CN113448080A

CN113448080A - MEMS galvanometer and manufacturing method thereof

Info

Publication number: CN113448080A
Application number: CN202111017550.0A
Authority: CN
Inventors: 王子栋; 程传同
Original assignee: Beijing Zhongke Haixin Technology Co ltd
Current assignee: Beijing Zhongke Haixin Technology Co ltd
Priority date: 2021-09-01
Filing date: 2021-09-01
Publication date: 2021-09-28

Abstract

The present disclosure provides an MEMS galvanometer and a method of making the same. The MEMS galvanometer includes: the mirror vibration part, the outer frame, the rotating shaft part connected between the mirror vibration part and the outer frame, and the hydrophobic membrane. Wherein, the hydrophobic membrane covers the surface of the rotating shaft part at least. The method comprises the following steps: providing a base layer; a galvanometer part of the MEMS galvanometer, an outer frame and a rotating shaft part connected between the galvanometer part and the outer frame are formed in the substrate layer; a hydrophobic film is formed on at least the outer surface of the rotating shaft. Some embodiments of the present disclosure provide MEMS mirrors with good fatigue resistance.

Description

MEMS galvanometer and manufacturing method thereof

Technical Field

The disclosure relates to the technical field of micro electro mechanical systems, in particular to an MEMS galvanometer and a manufacturing method thereof.

Background

Micro-Electro-Mechanical systems (MEMS) refers to a sensor, an actuator or a Micro-System with dimensions on the millimeter scale or smaller.

An MEMS galvanometer (MEMS mirror) belongs to an optical MEMS actuator chip and can deflect, modulate, open and close a laser beam and control the phase under the driving action. The method is widely applied to scenes such as projection, display, optical communication and the like.

At present, with the technology and process of multiple links such as design, manufacture, sealing and testing becoming mature gradually, the development of the internet of things industry will be greatly promoted by using the MEMS as a product of physical sensing and execution of connecting semiconductor integrated circuits, and the MEMS will be more widely applied in the fields of consumer electronics, automotive electronics, industrial control, military industry, smart home, smart city and the like.

Disclosure of Invention

Some embodiments of the present disclosure provide a MEMS galvanometer and a method for fabricating the same, so that a rotating shaft of the MEMS galvanometer has excellent fatigue resistance.

In one aspect, a MEMS galvanometer is provided, the MEMS galvanometer comprising: the mirror vibration part, the outer frame, the rotating shaft part connected between the mirror vibration part and the outer frame, and the hydrophobic membrane. Wherein, the hydrophobic membrane covers the surface of the rotating shaft part at least.

In at least one embodiment of the present disclosure, the hydrophobic film comprises a Parylene film.

In at least one embodiment of the present disclosure, the hydrophobic film has a thickness of 10nm to 1000 nm.

In at least one embodiment of the present disclosure, the galvanometer section includes: the vibrating mirror comprises a vibrating mirror body and an isolation structure arranged in the circumferential direction of the vibrating mirror body.

In at least one embodiment of the present disclosure, the rotation shaft portion includes: the fast shaft is arranged between the mirror vibrating part and the outer frame and is connected with the mirror vibrating part; a slow shaft arranged between the mirror vibrating part and the outer frame and connected with the outer frame; and a movable frame connected between the fast axis and the slow axis.

In at least one embodiment of the present disclosure, the MEMS galvanometer further comprises: and the reflecting layer is at least arranged on the surface of the vibrating mirror part.

In another aspect, a method for fabricating a MEMS galvanometer is provided, the method comprising:

providing a base layer;

a galvanometer part of the MEMS galvanometer, an outer frame and a rotating shaft part connected between the galvanometer part and the outer frame are formed in the substrate layer; and the number of the first and second groups,

a hydrophobic film is formed on at least the outer surface of the rotating shaft.

In at least one embodiment of the present disclosure, the base layer comprises a silicon substrate or a SOI silicon wafer.

