CN114077047A - MEMS micro-mirror with symmetrical folding elastic beam structure and manufacturing method thereof - Google Patents
MEMS micro-mirror with symmetrical folding elastic beam structure and manufacturing method thereof Download PDFInfo
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- CN114077047A CN114077047A CN202010843569.XA CN202010843569A CN114077047A CN 114077047 A CN114077047 A CN 114077047A CN 202010843569 A CN202010843569 A CN 202010843569A CN 114077047 A CN114077047 A CN 114077047A
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
- G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
- G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
- B81C1/0015—Cantilevers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00349—Creating layers of material on a substrate
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
- B81C1/00523—Etching material
Abstract
The MEMS micro-mirror comprises a frame, a movable micro-light reflector, a symmetrical folding elastic beam structure and a comb tooth structure, wherein the symmetrical folding elastic beam structure comprises a first folding elastic beam and a second folding elastic beam, the first folding elastic beam, the movable micro-light reflector and the second folding elastic beam are sequentially connected in a first direction, and the first folding elastic beam and the second folding elastic beam are symmetrically arranged relative to the movable micro-light reflector. The MEMS micro-mirror is manufactured by adopting the substrate with two device layers, the process flow can be simplified, the driving and reliability performance of the device can be improved, the symmetrical folding elastic beam structure has the characteristic of high symmetry relative to the movable micro-mirror, no torque can be generated when the movable micro-mirror is impacted or vibrated, the impact resistance or the vibration resistance of the MEMS micro-mirror is improved, and the reliability of the MEMS micro-mirror is improved.
Description
Technical Field
The invention belongs to the technical field of micro-electro-mechanical systems (MEMS), and relates to an MEMS micro-mirror with a symmetrical folding elastic beam structure and a manufacturing method thereof.
Background
MEMS micromirrors have been successfully applied to optical communication components such as Variable Optical Attenuators (VOAs), optical switches (switches), Tunable Filters (TFs), wavelength selectors (WSS), etc. due to their advantages of compact structure, high reliability, and low cost. In addition, the MEMS micro-mirror has a wide market application in the fields of laser scanning (such as laser radar), digital display (such as laser projection), and the like.
The electrostatic comb drive has the advantages of small power, good compatibility, small interference, small volume, mass production and the like, and becomes one of the main directions of the MEMS micro-mirror drive mode. However, in the environment of external impact or vibration, the performance (e.g., rotational stability) of the MEMS micro-mirror is affected to some extent, and particularly, the rotational performance and structural reliability of the two-axis MEMS micro-mirror are affected to different degrees in all directions.
Therefore, how to further improve the shock resistance or vibration resistance of the MEMS micro-mirror and improve the above-mentioned defects is a problem to be solved.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention is directed to a MEMS micro-mirror with a symmetrical folded elastic beam structure, which is used to solve the problem that the rotation performance of the MEMS micro-mirror is easily affected in the external impact or vibration environment.
To achieve the above and other related objects, the present invention provides a MEMS micromirror with a symmetrically folded elastic beam structure, comprising:
a frame;
a movable micro mirror positioned within the frame;
the symmetrical folding elastic beam structure is positioned in the frame and connected with the frame, the symmetrical folding elastic beam structure comprises a first folding elastic beam and a second folding elastic beam, the first folding elastic beam, the movable micro-light reflector and the second folding elastic beam are sequentially connected in a first direction, and the first folding elastic beam and the second folding elastic beam are symmetrically arranged relative to the movable micro-light reflector;
the comb tooth structure is positioned in the frame and connected with the frame and the movable micro-light reflector to drive the movable micro-light reflector to rotate, the comb tooth structure comprises an upper comb tooth structure and a lower comb tooth structure, the top surface of the upper comb tooth structure is higher than that of the lower comb tooth structure, and the projections of the upper comb tooth structure and the lower comb tooth structure on the horizontal plane are arranged in a staggered mode.
Optionally, the frame includes inner frame and outer frame, first folding elastic beam with the second folding elastic beam be located in the inner frame and with the internal frame is connected, the folding elastic beam structure of symmetry still includes third folding elastic beam and fourth folding elastic beam, third folding elastic beam with the fourth folding elastic beam all connect in outer frame with between the inner frame, third folding elastic beam movable little light reflector reaches the fourth folding elastic beam arranges in proper order in the second direction, just third folding elastic beam with the fourth folding elastic beam for movable little light reflector symmetry sets up, the second direction with first direction is perpendicular.
Optionally, the first folded elastic beam and the second folded elastic beam are the same in shape and size; the third folding elastic beam and the fourth folding elastic beam are the same in shape and size; the first folding elastic beam, the second folding elastic beam, the third folding elastic beam and the fourth folding elastic beam are axisymmetric patterns, the first folding elastic beam and the symmetry axis of the second folding elastic beam are overlapped and combined in the first direction, and the third folding elastic beam and the symmetry axis of the fourth folding elastic beam are overlapped and combined in the second direction.
