MEMS micromirror for improving light path blocking and manufacturing method thereof

Abstract

This invention relates to a MEMS micromirror and its fabrication method, specifically to a MEMS micromirror and its fabrication method that improves optical path obstruction. Without altering the processing conditions of the actuators and mirrors in the MEMS micromirror or affecting its normal operation, this invention optimizes the fixing frame by starting with the wafer cutting design of the MEMS micromirror. The fixing frame is transformed from a traditional closed frame into a non-closed frame with a notch, ensuring reliable support while allowing light emitted from the notch to exit directly during large-angle scanning. This completely solves the problem of light beam obstruction by the MEMS micromirror fixing frame itself during scanning.

Description

Technical Field

[0001] This invention relates to a MEMS micromirror and its fabrication method, specifically to a MEMS micromirror and its fabrication method that improves the problem of optical path obstruction caused by the micromirror's own structure during beam scanning. Background Technology

[0002] MEMS micromirrors are microelectromechanical systems chips implemented using semiconductor microfabrication technology. They are microactuators capable of precisely manipulating the reflection of laser beams and are widely used in laser scanning, laser projection displays, lidar, and optical communication. A MEMS micromirror mainly consists of a closed, fixed frame around its perimeter and a movable structure at the center of the frame, including a planar mirror and a driver. The planar mirror and driver are connected to the fixed frame via a torsion shaft and are suspended within the frame. Under the application of a specific driving signal, the planar mirror in the MEMS micromirror structure can twist around its axis under the action of the driving structure. When a laser beam is projected onto the planar mirror surface, the direction of the reflected laser beam changes as the mirror twists, thus achieving laser scanning.

[0003] In specific applications of MEMS micromirrors, the incident laser beam is typically projected onto the mirror surface from a point perpendicular to the mirror's torsion axis and at a certain angle to the plane of the mirror. After reflection by the torsional mirror surface, the laser beam can achieve an optical scanning angle range twice that of the mechanical torsion angle of the MEMS micromirror. However, due to the presence of a fixed frame around the MEMS micromirror, inevitably, when the scanning angle is large, some of the emitted light will be blocked by the fixed frame, resulting in partial loss of laser energy, or even complete blockage, thus limiting the scanning angle range. Figure 1 As shown in the figure, 1 represents the laser, 02 represents the closed fixed frame, and 3 represents the reflector. However, the fixed frame of the MEMS mirror is the anchor point of the planar reflector, and it is an indispensable and important structure for realizing the function of the MEMS micromirror. Therefore, exploring a suitable way to solve the problem of its obstruction of the optical path is of great significance for promoting the application of MEMS micromirrors and expanding their application scenarios.

[0004] Currently, solutions are generally sought from the perspective of chip structure design and microfabrication. One approach is to make the reflective mirror protrude from the fixed frame plane; however, this requires complex microfabrication techniques and processes, resulting in high manufacturing costs. Furthermore, the protruding structure hinders subsequent processing and assembly of the MEMS micromirror. Increasing the distance between the reflective mirror and the fixed frame is another solution, but this increases the footprint of a single chip, also raising costs. Besides cost factors, both of these solutions still suffer from the problem of frame obstruction of the optical path at specific angles, and cannot completely solve the optical path obstruction issue. Summary of the Invention

[0005] The purpose of this invention is to provide a MEMS micromirror that improves optical path obstruction and its fabrication method, thereby completely solving the problem of light beam obstruction by the MEMS micromirror fixing frame itself during the scanning process at a lower cost.

[0006] The concept of this invention is:

[0007] To completely solve the problem of beam obstruction by the fixed frame in a low-cost manner, this invention considers optimizing the fixed frame from the perspective of the MEMS micromirror wafer cutting design, without changing the processing conditions of the actuator and mirror in the MEMS micromirror or affecting the normal operation of the MEMS micromirror. The fixed frame is changed from a traditional closed frame to a non-closed fixed frame with a notch. While ensuring reliable support, during large-angle scanning, the emitted light that is blocked by the traditional fixed frame can be emitted directly from the notch, thereby completely solving the problem of beam obstruction by the MEMS micromirror fixed frame itself during scanning.