In at least one embodiment of the present disclosure, the base layer includes an SOI silicon wafer including an insulating substrate and a first fabrication layer and a second fabrication layer respectively located on opposite sides of the insulating substrate; form mirror portion, the frame that shakes of MEMS galvanometer and connect the pivot portion between mirror portion and the frame in the stratum basale, include:

forming a mirror portion in the first production layer; the galvanometer part comprises a galvanometer body and an isolation structure, wherein the isolation structure is arranged in the circumferential direction of the galvanometer body;

etching the second manufacturing layer to form a back cavity;

forming a rotating shaft part in the first manufacturing layer;

and removing the insulating substrates between the rotating shaft part and the back cavity and between the vibrating mirror part and the back cavity, so that the vibrating mirror part and the rotating shaft part form a suspended structure.

In at least one embodiment of the present disclosure, forming a mirror portion in a first fabrication layer includes:

coating photoresist on one side of the first manufacturing layer, which is back to the insulating substrate;

etching the photoresist by using the channel layer mask plate, and taking the patterned photoresist as a mask for etching the channel structure in the first manufacturing layer;

etching the first manufacturing layer to the junction with the insulating substrate to form a vibrating mirror body and a channel structure surrounding the circumference of the vibrating mirror body;

removing the photoresist;

and filling silicon nitride into the channel structure to form an isolation structure.

In at least one embodiment of the present disclosure, before filling the silicon nitride into the channel structure, forming a mirror portion at the first fabrication layer further includes: and forming an oxide insulating layer on the side wall of the channel structure.

In at least one embodiment of the present disclosure, forming a mirror portion in a first production layer further includes: and carrying out chemical mechanical polishing on the surfaces of the first manufacturing layer and the second manufacturing layer, and removing the oxide insulating layer and the silicon nitride on the surfaces of the first manufacturing layer and the second manufacturing layer.

In at least one embodiment of the present disclosure, etching the second fabrication layer to form a back cavity includes:

forming a sacrificial layer on one side of the second manufacturing layer, which is back to the insulating substrate;

etching the sacrificial layer, and taking the patterned sacrificial layer as a mask for etching the second manufacturing layer;

etching the second manufacturing layer to the junction with the insulating substrate to form a back cavity;

and removing the sacrificial layer.

In at least one embodiment of the present disclosure, before forming the isolation structure in the first fabrication layer, the MEMS galvanometer fabrication method further includes: and removing the native oxide layer on the surface of the SOI silicon wafer by using a hydrofluoric acid solution, cleaning the SOI silicon wafer by using deionized water, and then drying.

In at least one embodiment of the present disclosure, before forming the hydrophobic film on at least the outer surface of the spindle portion, the MEMS galvanometer manufacturing method further includes: and forming a reflecting layer on one side of the first manufacturing layer, which is back to the insulating substrate, wherein the reflecting layer is at least arranged on the surface of the vibrating mirror part.

In at least one embodiment of the present disclosure, the method for manufacturing the MEMS galvanometer further includes: and splitting the substrate layer to obtain a plurality of MEMS galvanometers.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the disclosure and together with the description serve to explain the principles of the disclosure.

FIG. 1 is a schematic diagram of a MEMS galvanometer structure according to some embodiments;

FIG. 2 is a schematic diagram of another MEMS galvanometer structure according to some embodiments;

FIG. 3 is a cross-sectional view taken along line A-B of FIG. 2;

FIG. 4 is a cross-sectional view taken along line C-C of FIG. 2;

FIG. 5 is a cross-sectional view taken along line D-D of FIG. 2;

FIG. 6 is a flow chart of a method of fabricating a MEMS galvanometer according to some embodiments;

FIG. 7 is a flow chart of another method of fabricating a MEMS galvanometer according to some embodiments;

fig. 8 is a flowchart of a method for manufacturing a MEMS galvanometer, in which a galvanometer portion of the MEMS galvanometer, a frame, and a rotating shaft portion connected between the galvanometer portion and the frame are formed in a base layer according to some embodiments;

FIG. 9 is a flow chart of a method of fabricating a MEMS galvanometer in a first fabrication layer to form a galvanometer portion in the first fabrication layer according to some embodiments;

FIG. 10 is a flow chart of forming a back cavity in a method of fabricating a MEMS galvanometer according to some embodiments;

FIG. 11 is a flow chart of yet another method of fabricating a MEMS galvanometer according to some embodiments.