Optionally, the first, second, third, or fourth folded elastic beams include two independently disposed folded beams, and the first or second folded elastic beam is connected to the movable micro-light reflector through two anchor points and connected to the frame through another two anchor points; the third folding elastic beam or the fourth folding elastic beam is connected with the inner frame through two anchor points and is connected with the outer frame through another two anchor points.
Optionally, the first, second, third, or fourth folded elastic beams are composite folded beams, and the first or second folded elastic beams are connected to the movable micro-light reflector through one anchor point and connected to the frame through another two anchor points; the third folding elastic beam or the fourth folding elastic beam is connected with the inner frame through one anchor point and is connected with the outer frame through the other two anchor points; or the first folding elastic beam or the second folding elastic beam is connected with the movable micro-light reflector through two anchor points and is connected with the frame through the other anchor point; the third folding elastic beam or the fourth folding elastic beam is connected with the inner frame through two anchor points and is connected with the outer frame through another anchor point.
Optionally, the MEMS micromirror with the symmetric folding elastic beam structure further includes a substrate, the substrate is located below the frame, the movable micromirror, the symmetric folding elastic beam structure, and the comb structure, and a groove structure is provided in the substrate to provide a movement space for the movable micromirror and the symmetric folding elastic beam structure.
Optionally, the groove structure is a groove with a closed bottom, or the groove structure is a through groove with an upper opening and a lower opening.
Optionally, the MEMS micro-mirror further comprises a metal reflective layer on a surface of the movable micro-mirror.
Optionally, the MEMS micro-mirror further includes an upper comb electrode and a lower comb electrode, and the upper comb electrode and the lower comb electrode are electrically connected to the upper comb and the lower comb, respectively.
Optionally, the thickness of the symmetrically folded elastic beam structure is the same as the thickness of the upper comb tooth structure or the lower comb tooth structure, or the thickness of the symmetrically folded elastic beam structure is the same as the total thickness of the comb tooth structures.
The invention also provides a manufacturing method of the MEMS micro-mirror with the symmetrical folding elastic beam structure, which comprises the following steps:
providing a double-device-layer substrate, wherein the double-device-layer substrate comprises a first device layer, a first insulating layer, a second device layer, a second insulating layer and a substrate layer which are sequentially stacked;
etching the first device layer and the first insulating layer to form a lower comb tooth structure in the first device layer;
providing a substrate, forming a groove structure in the substrate, wherein the groove structure is provided with an opening on the front surface of the substrate;
bonding one surface of the double-device-layer substrate, which is provided with the first device layer, with the front surface of the substrate to form a bonded body structure, wherein the lower comb tooth structure is positioned above the groove structure;
removing the base layer to expose the second insulating layer;
etching the second insulating layer and the second device layer to obtain an upper comb tooth structure, a movable micro-light reflector and a symmetrical folding elastic beam structure in the second device layer, wherein the upper comb tooth structure, the movable micro-light reflector and the symmetrical folding elastic beam structure are positioned above the groove structure, the symmetrical folding elastic beam structure comprises a first folding elastic beam and a second folding elastic beam, the first folding elastic beam, the movable micro-light reflector and the second folding elastic beam are sequentially connected in a first direction, the first folding elastic beam and the second folding elastic beam are symmetrically arranged relative to the movable micro-light reflector, and the projections of the upper comb tooth structure and the lower comb tooth structure on a horizontal plane are staggered;
and removing the second insulating layer and removing the part of the first insulating layer on the surface of the lower comb tooth structure.
Optionally, after the first device layer and the second device layer are etched, the parts of the first device layer and the second device layer, which are positioned at the periphery of the movable micro-light reflector, form an inner frame and an outer frame, the first and second folded elastic beams are positioned inside the inner frame and connected with the inner frame, the symmetrical folding elastic beam structure also comprises a third folding elastic beam and a fourth folding elastic beam, the third folding elastic beam and the fourth folding elastic beam are both connected between the outer frame and the inner frame, the third folding elastic beam, the movable micro-light reflector and the fourth folding elastic beam are arranged in sequence in a second direction, and the third folding elastic beam and the fourth folding elastic beam are symmetrically arranged relative to the movable micro-light reflector, and the second direction is vertical to the first direction.
Optionally, the groove structure is a groove with a closed bottom, or the groove structure is a through groove with an upper opening and a lower opening.
As mentioned above, the method for manufacturing the MEMS micro-mirror with the symmetrical folding elastic beam structure adopts the substrate with double device layers (such as the SOI low-resistance silicon wafer with double device layers) to manufacture the MEMS micro-mirror, so that the process flow can be simplified, and the driving and reliability performance of the device can be improved. The symmetrical folding elastic beam structure has the characteristic of high symmetry about the movable micro-mirror reflector, and can not generate any torque when being impacted or vibrated, so that the impact resistance or vibration resistance of the MEMS micro-mirror is further improved, and the reliability of the MEMS micro-mirror is improved. In addition, the shape, the thickness and the like of the symmetrical folding elastic beam structure can be flexibly selected according to design requirements, the flexibility is high, and the application range is wider.