[0008] The technical solution of the present invention is to provide a MEMS micromirror that improves optical path obstruction, including a fixed frame and a movable structure located at the center of the fixed frame and connected to the fixed frame by a torsion beam, wherein the connection point between the torsion beam and the fixed frame is defined as an anchor point.

[0009] Its special feature is that the above-mentioned fixed frame is formed during the MEMS micromirror wafer cutting stage, and a notch is opened on the fixed frame. The notch is located on the frame edge where the anchor point is not located, so as to ensure that the emitted light is emitted directly from the notch during large-angle scanning.

[0010] Furthermore, the aforementioned fixing frame can be rectangular, circular, or other irregularly shaped; therefore, the present invention is applicable to all MEMS micromirrors with different structural forms.

[0011] Furthermore, for ease of processing, the length of the aforementioned notch is equal to the length of the side of the fixed frame where the other non-anchor point is located.

[0012] Furthermore, the torsion beam can be on the same side or opposite side of the movable structure, which includes a planar reflector and an actuator, wherein the reflector and the actuator can also be on the same side or opposite side.

[0013] Furthermore, the thickness of the movable structure can be the same as that of the fixed frame, or it can be thinner than the fixed frame.

[0014] This invention also provides a method for fabricating the above-mentioned MEMS micromirror with improved optical path obstruction, characterized by comprising the following steps:

[0015] Step 1: Determine whether both the upper and lower surfaces of the movable structure in the MEMS micromirror to be processed have a portion of their area coplanar with the fixed frame. If so, proceed to Step 2. Otherwise, attach the side of the movable structure that is concave to the plane of the fixed frame to the conventional film and proceed to Step 3.

[0016] Step 2: Project the specific structure of the MEMS micromirror chip onto the scribe film. Retain the adhesive layer on the scribe film corresponding to the non-closed fixing frame area and the chip-free area of ​​the wafer to fix the chip. De-adhesive layer corresponding to the movable structure area and the structural gap area until it is completely non-adhesive to make a patterned adhesive layer scribe film. Align and bond the MEMS micromirror wafer with the patterned adhesive layer scribe film.

[0017] Step 3: Cut the chip into a fixed frame shape according to the designed dicing path, which is a fixed frame with notches on the frame side where the non-anchor point is located.

[0018] Step 4: Expand the spacing of the MEMS micromirror chip array on the wafer through a film expansion process until it is easy to extract the core, forming a micromirror chip array with reasonable spacing between independent components.

[0019] Step 5: After cutting and expanding the entire wafer, remove the adhesive until the viscosity decreases, and then extract the core.

[0020] Furthermore, in step 2, the diced film is an adhesive film whose viscosity can be adjusted by applying specific external conditions.

[0021] Furthermore, the adhesive film mentioned above can be a UV-dissolving adhesive film or a pyrolytic adhesive film.

[0022] Furthermore, in step 2, the adhesive layer in all projection areas except for the fixed frame projection is debonded until it is completely non-adhesive, creating a patterned adhesive layer dicing film. This debonding is achieved using the following method:

[0023] It can be achieved by photomask-assisted light-based debonding or coating, by imprinting coating, or by mold-assisted point-to-point heating debonding. Alternatively, an additional graphic viscosity isolation film can be attached to the dicing film adhesive layer.

[0024] Furthermore, in step 2, when aligning and bonding the MEMS micromirror wafer with the scribe film of the patterned adhesive layer, the front side (reflective mirror surface) of the MEMS micromirror can be attached to the scribe film of the patterned adhesive layer, or the back side of the MEMS micromirror can be attached to the scribe film of the patterned adhesive layer.

[0025] The present invention also provides another method for fabricating the above-mentioned MEMS micromirror with improved optical path obstruction, characterized in that it includes the following steps:

[0026] Step 1: Determine whether both the upper and lower surfaces of the movable structure in the MEMS micromirror to be processed have a portion of their area coplanar with the fixed frame. If so, proceed to Step 2. Otherwise, attach the side of the movable structure that is concave to the plane of the fixed frame to the conventional film and proceed to Step 3.