Reference numerals:

10-MEMS galvanometer, 100-galvanometer part, 110-galvanometer body, 120-isolation structure, 200-outer frame, 300-rotating shaft part, 310-fast shaft, 320-slow shaft, 330-movable frame, 400-hydrophobic film, 500-reflecting layer, 600-base layer, 610-insulating substrate, 620-first manufacturing layer, 621-channel structure, 630-second manufacturing layer, 631-back cavity, 700-oxide insulating layer and 800-silicon nitride.

Detailed Description

The present disclosure will be described in further detail with reference to the drawings and embodiments. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not to be construed as limitations of the present disclosure. It should be further noted that, for the convenience of description, only the portions relevant to the present disclosure are shown in the drawings.

It should be noted that the embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict. The present disclosure will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

It should be noted that, the step numbers in the text are only for convenience of explanation of the specific embodiments, and do not serve to limit the execution sequence of the steps.

As mentioned in the background, MEMS has a wide range of applications, but the fragile nature of MEMS devices makes them potentially catastrophic in a vibrating environment. In particular, in a vibration environment, the rotating shaft of the MEMS galvanometer may be bent excessively to cause surface adhesion or fracture, and long-term galvanometer vibration causes the reciprocating motion of the structure, which may also cause fatigue failure. The spindle material of the existing MEMS galvanometer is generally monocrystalline silicon or polycrystalline silicon, on one hand, the material itself may have initial microcracks or surface defects, and on the other hand, a natural oxide layer silicon dioxide layer formed on the silicon surface is easy to generate stress corrosion cracking, so that the spindle is easy to generate fatigue fracture.

Based on the above, some embodiments of the present disclosure provide a MEMS galvanometer and a method for manufacturing the MEMS galvanometer, so that a rotating shaft of the MEMS galvanometer has excellent fatigue resistance.

As shown in fig. 1-5, some embodiments of the present disclosure provide a MEMS galvanometer 10, the MEMS galvanometer 10 including: a vibrating mirror part 100, a frame 200, a rotating shaft part 300 connected between the vibrating mirror part 100 and the frame 200, and a hydrophobic membrane 400. The hydrophobic film 400 covers at least the outer surface of the rotation shaft 300.

The galvanometer part 100 may be square, circular, oval or other shapes. The rotating shaft 300 may be a strip shaft, a toothed shaft or other regular or irregular shape; the shaft portion 300 may be in the form of a single shaft, a double shaft, or a multiple shaft.

The hydrophobic film 400 covers at least the outer surface of the rotation shaft 300, that is, the hydrophobic film 400 may cover the outer surface of the rotation shaft 300, or the hydrophobic film 400 may cover the outer surface of the rotation shaft 300 and the outer surface of the mirror oscillating unit 100, or the hydrophobic film 400 may cover the outer surface of the rotation shaft 300, the outer surface of the mirror oscillating unit 100, and the outer surface of the outer frame 200. From the perspective of the manufacturing process, the formed hydrophobic film 400 has good coating property, so that all exposed surfaces of the rotating shaft 300, the mirror-vibrating portion 100 and even the outer frame 200 can be wrapped, and since the hydrophobic film 400 is extremely thin, the covering of the hydrophobic film 400 on the mirror-vibrating portion 100 or the outer frame 200 has no influence on the performance of the whole MEMS mirror-vibrating 10, so that the hydrophobic film 400 at the mirror-vibrating portion 100 or the outer frame 200 does not need to be removed, thereby simplifying the process steps and saving the manufacturing time and the manufacturing cost. Thus, a MEMS mirror oscillator product in which the outer surface of the rotation shaft 300, the outer surface of the mirror oscillator 100, and the outer surface of the outer frame 200 are covered with the hydrophobic film 400 is obtained. Of course, the hydrophobic film 400 at the galvanometer part 100 and/or the outer frame 200 may be removed by a corresponding process, and the hydrophobic film 400 of the rotation shaft 300 may be retained.