Drawings
FIG. 1 is a top view of a MEMS micro-mirror according to one embodiment.
FIG. 2 is a cross-sectional view taken along line A-A' of the structure shown in FIG. 1.
Fig. 3 shows an enlarged view of the area indicated by the dashed box in fig. 1.
Fig. 4 is a plan view showing a structure of the first folded elastic beam in another embodiment.
FIG. 5 is a top view of a MEMS micro-mirror according to a second embodiment.
FIG. 6 provides a schematic illustration of a two device layer substrate.
FIG. 7 is a schematic diagram illustrating the formation of a lower comb structure on the first device layer.
Fig. 8 shows a schematic view of forming a trench structure in the substrate.
Fig. 9 is a schematic diagram showing that the surface of the double-device-layer base with the first device layer is bonded with the front surface of the substrate to form a bonding body structure.
Fig. 10 is a schematic view showing the removal of the base layer.
Fig. 11 shows a schematic diagram of etching an upper comb structure, a movable micromirror and a symmetrically folded elastic beam structure in the second device layer.
FIG. 12 is a schematic diagram showing the removal of the second insulating layer and the removal of the portion of the first insulating layer on the surface of the lower comb tooth structure.
Fig. 13 is a schematic view showing the formation of the upper comb-tooth electrode and the lower comb-tooth electrode.
FIG. 14 is a schematic diagram of a metal reflective layer formed on the surface of the movable micro reflector.
Description of the element reference numerals
1 frame
101 inner frame
102 outer frame
2 substrate
3 Movable micro-light reflector
4 first folding elastic beam
5 second folding elastic beam
6 comb tooth structure
7 lower comb tooth structure
8 metal reflective layer
9 comb electrode
10 lower comb electrode
11 third folding elastic beam
12 fourth folding elastic beam
13 first device layer
14 first insulating layer
15 second device layer
16 second insulating layer
17 base layer
18-groove structure
19 front side insulating layer
20 back side insulating layer
21 electrode lead slot
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Please refer to fig. 1 to 13. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
Example one
In the present embodiment, a single-axis MEMS micro-mirror with a symmetric folding elastic beam structure is provided, please refer to fig. 1 and fig. 2, wherein fig. 1 is a top view of the MEMS micro-mirror, fig. 2 is a cross-sectional view of the structure shown in fig. 1 along the direction a-a', the MEMS micro-mirror includes a frame 1, a movable micro-light reflector 3, a symmetric folding elastic beam structure, and a comb structure, wherein the movable micro-light reflector 3 is located in the frame 1; the symmetrical folding elastic beam structure is positioned in the frame 1 and connected with the frame 1, the symmetrical folding elastic beam structure comprises a first folding elastic beam 4 and a second folding elastic beam 5, the first folding elastic beam 4, the movable micro-light reflector 3 and the second folding elastic beam 5 are sequentially connected in a first direction X, and the first folding elastic beam 4 and the second folding elastic beam 5 are symmetrically arranged relative to the movable micro-light reflector 3; the comb tooth structure is positioned in the frame 1 and connected with the frame 1 and the movable micro-light reflector 3 to drive the movable micro-light reflector 3 to rotate, the comb tooth structure comprises an upper comb tooth structure 6 and a lower comb tooth structure 7, the top surface of the upper comb tooth structure 6 is higher than the top surface of the lower comb tooth structure 7, and the projections of the upper comb tooth structure 6 and the lower comb tooth structure 7 on the horizontal plane are arranged in a staggered mode.
As an example, the upper comb tooth structure 6 is connected to the movable micromirror 3, and the lower comb tooth structure 7 is connected to the frame 1. In other embodiments, the upper comb structure 6 may be connected to the frame 1, and the lower comb structure 7 may be connected to the movable micro-light reflector 3, which should not unduly limit the scope of the present invention.
As an example, the frame 1 may adopt a single-layer film structure or a multi-layer film structure, including but not limited to one or more of a silicon layer and a silicon oxide layer.
As an example, the MEMS micromirror with the symmetric folding elastic beam structure further comprises a substrate 2, the substrate 2 is located under the frame 1, the movable micromirror 3, the symmetric folding elastic beam structure and the comb tooth structure, and a slot structure 18 is provided in the substrate 2 to provide a motion space for the movable micromirror 3 and the symmetric folding elastic beam structure. The groove structure 18 may be a groove with a closed bottom, or may be a through groove with an upper opening and a lower opening.
Specifically, the first folded elastic beam 4 and the second folded elastic beam 5 achieve the elasticity of the structure by folding, where folding refers to bending the structure back and forth at least once.