[0027] Step 2: A patterned additive layer is fabricated on the non-enclosed fixing frame of the MEMS micromirror wafer using screen printing. This ensures good adhesion between the screen-printed paste and the non-enclosed fixing frame of the MEMS micromirror wafer, and that the paste surface is smooth. The MEMS micromirror wafer with the screen-printed additive layer is then bonded to a conventional film. The MEMS micromirror adheres to the conventional film through the screen-printed additive layer, while the MEMS micromirror wafer portion corresponding to the movable chip structure does not contact or adhere to the conventional film due to the presence of the screen-printed additive layer.

[0028] Step 3: Cut the chip into a fixed frame shape according to the designed dicing path;

[0029] Step 4: Expand the spacing of the MEMS micromirror chip array on the wafer through a film expansion process until it is easy to extract the core, forming a micromirror chip array with reasonable spacing between independent components.

[0030] Step 5: After cutting and expanding the entire wafer, remove the adhesive until the viscosity decreases, and then extract the core.

[0031] Furthermore, in step 2, the thickness of the screen-printed additive layer is 10-500um.

[0032] Furthermore, in step 2, the screen-printed layer is located on the side of the MEMS micromirror wafer with a larger printable area.

[0033] The beneficial effects of this invention are:

[0034] 1. This invention starts with the wafer cutting design of MEMS micromirrors. Ensuring reliable support, the fixing frame is transformed from a traditional closed frame to a non-closed frame with a notch. During large-angle scanning, the emitted light blocked by the traditional fixing frame can exit directly through the notch, thus completely solving the problem of beam obstruction by the MEMS micromirror fixing frame itself during scanning. Simultaneously, this fixing frame can be completed during the wafer cutting stage, without affecting the processing technology of the driver and reflector in the MEMS micromirror, and to a certain extent, reducing the chip size and cost.

[0035] 2. This invention uses a specially designed patterned adhesive dicing film or an added screen-printed layer on the corresponding part of the MEMS micromirror wafer frame to avoid the movable structure of the MEMS micromirror chip being adhered to the dicing film, thus creating conditions for subsequent chip cutting, film expansion and core extraction steps. The process is simple and reliable. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the scanning process of a MEMS micromirror using a traditional closed fixed frame.

[0037] In the diagram: 1-Laser, 02-Enclosed fixed frame, 3-Reflector;

[0038] Figure 2 This is a schematic diagram of the MEMS micromirror scanning process in the embodiment;

[0039] In the diagram: 1-Laser, 2-Unenclosed fixed frame, 3-Reflector, 14-Outgoing beam;

[0040] Figure 3 The figures provided are a top view and a cross-sectional view of the MEMS micromirror in the embodiment. Figure a is a top view of the MEMS micromirror; Figure b1 is a cross-sectional view along line Y in figure a, in which the torsion beam and the mirror are located on different sides; Figure b2 is a cross-sectional view along line Y in figure a, in which the torsion beam and the mirror are located on the same side; Figure c is a cross-sectional view along line X in figure a.

[0041] In the diagram: 2-non-enclosed fixed frame, 3-reflector, 4-torsion beam, 5-anchor point, 6-notch;

[0042] Figure 4 This is a schematic diagram of the patterned adhesive layer dicing film in the embodiment;

[0043] Figure 5 This is a schematic diagram of the wafer dicing channel design in Example 1;

[0044] Figure 6 The figures show a top view and a cross-sectional view of a MEMS micromirror using a traditional closed fixed frame. Figure a is a top view of the MEMS micromirror; Figure b1 is a cross-sectional view along line Y in figure a, where the torsion beam and the mirror are located on different sides; Figure b2 is a cross-sectional view along line Y in figure a, where the torsion beam and the mirror are located on the same side; and Figure c is a cross-sectional view along line X in figure a.

[0045] In the diagram: 02 - closed fixed frame, 3 - reflector;

[0046] Figure 7 This is a schematic diagram of the movable structure suspended within a non-enclosed fixed frame and recessed within the fixed frame in Example 1;

[0047] In the diagram: 2 - non-enclosed fixed frame, 8 - movable structure, 9 - recessed surface;

[0048] Figure 8This is a schematic diagram of a MEMS micromirror in Example 1, where the upper and lower surfaces of the movable structure suspended in a non-enclosed fixed frame are partially coplanar with the fixed frame.