The MEMS galvanometer 10 provided by some embodiments of the present disclosure may solve the problem that the rotating shaft 300 of the MEMS galvanometer 10 is prone to fatigue fracture under high frequency vibration by forming a hydrophobic thin layer, i.e., the hydrophobic film 400, on at least the surface of the rotating shaft 300. The hydrophobic membrane 400 has the functions of hydrophobic property and isolating ambient air, can prevent the surface of the rotating shaft part 300 from generating a silicon dioxide layer, and avoids the stress corrosion cracking effect of silicon dioxide, thereby improving the fatigue resistance of the rotating shaft part 300, further improving the structural stability of the MEMS vibrating mirror 10 and prolonging the service life of the MEMS vibrating mirror 10.

In some embodiments, hydrophobic membrane 400 comprises a Parylene film.

Parylene is a generic term for polymers having a Parylene structure prepared by chemical vapor deposition, mainly used as films and coatings, commonly used for electrical insulation media for electronic components, protective coatings, packaging materials, and the like. In some embodiments of the present disclosure, the Parylene film is creatively used as the outer coating film of the rotating shaft portion 300, characteristics of good sealing performance, good durability and the like of the Parylene material are fully utilized, the surface of the rotating shaft portion 300 can be prevented from generating a silicon dioxide layer through hydrophobic property of the Parylene film and air isolation in the environment, a stress corrosion cracking effect of silicon dioxide is avoided, and thus the rotating shaft portion 300 of the MEMS mirror 10 can still maintain excellent fatigue resistance under a high-frequency vibration condition. In addition, the use of Parylene film can make the spindle 300 have good electrical properties, heat resistance and chemical stability. Therefore, the hydrophobic film 400 structure adopts a Parylene film, which can improve the structural stability of the MEMS galvanometer 10 and increase the service life of the MEMS galvanometer 10.

In some embodiments, the hydrophobic film 400 has a thickness of 10nm to 1000 nm. The Parylene film can be prepared by a vacuum pyrolysis vapor deposition process, can be made into an extremely thin film, and has no influence on the reflection function of the MEMS galvanometer 10 even if the Parylene film covers the galvanometer part 100 or the outer frame 200. Even a Parylene film covering the mirror portion 100 may increase the fatigue resistance of the mirror portion 100 to some extent.

If the Parylene film is too thick, for example, greater than 1000nm, the mass of the rotating shaft 300 and the vibrating mirror 100 will be increased, and the fatigue of the rotating shaft 300 will be increased to some extent, and the reflectivity of the vibrating mirror surface to the laser will be affected. Therefore, the thickness of the Parylene film is 10 nm-1000 nm, and a good anti-fatigue effect of the vibrating mirror can be achieved.

As shown in fig. 2 to 5, in some embodiments, the galvanometer part 100 includes: the vibrating mirror comprises a vibrating mirror body 110 and an isolation structure 120 arranged on the circumferential direction of the vibrating mirror body 110.

The isolation structure 120 is formed of silicon nitride. Alternatively, the isolation structure 120 is a sandwich structure of silicon oxide layers and silicon nitride layers. The isolation structure 120 is used to electrically isolate the galvanometer body 110 from the rotary shaft portion 300.

In some embodiments, the spindle portion 300 includes: a fast axis 310 disposed between the mirror oscillator 100 and the frame 200 and connected to the mirror oscillator 100; a slow shaft 320 disposed between the mirror oscillator 100 and the frame 200 and connected to the frame 200; and a movable frame 330 connected between the fast axis 310 and the slow axis 320. Wherein, the fast axis 310 has a fast vibration frequency, the slow axis 320 is slender and has a large torsion angle.

In at least one embodiment of the present disclosure, the MEMS galvanometer 10 further comprises: a reflective layer 500 disposed on at least the surface of the mirror unit 100. The reflective layer 500 may be a metal reflective layer 500 for reflecting laser light.

For the MEMS galvanometer 10 that reflects red laser light, the reflective layer 500 may be a gold layer or a gold-titanium alloy layer to increase the reflectivity for red light.