As an example, the first folded elastic beam 4 and the second folded elastic beam 5 have the same shape and the same size. Preferably, the first folded elastic beam 4 and the second folded elastic beam 5 are both in an axisymmetric pattern, and the symmetry axes of the first folded elastic beam 4 and the second folded elastic beam 5 are overlapped in the first direction X.
Referring to fig. 3, which is an enlarged view of the area indicated by the dashed line frame in fig. 1, it can be seen that the movable micromirror 3 has a U-shaped wing, the main body of the first foldable elastic beam 4 is located in the space enclosed by the U-shaped wing, and the upper comb-tooth structure 6 is connected to the outer sidewall of the U-shaped wing. Of course, in other embodiments, the shape of the connecting portion of the movable micro light reflector 3 and the folding elastic beam and the comb structure can be adjusted according to the requirement, and the protection scope of the present invention should not be limited too much.
As an example, the first folded elastic beam 4 or the second folded elastic beam 5 comprises two separately arranged folded beams, e.g. two separate S-shaped structures. The first folding elastic beam 4 or the second folding elastic beam 5 is connected with the movable micro-light reflector 3 through two anchor points and is connected with the frame 1 through the other two anchor points.
Referring to fig. 4, a plan view of the first foldable elastic beam 4 is shown, in another embodiment, in this embodiment, the first foldable elastic beam 4 or the second foldable elastic beam 5 is a composite foldable beam, for example, two S-shaped structures sharing one side, and the first foldable elastic beam 4 or the second foldable elastic beam 5 is connected to the movable micro-light reflector 3 through an anchor point and is connected to the frame 1 through another two anchor points. In other embodiments, the first folded elastic beam 4 or the second folded elastic beam 5 may also be connected to the movable micro-mirror 3 by two anchor points and to the frame 1 by another anchor point.
It should be noted that in other embodiments, the folding patterns of the first folded elastic beam 4 and the second folded elastic beam 5 can also be adjusted according to the needs, and the protection scope of the present invention should not be limited excessively herein.
As an example, the MEMS micro mirror further comprises a metal reflective layer 8, and the metal reflective layer 8 is located on the surface of the movable micro mirror 3.
As an example, the MEMS micro-mirror further includes an upper comb-tooth electrode 9 and a lower comb-tooth electrode 10, and the upper comb-tooth electrode 9 and the lower comb-tooth electrode 10 are electrically connected to the upper comb-tooth structure 6 and the lower comb-tooth structure 7, respectively, for implementing an electrostatic driving function of the comb-tooth structure. The specific positions of the upper comb-teeth electrode 9 and the lower comb-teeth electrode 10 can be adjusted according to the needs, and the protection scope of the present invention should not be limited too much here.
As an example, the thickness of the symmetrically folded elastic beam structure may be the same as the thickness of the upper comb tooth structure 6 or the lower comb tooth structure 7, or may be the same as the total thickness of the comb tooth structure.
In the MEMS micro-mirror with the symmetrical folding elastic beam structure of the present embodiment, the symmetrical folding elastic beam structure has a highly symmetrical feature with respect to the movable micro-mirror, and does not generate any torque when being impacted or vibrated, thereby further improving the impact resistance or vibration resistance of the MEMS micro-mirror, and improving the reliability of the MEMS micro-mirror. In addition, the shape, the thickness and the like of the symmetrical folding elastic beam structure can be flexibly selected according to design requirements, the flexibility is high, and the application range is wider.
Example two
The present embodiment uses substantially the same technical solution as the first embodiment, except that the first embodiment uses a single-axis MEMS micromirror with a symmetric folding elastic beam structure, and the present embodiment uses a dual-axis MEMS micromirror with a symmetric folding elastic beam structure.
Referring to fig. 5, which is a top view of the biaxial MEMS micromirror with the symmetric folding elastic beam structure, relative to the first embodiment, the frame 1 in this embodiment comprises an inner frame 101 and an outer frame 102, the first and second folded resilient beams 4 and 5 are located inside and connected to the inner frame, the symmetrically folded elastic beam structure further comprises a third folded elastic beam 11 and a fourth folded elastic beam 12, the third folding elastic beam 11 and the fourth folding elastic beam 12 are connected between the outer frame 102 and the inner frame 101, the third folding elastic beam 11, the movable micro-light reflector 3 and the fourth folding elastic beam 12 are arranged in sequence in the second direction Y, the third folding elastic beam 11 and the fourth folding elastic beam 12 are symmetrically arranged relative to the movable micro-light reflector 3, and the second direction Y is perpendicular to the first direction X.
As an example, the first folded elastic beam 4 and the second folded elastic beam 5 have the same shape and the same size; the third folding elastic beam 11 and the fourth folding elastic beam 12 have the same shape and the same size. Preferably, the first folding elastic beam 4, the second folding elastic beam 5, the third folding elastic beam 11 and the fourth folding elastic beam 12 are axisymmetric patterns, the first folding elastic beam 4 and the second folding elastic beam 5 have symmetrical axes overlapping and are in the first direction X, the third folding elastic beam 11 and the fourth folding elastic beam 12 have symmetrical axes overlapping and are in the second direction Y.