[0049] In the figure: 2-non-enclosed fixed frame, 81-upper surface of movable structure, 82-lower surface of movable structure;

[0050] Figure 9 The patterned adhesive layer of the scribe film used in the MEMS micromirror in the embodiment corresponds to the fixing frame; where Figure a is the MEMS micromirror and Figure b is the patterned adhesive layer of the scribe film.

[0051] In the diagram, 2 represents a non-enclosed fixed frame, and 11 represents the adhesive area.

[0052] Figure 10 This is a flowchart of the method for fabricating a patterned adhesive layer scribe film in Example 1;

[0053] Figure 11 This is a schematic diagram of the MEMS micromirror array and the required dicing film patterned adhesive layer processed in Example 1; where a is the MEMS micromirror array and b is the required dicing film patterned adhesive layer.

[0054] Figure 12a This is a schematic cross-sectional view of the MEMS micromirror wafer adhered to the scribe film along the X-axis in Example 1.

[0055] Figure 12b This is a schematic diagram of the cross-section along the rear Y-axis of the MEMS micromirror wafer adhered to the dicing film in Example 1.

[0056] In the figure: 10 - MEMS micromirror wafer, 11 - adhesive region, 12 - desmearing region;

[0057] Figure 13 This is a schematic diagram of the screen-printed additive layer fabricated on the MEMS micromirror wafer in Example 2; where Figure a is a top view of the MEMS micromirror, Figure b is a cross-sectional view along line Y in Figure a, in which the torsion beam and the reflector are located on different sides; Figure c is a cross-sectional view along line X in Figure a.

[0058] In the diagram, 2-non-enclosed fixed frame, 3-reflector, 4-torsion beam, 5-anchor point, 6-notch, 7-screen printed additive layer;

[0059] Figure 14 This is a schematic diagram of the screen-printed additive layer and the conventional film adhered to the MEMS micromirror wafer in Example 2.

[0060] In the figure, 7-screen printing layer, 8-movable structure, 13-normally planned film. Detailed Implementation

[0061] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0062] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0063] The present invention envisions that if a MEMS micromirror could be developed from the dicing stage after the completion of MEMS micromirror wafer fabrication, which is easy to implement in terms of technology and can completely and effectively solve the problem of optical path obstruction, it would have great application value and economic benefits.

[0064] Based on this concept, this invention starts with the dicing design of MEMS micromirror wafers. At this stage, the fixing frame is optimized, such as... Figure 2 As shown, the fixing frame is changed from a traditional closed frame to a non-closed fixing frame with a notch. This fixing frame can be defined as a non-closed fixing frame 2 or a C-shaped fixing frame. During large-angle scanning, the outgoing light 14, which is blocked by the traditional fixing frame and reflected by the reflector 3, can directly exit from the notch, thus completely solving the problem of the MEMS micromirror fixing frame itself blocking the light beam during scanning. The size of this non-closed fixing frame 2 can be flexibly adjusted, while still ensuring the support reliability required by the MEMS chip frame, and can reduce the size of the chip to a certain extent. Figure 3 As shown, to ensure the long-term stability of the relative position and function of the movable structure of the MEMS micromirror (including the reflector 3 and the actuator), as well as the operability of subsequent MEMS micromirror assembly, the anchor points 5 of each torsion beam 4 need to be fixed to the same rigid support frame. Therefore, the notch 6 of the non-closed fixed frame 2 is opened on a frame side that is not where the anchor point 5 is located. The size of the notch 6 is sufficient to ensure that, during the set large-angle scanning process, the emitted light can be emitted directly from the notch 6 without being blocked by the fixed frame. The specific structural form of the fixed frame is not limited; it can be a rectangular, circular, or other irregularly shaped frame.

[0065] However, because the reflective structure of MEMS micromirrors is suspended and movable, the process of cutting a single chip from a whole wafer and the core extraction process differ significantly from that of conventional semiconductor chips (such as IC chips and LED chips). Conventional abrasive wheel cutting and laser cutting are unsuitable for MEMS micromirror wafer processing due to the significant impact of water impact and particulate contamination on the wafer performance. Currently, the main method applicable to MEMS micromirror wafer cutting is laser-modified stealth cutting. During this cutting process, MEMS micromirror wafers also have specific requirements for the film-coating materials used. These materials must not only meet general requirements such as fixing the wafer and the cut individual chips, and providing expandable films, but also prevent the movable structure from being damaged by film adhesion during core extraction. Current solutions mainly involve optimizing the MEMS micromirror design to allow the use of existing conventional films. While design optimization can achieve the desired goals, this approach comes at the cost of higher chip processing costs and more complex processing flows.

