromirror device, and then reflected by the micromirror of the second micromirror device to an optical fiber in the second optical fiber array, thereby realizing the switching of the optical signal from one optical fiber in the first optical fiber array to another optical fiber in the second optical fiber array.

[0272] The optical device can also be a laser ranging radar in the field of laser ranging. For example, a light signal emitted by a laser is incident on a micromirror device, reflected by the micromirrors of the micromirror device to the object being measured, and the light reflected by the object enters a detector, thereby measuring the distance between the object and the micromirror device.

Claims

1. A micromirror chip, characterized in that: The micromirror chip comprises a substrate (1), a micromirror array (2), electrodes (3), a light window (4) and a fixing ring (5); The micromirror array (2) is located on a first surface of the substrate (1), the electrode (3) is located on a second surface of the substrate (1), and the first surface and the second surface are positioned opposite to each other in a thickness direction of the substrate (1); The fixing ring (5) is fixed to the first surface of the substrate (1), and the micromirror array (2) is located in the inner ring space of the fixing ring (5); the light window (4) is fixed on the fixing ring (5) and covers the micromirror array (2).

2. The micromirror chip according to claim 1, wherein: The light window (4) is in the shape of a flat plate and has an angle α with the substrate (1), and the angle α is greater than the maximum rotation angle β of the rotatable micromirrors in the micromirror array (2).

3. The micromirror chip according to claim 1 or 2, characterized in that: The height of the fixing ring (5) satisfies the following relationship: L1 / H1≥tan(θ), L2 / H2≥tan(θ+2γ); The L1 is the minimum distance between the first micromirror (21A) located at the edge of the micromirror array (2) and the fixing ring (5), and the H1 is the height of the fixing ring (5) near the first micromirror (21A); L2 is the minimum distance between a second micromirror (21B) located near the light emitting direction and at the edge of the micromirror array (2) and the fixing ring (5); H2 is the height of the fixing ring (5) near the second micromirror (21B); The θ is the maximum angle between the incident light and the normal line of the horizontal plane where the substrate (1) is located, and the γ is the maximum rotation angle of the second micromirror (21B).

4. The micromirror chip according to any one of claims 1 to 3, characterized in that: The inner surface of the light window (4) has a first notch, and the top of the fixing ring (5) is fixed in the first notch.

5. The micromirror chip according to any one of claims 1 to 4, characterized in that: The inner surface of the fixing ring (5) has a second notch, and the light window (4) is fixed in the second notch.

6. The micromirror chip according to any one of claims 1 to 5, characterized in that: The outer surface and the inner surface of the light window (4) are both coated with anti-reflection films, and the inner surface of the light window (4) has no anti-reflection film at a position fixed to the fixing ring (5).

7. The micromirror chip according to any one of claims 1 to 6, characterized in that: The inner surface of the top of the ring wall of the fixing ring (5) connected to the light window (4) has a chamfer.

8. The micromirror chip according to any one of claims 1 to 7, characterized in that: The area of the ring wall of the fixing ring (5) close to the top of the light window (4) is smaller than the area close to the bottom of the substrate (1).

9. The micromirror chip according to any one of claims 1 to 8, characterized in that: The first surface of the substrate (1) has a sink at a position where it is fixed to the fixing ring (5), and the bottom of the fixing ring (5) is fixed in the sink.

10. The micromirror chip according to any one of claims 1 to 9, characterized in that: The roughness of the first surface of the substrate (1) at a position where the substrate is fixed to the fixing ring (5) is greater than the roughness at other positions.

11. The micromirror chip according to any one of claims 1 to 10, characterized in that: The micromirror chip further comprises a getter (6), and the getter (6) is located in the inner ring space of the fixing ring (5).

12. The micromirror chip according to any one of claims 1 to 11, characterized in that: The electrode (3) comprises a first electrode (31) and a second electrode (32) for driving the rotatable micromirrors in the micromirror array (2) to rotate; The number of the first electrodes (31) is greater than or equal to 1 and less than or equal to the number of the second electrodes (32), and the number of the second electrodes (32) is greater than or equal to the number of rotatable micromirrors included in the micromirror array (2); The first electrode (31) is located on the first surface of the substrate (1), and in the outer space of the fixing ring (5), and the second electrode (32) is located on the second surface of the substrate (1).