EXAMPLE III
The embodiment provides a preparation method of a symmetrical folding elastic beam structure MEMS micro-mirror, which realizes the design and the manufacture of a single-axis MEMS micro-mirror of a symmetrical folding elastic beam structure by using a standard MEMS process, has stable manufacturing process, can be suitable for large-scale production, can flexibly select the shape, the size and the like of a symmetrical folding elastic beam according to design requirements, and has high flexibility and wider application range.
Referring to fig. 6, step S1 is executed: a dual device layer substrate is provided, which includes a first device layer 13, a first insulating layer 14, a second device layer 15, a second insulating layer 16, and a base layer 17 stacked in this order.
As an example, the material of the first device layer 13 and the second device layer 15 includes, but is not limited to, silicon, the material of the first insulating layer 14 and the second insulating layer 16 includes, but is not limited to, silicon oxide, and the material of the base layer 17 includes, but is not limited to, silicon. In this embodiment, the dual-device-layer substrate preferably adopts a dual-device-layer low-resistance SOI silicon wafer, and sequentially includes, from bottom to top, a first silicon device layer, a first silicon oxide layer, a second silicon device layer, a second silicon oxide layer, and a silicon substrate layer.
Referring to fig. 7, step S2 is executed: and etching the first device layer 13 and the first insulating layer 14 to form a lower comb tooth structure 7 in the first device layer 13.
Specifically, a photolithography process is performed to obtain a patterned mask layer on the surface of the first device layer 13, the first device layer 13 is etched to the surface of the first insulating layer 14, the first insulating layer 14 is etched to obtain the lower comb tooth structure 7, and the lower comb tooth structure 7 includes a plurality of lower comb teeth.
Referring to fig. 8, step S3 is executed: providing a substrate 2, forming a trench structure 18 in the substrate 2, the trench structure 18 having an opening at a front side of the substrate 2.
As an example, the front side of the substrate 2 is provided with a front side insulating layer 19.
As an example, the substrate 2 is a double-polished silicon wafer, and the front-side insulation layer 19 is formed by oxidizing the surface of the substrate 2, in this embodiment, the back side of the substrate 2 is also oxidized during the oxidation process to form the back-side insulation layer 20. And subsequently, further adopting photoetching and etching processes to form the groove structure 18, wherein the groove structure 18 can not penetrate through the back surface of the substrate 2 or can penetrate through the back surface of the substrate 2.
Specifically, the groove structure 18 is used to provide a rotation space for the movable portion of the micromirror, the etching depth is the size of the rotation gap of the movable portion of the micromirror, the etching depth can be flexibly adjusted according to the size of the rotation space required by the movable portion of the micromirror, and even the entire substrate silicon wafer is etched to form a through groove.
Referring to fig. 9, step S4 is executed: and bonding the surface of the double-device-layer substrate, which is provided with the first device layer 13, with the front surface of the substrate 2 to form a bonded body structure, wherein the lower comb tooth structure 7 is positioned above the groove structure 18.
Specifically, the surface of the double-device-layer substrate having the first device layer 13 is aligned and bonded with the surface of the front-side insulating layer 19 of the substrate 2, and the movable micro-light reflector 3 formed subsequently moves in the groove structure 18 of the substrate 2.
Referring to fig. 10, step S5 is executed: the base layer 17 is removed to expose the second insulating layer 16.
Specifically, the substrate layer 17 of the bonding body structure is removed by using a dry etching process, a wet etching process, or a Chemical Mechanical Polishing (CMP) process, so as to expose the second insulating layer 16.
Referring to fig. 11, step S6 is executed: etching the second insulating layer 16 and the second device layer 15 to obtain an upper comb structure 6, a movable micro-light reflector 3 and a symmetrical folding elastic beam structure in the second device layer 15, wherein the upper comb structure 6, the movable micro-light reflector 3 and the symmetrical folding elastic beam structure are located above the groove structure 18, the symmetrical folding elastic beam structure comprises a first folding elastic beam 4 and a second folding elastic beam 5 (see fig. 1), the first folding elastic beam 4, the movable micro-light reflector 3 and the second folding elastic beam 5 are sequentially connected in a first direction X, the first folding elastic beam 4 and the second folding elastic beam 5 are symmetrically arranged relative to the movable micro-light reflector 3, and projections of the upper comb structure 6 and the lower comb structure 7 on a horizontal plane are arranged in a staggered manner.
Specifically, the second insulating layer 16 is patterned through photolithography and etching processes, and the patterned second insulating layer 16 is used as an etching mask to etch the second device layer 15, so as to obtain the upper comb structure 6, where the upper comb structure 6 includes a plurality of upper comb teeth. Wherein, go up broach structure 6 with broach structure 7 need carry out the high accuracy and aim at (ensure to stagger preset distance) down to guarantee the uniformity in broach structure 6 and 7 electric capacity clearances of lower broach structure.