[0066] To achieve the smooth three-step process of cutting, expanding, and core extraction of a MEMS micromirror chip with a non-enclosed fixing frame 2, this invention provides the following: Figure 4 As shown, a dicing film with patterned adhesive layers is fabricated by retaining the adhesive layers on the dicing film corresponding to the non-closed fixing frame area and the wafer chipless area for fixing the chip, while de-adhesive layers corresponding to the movable structure area and the structural gap area are de-adhesive until they are completely non-adhesive. Figure 4 The striped areas correspond to the adhesive layer in the non-enclosed fixing frame area and the chip-free area of ​​the wafer, while the blank areas are adhesive-free areas, corresponding to the movable structure area and the structural gap area. This prevents the movable structure from adhering to the dicing film during the dicing process. Alternatively, a screen-printed additive layer can be added to the non-enclosed fixing frame and the chip-free area of ​​the MEMS micromirror wafer. Then, the MEMS micromirror wafer with the screen-printed additive layer is bonded to the conventional dicing film before dicing. This also prevents the movable structure from adhering to the dicing film, creating conditions for subsequent chip dicing, film expansion, and core extraction steps. The process is simple and reliable.

[0067] With the assistance of patterned adhesive dicing film or screen-printed additive layers, regardless of whether the movable structure of the MEMS micromirror is coplanar with the front or back of the chip, or not coplanar with either side, since the movable structure is never bonded to the dicing film, the film expansion process after cutting will not cause the movable microstructure to deform or be damaged as the film is stretched. Ultimately, this ensures that the cutting, film expansion, and core extraction of MEMS micromirrors with non-closed fixed frames can be successfully achieved.

[0068] The present invention will be described in detail below with reference to specific embodiments.

[0069] Example 1

[0070] This embodiment uses an electromagnetically driven or electrostatically driven single-axis MEMS micromirror as an example for illustration:

[0071] like Figure 3 As shown, the MEMS micromirror to be designed and fabricated in this embodiment can be mainly divided into a movable structure and a non-enclosed fixed frame 2. The movable structure includes a reflector 3, which is connected to the non-enclosed fixed frame 2 on both sides via torsion beams 4. The connection point between the torsion beams 4 and the non-enclosed fixed frame 2 is an anchor point 5. The movable structure is suspended within the non-enclosed fixed frame 2. When the non-enclosed fixed frame 2 is fixed, the movable structure can reciprocate around the torsion beams 4 under the application of an external driving force, thereby realizing the function of the MEMS micromirror. The non-enclosed fixed frame 2 is the chip's frame edge and the fixed base for all other structures. It is a rectangular frame with a notch 6. The notch 6 is located on the frame edge where the anchor point 5 is located, and its length is equal to the length of the other frame edge where the anchor point 5 is located. In other embodiments, the length of the notch 6 can be adjusted according to the actual size of the MEMS micromirror's reflective surface and the size of the laser spot in the application scenario.

[0072] The thickness of the torsion beam and movable structure can be the same as or thinner than the non-enclosed fixed frame 2. If it is thinner than the fixed frame, the torsion beam and movable structure can be thinned by wet etching or dry etching of the upper or lower surface.

[0073] The dicing paths of MEMS micromirror wafers are designed in appropriate X and Y axis directions, such as Figure 5 The black dashed lines in the diagram represent the cutting paths, resulting in a non-closed fixing frame 2 structure after the MEMS micromirror chip is cut. The "closed" shape of the closed fixing frame 02 is shown in the diagram. Figure 6 .