13. The micromirror chip according to any one of claims 1 to 11, characterized in that: The electrode (3) comprises a first electrode (31) and a second electrode (32) for driving the rotatable micromirrors in the micromirror array (2) to rotate; The number of the first electrodes (31) is greater than or equal to 1 and less than or equal to the number of the second electrodes (32), and the number of the second electrodes (32) is greater than or equal to the number of rotatable micromirrors included in the micromirror array (2); The first electrode (31) and the second electrode (32) are both located on the second surface of the substrate (1).

14. The micromirror chip according to any one of claims 1 to 13, characterized in that: The micromirror chip further comprises a conductive through silicon via (TSV) layer (7), wherein the TSV layer (7) is located on the second surface of the substrate (1); The TSV layer (7) has an annular region (71) extending through the thickness direction, and the number of the annular region (71) is equal to the number of electrodes (3) on the second surface of the substrate (1); The electrodes (3) on the second surface of the substrate (1) are connected one by one to the inner ring areas (72) formed by the inner ring of the annular area (71), and each of the annular areas (71) is filled with a first insulating medium (73).

15. The micromirror chip according to claim 14, characterized in that: The electrodes (3) on the second surface of the substrate (1) include drive electrodes and test electrodes, the drive electrodes being used to drive the rotatable micromirrors in the micromirror array (2) to rotate, and the test electrodes being used to test the conductivity between the TSV layer (7) and the connected substrate (100) or RDL (400).

16. The micromirror chip according to claim 14 or 15, characterized in that: The inner ring wall and the outer ring wall of the annular area (71) are both covered with the first medium (73); A second medium (74) is further filled between the first medium (73) on the inner ring wall and the first medium (73) on the outer ring wall. The thermal expansion coefficient of the second medium (74) is between the thermal expansion coefficient of the first medium (73) and the thermal expansion coefficient of the material in the inner ring area (72).

17. A micromirror device, characterized in that: The micromirror device comprises a substrate (100), a driving chip (200), and a micromirror chip (300) according to any one of claims 1 to 16; The micromirror chip (300) is located on the substrate (100), and the driving chip (200) is electrically connected to the micromirror chip (300).

18. The micromirror device according to claim 17, wherein: The micromirror device further comprises a redistribution layer (RDL) (400), the RDL (400) being located on the surface of the substrate (100), the micromirror chip (300) being located on the upper surface of the RDL (400), and the upper surface of the RDL (400) being the surface facing away from the substrate (100).

19. The micromirror device according to claim 18, wherein: The driving chip (200) is located on the upper surface of the RDL (400), and the micromirror device (300) and the driving chip (200) are electrically connected via the RDL (400).

20. The micromirror device according to claim 18, wherein: The micromirror device further comprises a connector (500), and the connector (500) is located on the surface of the substrate (100); The micromirror chip (300) and the connector (500) are electrically connected via the RDL (400) and the substrate (100), and the connector (500) and the driving chip (200) are electrically connected via a flexible circuit board (FPC).

21. The micromirror device according to any one of claims 18 to 20, characterized in that: The lower surface of the RDL (400) has a plurality of anchor structures and a plurality of elastic structures, the anchor structures and the elastic structures are connected one by one, and the lower surface of the RDL (400) is a surface facing the substrate (100); The RDL (400) is fixed to the substrate (100) at the anchor structure position by a first glue, and the RDL (400) is fixed to the substrate (100) at other positions outside the anchor structure by a second glue, wherein the elastic modulus of the first glue is greater than the elastic modulus of the second glue, and the second glue is flexible after being cured.

22. An optical device, characterized in that: The optical device includes a laser and the micromirror device according to any one of claims 17 to 21, the laser is used to emit an optical signal, and the micromirror device is used to reflect an optical signal.

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