As an example, the electrode lead grooves 21 of the lower comb-tooth structure 7 are also formed in the second device layer 15 at the same time as the upper comb-tooth structure 6 is formed.
Specifically, the first folded elastic beam 4 and the second folded elastic beam 5 achieve the elasticity of the structure by folding, where folding refers to bending the structure back and forth at least once.
As an example, the first folded elastic beam 4 and the second folded elastic beam 5 have the same shape and the same size. Preferably, the first folded elastic beam 4 and the second folded elastic beam 5 are both in an axisymmetric pattern, and the symmetry axes of the first folded elastic beam 4 and the second folded elastic beam 5 are overlapped in the first direction X.
As an example, please refer to fig. 1, which shows a planar layout of the movable micro mirror 3 and the symmetrically folded elastic beam structure, and refer to fig. 3, which shows an enlarged view of an area shown by a dashed line frame in fig. 1, it can be seen that the movable micro mirror 3 has a U-shaped side wing, a main body of the first folded elastic beam 4 is located in a space surrounded by the U-shaped side wing, and the upper comb tooth structure 6 may be connected to an outer sidewall of the U-shaped side wing or connected to a sidewall of a circular portion of the movable micro mirror 3. Of course, in other embodiments, the shape of the connecting portion of the movable micro light reflector 3 and the folding elastic beam and the comb structure can be adjusted according to the requirement, and the protection scope of the present invention should not be limited too much.
As an example, the first folded elastic beam 4 or the second folded elastic beam 5 comprises two separately arranged folded beams, e.g. two separate S-shaped structures. The first folding elastic beam 4 or the second folding elastic beam 5 is connected with the movable micro-light reflector 3 through two anchor points and is connected with the frame 1 through the other two anchor points.
Referring to fig. 4, a plan view of the first folded elastic beam 4 is shown in another embodiment, in which the first folded elastic beam 4 or the second folded elastic beam 5 is a composite folded beam, such as two S-shaped structures sharing one side. The first folding elastic beam 4 or the second folding elastic beam 5 is connected with the movable micro-light reflector 3 through an anchor point and is connected with the frame 1 through another two anchor points. In other embodiments, the first folded elastic beam 4 or the second folded elastic beam 5 may also be connected to the movable micro-mirror 3 by two anchor points and to the frame 1 by another anchor point.
It should be noted that in other embodiments, the folding patterns of the first folded elastic beam 4 and the second folded elastic beam 5 can also be adjusted according to the needs, and the protection scope of the present invention should not be limited excessively herein.
Referring to fig. 12, step S7 is executed: and removing the second insulating layer 16 and removing the part of the first insulating layer 14 on the surface of the lower comb tooth structure 7.
Specifically, the second insulating layer and the first insulating layer are removed by a dry etching process or a hydrofluoric acid (HF) etching process.
Referring to fig. 13, step S8 is executed: and forming an upper comb-tooth electrode 9 and a lower comb-tooth electrode 10 by sputtering or other suitable deposition process, wherein the upper comb-tooth electrode 9 is positioned on the surface of the second device layer 15, and the lower comb-tooth electrode 10 is positioned in the electrode lead groove 21 and on the surface of the first device layer 13.
Specifically, the upper comb-teeth electrode 9 is located in a lead region of the upper comb-teeth structure 6, and the specific position of the lead region can be adjusted as required. The upper comb-teeth electrode 9 and the lower comb-teeth electrode 10 are used for wire bonding, the thickness of the upper comb-teeth electrode and the lower comb-teeth electrode can be flexibly selected according to needs, and the material of the upper comb-teeth electrode and the lower comb-teeth electrode includes, but is not limited to, titanium or aluminum.
Referring to fig. 14, step S9 is executed: a metal reflective layer 8 is formed on the surface of the movable micromirror 3 by sputtering or other suitable deposition process.
Specifically, the metal reflective layer 8 is used for reflecting light, and the thickness thereof can be flexibly selected according to the requirement, and the material thereof includes, but is not limited to, titanium or aluminum.
Therefore, the single-axis MEMS micro-mirror with the symmetrical folding elastic beam structure is manufactured, the process flow can be simplified by the method of the embodiment with the substrate of the double device layers, and the driving and reliability performance of the device can be improved. The symmetrical folding elastic beam has the characteristic of high symmetry about the movable micro-mirror reflector, and can not generate any torque when being impacted or vibrated, so that the impact resistance or the vibration resistance of the MEMS micro-mirror is further improved, and the reliability of the MEMS micro-mirror is improved. In addition, the shape, the thickness and the like of the symmetrical folding elastic beam can be flexibly selected according to design requirements, the flexibility is high, and the application range is wider.