[0074] If at least one side of the torsion beam 4 and the movable structure 8 suspended within the non-enclosed fixed frame 2 is not coplanar with the non-enclosed fixed frame 2, but is recessed within the non-enclosed fixed frame 2 (see...) Figure 7 If the recessed surface 9 in the movable structure 8 is not required, then a specially designed and processed patterned dicing film is not needed. Simply attach the recessed side of the structure to the regular dicing film. In this case, the dicing film does not contact the recessed surface 9 in the movable structure 8, thus normal cutting, film expansion, and core extraction are sufficient. If the torsion beam suspended within the non-enclosed fixed frame 2 and the upper surface 81 and lower surface 82 of the movable structure both have partial areas coplanar with the non-enclosed fixed frame 2 (see...), Figure 8 If the process is not feasible, a specially designed and processed patterned dicing film is required to assist in cutting, expanding the film, and core extraction by following these steps.

[0075] The specific preparation method is as follows:

[0076] Combination Figures 9 to 12a , Figure 12b A dicing film is selected and fixed onto the dicing ring. The dicing film can be a UV-dissolving adhesive film, a thermally dissolving adhesive film, or other adhesive films whose viscosity can be adjusted by specific external conditions. The specific structure of the MEMS micromirror chip is projected onto the dicing film. The adhesive layer is retained at the projection areas of the non-enclosed fixing frame 2 and the chip-free areas of the wafer for chip fixation; this area is defined as adhesive region 11. Figure 9 and Figure 11 The adhesive layer on the projected areas of the movable structure and structural gaps is debonded until it is completely non-adhesive, and this area is defined as the debonding zone 12. Figure 12a and Figure 12b ), to make a patterned adhesive layer dicing film.

[0077] like Figure 10 As shown, the patterning of the adhesive layer on the dicing film can be achieved by photomask-assisted light-induced descaling or coating, by imprinting coating, by targeted heating descaling, or by attaching an additional patterned viscosity isolation film to the adhesive layer of the dicing film.

[0078] like Figure 12a and Figure 12b As shown, the MEMS micromirror wafer 10 is aligned and bonded to the patterned adhesive film. The alignment accuracy depends on the structural size of the MEMS micromirror chip and the dimensional accuracy of the patterned adhesive film. Generally, the accuracy requirement is not high, approximately ±0.2mm. During bonding, either the front side (reflective mirror surface) of the MEMS micromirror or the back side can be bonded to the scribe film. There are no special requirements, and appropriate fixtures can be selected and designed to assist in alignment and bonding as needed.

[0079] After the MEMS micromirror wafer 10 is attached and fixed on the dicing film, the chip is cut into a "C"-shaped frame according to the designed dicing path.

[0080] After cutting, the film is expanded until the spacing of the MEMS micromirror chip array on the wafer is increased to facilitate core extraction, forming a micromirror chip array with reasonable spacing between independent components.

[0081] Before core extraction, the entire cut and expanded wafer is desorbed until the viscosity is significantly reduced. The degree of reduction is set according to the actual needs.

[0082] Example 2

[0083] This embodiment uses a single-axis MEMS micromirror driven by either electromagnetic or electrostatic means as an example:

[0084] The MEMS micromirror designed and fabricated in this embodiment can be mainly divided into a movable structure and a fixed frame. The movable structure includes a reflector 3, which is connected to the fixed frame on both sides by torsion beams 4. The connection point between the torsion beams 4 and the fixed frame is an anchor point 5. The movable structure is suspended within the fixed frame. When the fixed frame is fixed, the movable structure can reciprocate around the torsion beams 4 under the application of an external driving force, thereby realizing the function of the MEMS micromirror. The fixed frame is the chip's frame edge and serves as the fixed base for all other structures. It is a rectangular frame with a notch 6. The notch 6 is located on the frame edge where the anchor point 5 is not located, and its length is equal to the length of the other frame edge where the anchor point 5 is not located. In other embodiments, the length of the notch 6 can be adjusted according to the actual size of the MEMS micromirror reflector 3 and the size of the laser spot in the application scenario.

[0085] The thickness of the torsion beam and movable structure can be the same as or thinner than the fixed frame. If it is thinner than the fixed frame, the torsion beam and movable structure can be thinned by wet etching or dry etching of the upper or lower surface.

[0086] The dicing channels of MEMS micromirror wafers are designed in appropriate X and Y axis directions, so that the MEMS micromirror chip is cut into an open "C" shape with a fixed frame, rather than a closed "closed" shape with a closed frame.