The reflective layer 500 is at least disposed on the surface of the mirror unit 100, that is, the reflective layer 500 may be disposed on the surface of the mirror unit 100, or the reflective layer 500 may be disposed on the surfaces of the rotating shaft 300 and the mirror unit 100, or the reflective layer 500 may be disposed on the surface of the rotating shaft 300, the surface of the mirror unit 100, and the surface of the outer frame 200. From the perspective of the manufacturing process, the reflection layer 500 covering the vibrating mirror portion 100 or the outer frame 200 does not affect the performance of the whole MEMS vibrating mirror, and even the reflection layer 500 disposed on the surface of the rotating shaft portion 300 can increase the fatigue resistance of the rotating shaft portion 300 to a certain extent, so that the reflection layer 500 at the rotating shaft portion 300 or the outer frame 200 does not need to be removed, thereby simplifying the process steps and saving the manufacturing time and the manufacturing cost. Thus, a MEMS mirror product in which the reflective layer 500 is provided on the surface of the rotation shaft 300, the surface of the mirror portion 100, and the surface of the outer frame 200 is obtained. Of course, the reflective layer 500 on the spindle portion 300 and/or the outer frame 200 is removed by a corresponding process, and the reflective layer 500 on the surface of the mirror portion 100 may be remained.

Some embodiments of the present disclosure further provide a method for manufacturing a MEMS galvanometer, as shown in fig. 6, the method includes steps S100 to S300.

S100, providing a base layer 600.

The base layer 600 is, for example, a silicon substrate or an SOI silicon wafer. Among them, SOI is called Silicon-On-Insulator, i.e., Silicon On an insulating substrate.

It is understood that a plurality of MEMS mirrors 10 can be formed on one substrate layer 600 through one manufacturing process.

S200, the galvanometer portion 100 of the MEMS galvanometer 10, the frame 200, and the rotation shaft portion 300 connected between the galvanometer portion 100 and the frame 200 are formed in the base layer 600.

And S300, forming a hydrophobic film 400 on at least the outer surface of the rotating shaft part 300.

Because the formed hydrophobic membrane 400 has good coating property, all exposed surfaces of the rotating shaft part 300, the mirror vibrating part 100 and even the outer frame 200 can be wrapped, and because the hydrophobic membrane 400 is extremely thin, the performance of the whole MEMS mirror vibrator 10 is not affected by covering the mirror vibrating part 100 or the outer frame 200 with a layer of hydrophobic membrane 400, the hydrophobic membrane 400 at the mirror vibrating part 100 or the outer frame 200 does not need to be removed, so that the process steps are simplified, and the manufacturing time and the manufacturing cost are saved. Thus, a MEMS mirror oscillator product in which the outer surface of the rotation shaft 300, the outer surface of the mirror oscillator 100, and the outer surface of the outer frame 200 are covered with the hydrophobic film 400 is obtained.

Of course, the hydrophobic film 400 at the galvanometer part 100 and/or the outer frame 200 may be removed by a corresponding process, and the hydrophobic film 400 of the rotation shaft 300 may be retained. For example, the rotation shaft may be covered with a photoresist, the hydrophobic film 400 at the position of the galvanometer part 100 and/or the outer frame 200 may be etched by a plasma etching method, and finally the photoresist on the surface of the rotation shaft 300 may be etched by an acetone solution, so as to obtain the MEMS galvanometer 10 in which the rotation shaft 300 is covered with the hydrophobic film 400.

In some embodiments, hydrophobic membrane 400 comprises a Parylene film. Illustratively, a layer of Parylene film with a thickness of 10nm to 1000nm is formed on the outer surface of the rotating shaft 300, the outer surface of the galvanometer part 100 and the outer surface of the outer frame 200 by a Low Pressure Chemical Vapor Deposition (LPCVD) method to increase the fatigue resistance of the rotating shaft 300.