Example four
The present embodiment and the third embodiment adopt substantially the same technical solutions, except that the uniaxial MEMS micromirror with the symmetric folding elastic beam structure is fabricated in the third embodiment, and the biaxial MEMS micromirror with the symmetric folding elastic beam structure is fabricated in the present embodiment.
Specifically, compared to the third embodiment, in this embodiment, after the first device layer and the second device layer are etched, the portions of the first device layer and the second device layer, which are located at the periphery of the movable micro-mirror, form an inner frame and an outer frame, the first folding elastic beam and the second folding elastic beam are located in the inner frame and connected to the inner frame, the symmetric folding elastic beam structure further includes a third folding elastic beam and a fourth folding elastic beam, the third folding elastic beam and the fourth folding elastic beam are both connected between the outer frame and the inner frame, the third folding elastic beam, the movable micro-mirror and the fourth folding elastic beam are sequentially arranged in the second direction, and the third folding elastic beam and the fourth folding elastic beam are symmetrically arranged with respect to the movable micro-mirror, the second direction is perpendicular to the first direction.
As an example, the first folded elastic beam 4 and the second folded elastic beam 5 have the same shape and the same size; the third folding elastic beam 11 and the fourth folding elastic beam 12 have the same shape and the same size. Preferably, the first folding elastic beam 4, the second folding elastic beam 5, the third folding elastic beam 11 and the fourth folding elastic beam 12 are axisymmetric patterns, the first folding elastic beam 4 and the second folding elastic beam 5 have symmetrical axes overlapping and are in the first direction X, the third folding elastic beam 11 and the fourth folding elastic beam 12 have symmetrical axes overlapping and are in the second direction Y.
In summary, the method for fabricating the MEMS micro-mirror with the symmetric folding elastic beam structure of the present invention employs a substrate with two device layers (e.g., a SOI low-resistance silicon wafer with two device layers), which can simplify the process flow and improve the driving and reliability performance of the device. The symmetrical folding elastic beam structure has the characteristic of high symmetry about the movable micro-mirror reflector, and can not generate any torque when being impacted or vibrated, so that the impact resistance or vibration resistance of the MEMS micro-mirror is further improved, and the reliability of the MEMS micro-mirror is improved. In addition, the shape, the thickness and the like of the symmetrical folding elastic beam structure can be flexibly selected according to design requirements, the flexibility is high, and the application range is wider. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (13)
1. A MEMS micromirror of a symmetrically folded elastic beam structure, comprising:
a frame;
a movable micro mirror positioned within the frame;
the symmetrical folding elastic beam structure is positioned in the frame and connected with the frame, the symmetrical folding elastic beam structure comprises a first folding elastic beam and a second folding elastic beam, the first folding elastic beam, the movable micro-light reflector and the second folding elastic beam are sequentially connected in a first direction, and the first folding elastic beam and the second folding elastic beam are symmetrically arranged relative to the movable micro-light reflector;
the comb tooth structure is positioned in the frame and connected with the frame and the movable micro-light reflector to drive the movable micro-light reflector to rotate, the comb tooth structure comprises an upper comb tooth structure and a lower comb tooth structure, the top surface of the upper comb tooth structure is higher than that of the lower comb tooth structure, and the projections of the upper comb tooth structure and the lower comb tooth structure on the horizontal plane are arranged in a staggered mode.
2. The MEMS micromirror of symmetric folded elastic beam structure according to claim 1, wherein: the frame includes inner frame and outer frame, first folding elastic beam with the second folding elastic beam be located in the inner frame and with the internal frame is connected, the folding elastic beam structure of symmetry still includes third folding elastic beam and fourth folding elastic beam, third folding elastic beam with the fourth folding elastic beam all connect in outer frame with between the inner frame, third folding elastic beam movable little light reflex mirror reaches the fourth folding elastic beam arranges in proper order in the second direction, just third folding elastic beam with the fourth folding elastic beam for movable little light reflex mirror symmetry sets up, the second direction with first direction is perpendicular.
3. The MEMS micromirror of symmetric folded elastic beam structure of claim 2, wherein: the first folding elastic beam and the second folding elastic beam are the same in shape and size; the third folding elastic beam and the fourth folding elastic beam are the same in shape and size; the first folding elastic beam, the second folding elastic beam, the third folding elastic beam and the fourth folding elastic beam are axisymmetric patterns, the first folding elastic beam and the symmetry axis of the second folding elastic beam are overlapped and combined in the first direction, and the third folding elastic beam and the symmetry axis of the fourth folding elastic beam are overlapped and combined in the second direction.
4. The MEMS micromirror of symmetric folded elastic beam structure of claim 2, wherein: the first folding elastic beam, the second folding elastic beam, the third folding elastic beam or the fourth folding elastic beam comprises two independently arranged folding beams, and the first folding elastic beam or the second folding elastic beam is connected with the movable micro-light reflector through two anchor points and is connected with the frame through the other two anchor points; the third folding elastic beam or the fourth folding elastic beam is connected with the inner frame through two anchor points and is connected with the outer frame through another two anchor points.