[0087] If at least one side of the torsion beam 4 and the movable structure 8 suspended within the non-enclosed fixed frame 2 is not coplanar with the non-enclosed fixed frame 2, but is recessed within the non-enclosed fixed frame 2 (see...) Figure 7 If the recessed surface 9 is not required, then a screen-printed additive layer 7 is not necessary. Simply attach the recessed side of the structure to the standard film, and proceed with normal cutting, film expansion, and core extraction. If the torsion beam suspended within the non-enclosed fixed frame 2 and the upper surface 81 and lower surface 82 of the movable structure both have portions coplanar with the non-enclosed fixed frame 2 (see...), then... Figure 8 If the wafer is to be screen-printed, an additive layer needs to be created on the wafer, and then the wafer is cut, expanded and cored using conventional dicing film following the steps below.

[0088] like Figure 13 As shown, a screen printing paste is selected, and a patterned screen-printed additive layer 7 with a thickness of 10-100 μm is fabricated on the non-enclosed fixing frame 2 of the MEMS micromirror wafer using screen printing. This ensures good adhesion between the screen printing paste and the non-enclosed fixing frame 2 of the MEMS micromirror wafer, and that the paste surface has a smooth surface. The screen-printed surface can be any side of the MEMS micromirror wafer, but the side with the larger printable area is preferred.

[0089] like Figure 14As shown, the MEMS micromirror wafer with the screen-printed additive layer 7 is bonded to the conventional film 13, so that the screen-printed additive layer 7 adheres to the conventional film 13, while the movable chip structure 8 does not contact or adhere to the conventional film 13 due to the presence of the screen-printed additive layer 7.

[0090] After the MEMS micromirror wafer is attached and fixed on the conventional dicing film 13, the chip is cut into a "C"-shaped frame according to the designed dicing path, rather than the conventional "closed" shape.

[0091] After cutting, the film is expanded until the spacing of the MEMS micromirror chip array on the wafer is increased to facilitate core extraction, forming a micromirror chip array with reasonable spacing between independent components.

[0092] Before core extraction, the entire cut and expanded wafer is desorbed until the viscosity is significantly reduced. The degree of reduction is set according to the actual needs.

Claims

1. A method for fabricating a MEMS micromirror to improve optical path obstruction, the MEMS micromirror comprising a fixed frame and a movable structure (8) located at the center of the fixed frame and connected to the fixed frame via a torsion beam (4), wherein the connection point between the torsion beam (4) and the fixed frame is defined as an anchor point (5); the fixed frame is formed during the wafer dicing stage of the MEMS micromirror, and a notch (6) is opened on the fixed frame, the notch (6) being located on the frame side where the anchor point is located, to ensure that during large-angle scanning, the emitted light is directly emitted from the notch (6); the fixed frame is a rectangular, circular, or other irregularly shaped frame; the length of the notch (6) is equal to the length of the frame side where the other non-anchor point is located; the torsion beam (4) and the movable structure (8) are located on the same side or opposite sides; the movable structure (8) comprises a plane mirror (3) and a driver, the plane mirror (3) and the driver being located on the same side or opposite sides; the thickness of the movable structure (8) is less than or equal to the thickness of the fixed frame; characterized in that, Includes the following steps: Step 1: Determine whether both the upper and lower surfaces of the movable structure (8) in the MEMS micromirror to be processed have a portion of their area coplanar with the fixed frame. If so, proceed to step 2. Otherwise, attach the side of the movable structure (8) that is concave to the plane of the fixed frame to the conventional film (13) and proceed to step 3. Step 2: Project the specific structure of the MEMS micromirror chip onto the scribe film. Retain the adhesive layer on the scribe film corresponding to the non-closed fixing frame area and the chip-free area of ​​the wafer to fix the chip. De-adhesive layer corresponding to the movable structure area and the structural gap area until it is completely non-adhesive to make a patterned adhesive layer scribe film. Align and bond the MEMS micromirror wafer with the patterned adhesive layer scribe film. Step 3: Cut the chip into a fixed frame shape according to the designed dicing path; Step 4: Expand the spacing of the MEMS micromirror chip array on the wafer through a film expansion process until it is easy to extract the core, forming a micromirror chip array with reasonable spacing between independent components. Step 5: After cutting and expanding the entire wafer, remove the adhesive until the viscosity decreases, and then extract the core.