5. The MEMS micromirror of symmetric folded elastic beam structure of claim 2, wherein: the first folding elastic beam, the second folding elastic beam, the third folding elastic beam or the fourth folding elastic beam adopt composite folding beams, and the first folding elastic beam or the second folding elastic beam is connected with the movable micro-light reflector through one anchor point and is connected with the frame through the other two anchor points; the third folding elastic beam or the fourth folding elastic beam is connected with the inner frame through one anchor point and is connected with the outer frame through the other two anchor points; or the first folding elastic beam or the second folding elastic beam is connected with the movable micro-light reflector through two anchor points and is connected with the frame through the other anchor point; the third folding elastic beam or the fourth folding elastic beam is connected with the inner frame through two anchor points and is connected with the outer frame through another anchor point.
6. The MEMS micromirror of symmetric folded elastic beam structure according to claim 1 or 2, wherein: the MEMS micro-mirror with the symmetrical folding elastic beam structure also comprises a substrate, wherein the substrate is positioned below the frame, the movable micro-light reflector, the symmetrical folding elastic beam structure and the comb tooth structure, and a groove structure is arranged in the substrate to provide a movement space for the movable micro-light reflector and the symmetrical folding elastic beam structure.
7. The MEMS micromirror of symmetric folded elastic beam structure of claim 6, wherein: the groove structure is a groove with a closed bottom, or the groove structure is a through groove with an upper opening and a lower opening.
8. The MEMS micromirror of symmetric folded elastic beam structure according to claim 1 or 2, wherein: the MEMS micro-mirror further comprises a metal reflecting layer, and the metal reflecting layer is positioned on the surface of the movable micro-mirror.
9. The MEMS micromirror of symmetric folded elastic beam structure according to claim 1 or 2, wherein: the MEMS micro-mirror further comprises an upper comb electrode and a lower comb electrode, wherein the upper comb electrode and the lower comb electrode are respectively and electrically connected with the upper comb and the lower comb.
10. The MEMS micromirror of symmetric folded elastic beam structure according to claim 1 or 2, wherein: the thickness of the symmetrical folding elastic beam structure is the same as that of the upper comb tooth structure or the lower comb tooth structure, or the thickness of the symmetrical folding elastic beam structure is the same as the total thickness of the comb tooth structures.
11. A manufacturing method of a MEMS micro-mirror with a symmetrical folding elastic beam structure is characterized by comprising the following steps:
providing a double-device-layer substrate, wherein the double-device-layer substrate comprises a first device layer, a first insulating layer, a second device layer, a second insulating layer and a substrate layer which are sequentially stacked;
etching the first device layer and the first insulating layer to form a lower comb tooth structure in the first device layer;
providing a substrate, forming a groove structure in the substrate, wherein the groove structure is provided with an opening on the front surface of the substrate;
bonding one surface of the double-device-layer substrate, which is provided with the first device layer, with the front surface of the substrate to form a bonded body structure, wherein the lower comb tooth structure is positioned above the groove structure;
removing the base layer to expose the second insulating layer;
etching the second insulating layer and the second device layer to obtain an upper comb tooth structure, a movable micro-light reflector and a symmetrical folding elastic beam structure in the second device layer, wherein the upper comb tooth structure, the movable micro-light reflector and the symmetrical folding elastic beam structure are positioned above the groove structure, the symmetrical folding elastic beam structure comprises a first folding elastic beam and a second folding elastic beam, the first folding elastic beam, the movable micro-light reflector and the second folding elastic beam are sequentially connected in a first direction, the first folding elastic beam and the second folding elastic beam are symmetrically arranged relative to the movable micro-light reflector, and the projections of the upper comb tooth structure and the lower comb tooth structure on a horizontal plane are staggered;
and removing the second insulating layer and removing the part of the first insulating layer on the surface of the lower comb tooth structure.
12. The method of claim 11, wherein the MEMS micromirror has a symmetrical folded elastic beam structure, further comprising: after the first device layer and the second device layer are etched, the parts of the first device layer and the second device layer, which are positioned at the periphery of the movable micro-light reflector, form an inner frame and an outer frame, the first and second folded elastic beams are positioned inside the inner frame and connected with the inner frame, the symmetrical folding elastic beam structure also comprises a third folding elastic beam and a fourth folding elastic beam, the third folding elastic beam and the fourth folding elastic beam are both connected between the outer frame and the inner frame, the third folding elastic beam, the movable micro-light reflector and the fourth folding elastic beam are arranged in sequence in a second direction, and the third folding elastic beam and the fourth folding elastic beam are symmetrically arranged relative to the movable micro-light reflector, and the second direction is vertical to the first direction.
13. The method for fabricating a MEMS micromirror of symmetric folded elastic beam structure according to claim 11 or 12, wherein: the groove structure is a groove with a closed bottom, or the groove structure is a through groove with an upper opening and a lower opening.
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