2. The fabrication method for improving optical path obstruction of a MEMS micromirror according to claim 1, characterized in that: In step 2, the diced film is an adhesive film whose viscosity can be adjusted by applying specific external conditions.

3. The fabrication method for improving optical path obstruction of a MEMS micromirror according to claim 2, characterized in that: The adhesive film is a UV-dissolving adhesive film or a pyrolytic adhesive film.

4. The fabrication method for improving optical path obstruction of a MEMS micromirror according to claim 3, characterized in that: In step 2, the adhesive layer corresponding to the movable structural area and the structural gap area is debonded until it is completely non-adhesive, and a patterned adhesive layer scribe film is made. The debonding is specifically achieved by the following method: Photolithography with mask assistance is used to depolymerize the gel. Alternatively, it can be achieved through embossing and coating. Alternatively, it can be achieved through mold-assisted point heating and degumming; Alternatively, this can be achieved by attaching an additional layer of patterned viscosity isolation film to the dicing film adhesive layer.

5. The fabrication method for improving optical path obstruction of a MEMS micromirror according to claim 4, characterized in that: In step 2, when aligning and bonding the MEMS micromirror wafer with the scribe film of the patterned adhesive layer, the front side of the MEMS micromirror is attached to the scribe film of the patterned adhesive layer, or the back side of the MEMS micromirror is attached to the scribe film of the patterned adhesive layer.

6. A method for fabricating a MEMS micromirror to improve optical path obstruction, the MEMS micromirror comprising a fixed frame and a movable structure (8) located at the center of the fixed frame and connected to the fixed frame via a torsion beam (4), wherein the connection point between the torsion beam (4) and the fixed frame is defined as an anchor point (5); the fixed frame is formed during the wafer dicing stage of the MEMS micromirror, and a notch (6) is opened on the fixed frame, the notch (6) being located on the frame side where the anchor point is located, to ensure that during large-angle scanning, the emitted light is directly emitted from the notch (6); the fixed frame is a rectangular, circular, or other irregularly shaped frame; the length of the notch (6) is equal to the length of the frame side where the other non-anchor point is located; the torsion beam (4) and the movable structure (8) are located on the same side or opposite sides; the movable structure (8) comprises a plane mirror (3) and a driver, the plane mirror (3) and the driver being located on the same side or opposite sides; the thickness of the movable structure (8) is less than or equal to the thickness of the fixed frame; characterized in that, Includes the following steps: Step 1: Determine whether both the upper and lower surfaces of the movable structure (8) in the MEMS micromirror to be processed have a portion of their area coplanar with the fixed frame. If so, proceed to step 2. Otherwise, attach the side of the movable structure (8) that is concave to the plane of the fixed frame to the conventional film (13) and proceed to step 3. Step 2: A patterned additive layer is fabricated on the non-closed fixing frame and the chip-free area of ​​the MEMS micromirror wafer by screen printing. The MEMS micromirror wafer with the screen-printed additive layer (7) is bonded to the conventional film (13), so that the MEMS micromirror chip is adhered to the conventional film (13) through the screen-printed additive layer (7). The MEMS micromirror wafer part corresponding to the chip movable structure (8) will not contact or adhere to the conventional film (13) due to the presence of the screen-printed additive layer (7). Step 3: Cut the chip into a fixed frame shape according to the designed dicing path; Step 4: Expand the spacing of the MEMS micromirror chip array on the wafer through a film expansion process until it is easy to extract the core, forming a micromirror chip array with reasonable spacing between independent components. Step 5: After cutting and expanding the entire wafer, remove the adhesive until the viscosity decreases, and then extract the core.

7. The fabrication method for improving optical path obstruction of a MEMS micromirror according to claim 6, characterized in that, In step 2, the thickness of the screen-printed additive layer (7) is 10-500um.

8. The fabrication method for improving optical path obstruction of a MEMS micromirror according to claim 7, characterized in that, In step 2, the screen-printed addition layer (7) is located on the side of the MEMS micromirror wafer with a larger printable area.

Images