According to the method for manufacturing the MEMS galvanometer provided by some embodiments of the present disclosure, the problem that the rotating shaft 300 of the MEMS galvanometer 10 is easily fatigue-broken under high-frequency vibration can be solved by forming a hydrophobic thin layer, that is, the hydrophobic film 400, on at least the surface of the rotating shaft 300. The hydrophobic membrane 400 has the functions of hydrophobic property and isolating ambient air, can prevent the surface of the rotating shaft part 300 from generating a silicon dioxide layer, and avoids the stress corrosion cracking effect of silicon dioxide, thereby improving the fatigue resistance of the rotating shaft part 300, further improving the structural stability of the MEMS vibrating mirror 10 and prolonging the service life of the MEMS vibrating mirror 10.

The following describes a method for fabricating a MEMS galvanometer according to some embodiments of the present disclosure, taking an SOI wafer as an example of the substrate layer 600. It will be appreciated that in embodiments where a silicon substrate is used as the base layer 600, the same effect of etching silicon layers on both sides of an SOI silicon wafer to the insulating substrate 610 can be achieved by controlling the depth of etching on both sides of the silicon substrate.

In some embodiments, the base layer 600 comprises a SOI silicon wafer comprising an insulating substrate 610 and first and second fabrication layers 620, 630 respectively located on opposite sides of the insulating substrate 610. The insulating substrate 610 is a silicon oxide layer, and the first fabrication layer 620 and the second fabrication layer 630 are silicon layers. As shown in FIGS. 8 and 11, step S200 includes S210-S240.

S210, the mirror portion 100 is formed in the first formation layer 620. The galvanometer part 100 includes a galvanometer body 110 and an isolation structure 120, wherein the isolation structure 120 is disposed in a circumferential direction of the galvanometer body 110.

It should be noted that before the mirror portion 100 is formed in the first manufacturing layer 620, the SOI wafer may be pretreated. In some embodiments, before step S210, the method for fabricating the MEMS galvanometer further includes: and removing the native oxide layer on the surface of the SOI silicon wafer by using a hydrofluoric acid solution, cleaning the SOI silicon wafer by using deionized water, and then drying. The pretreatment of the SOI silicon wafer is beneficial to the subsequent process, and the formed MEMS galvanometer 10 device has better performance.

As shown in FIGS. 9 and 11, in some embodiments, in step S210, the mirror portion 100 is formed in the first fabrication layer 620, including S211-S215.

S211, coating a photoresist on a side of the first fabrication layer 620 opposite to the insulating substrate 610.

S212, the channel layer mask is used to etch the photoresist, and the patterned photoresist is used as a mask for etching the channel structure 621 in the first manufacturing layer 620.

S213, the first manufacturing layer 620 is etched to the boundary with the insulating substrate 610, so as to form the galvanometer body 110 and a trench structure 621 surrounding the galvanometer body 110.

For example, the first fabrication layer 620 may be dry etched in an Inductively Coupled Plasma (ICP) etching system using the patterned photoresist as a mask until the first fabrication layer is etched to the interface with the insulating substrate 610, so as to form the resonator mirror body 110 and a channel structure 621 surrounding the resonator mirror body 110.

And S214, removing the photoresist.

For example, the photoresist may be removed by an oxygen plasma cleaning or ultrasonic cleaning with an acetone deglued solution.

S215, filling the channel structure 621 with silicon nitride 800 to form the isolation structure 120.

For example, a silicon nitride medium may be backfilled in the ICP etched channel structure 621 by a Low Pressure Chemical Vapor Deposition (LPCVD) method to form the final isolation structure 120. The filled silicon nitride 800 can achieve electrical isolation between the galvanometer body 110 and the spindle portion 300.

In some embodiments, before step S215, step S210 further comprises: s216, an oxide insulating layer 700 is formed on the sidewall of the trench structure 621.

For example, an oxide insulating layer 700 may be formed on the sidewalls of the channel structure 621 etched by ICP etching by wet oxidation to a thickness of about 100 nm. Since the silicon nitride film 800 on the side of the first fabrication layer 620 facing away from the insulating substrate 610 needs to be removed in the subsequent steps, wet etching is long in time, multiple in steps, and difficult to control in precision. And after depositing silicon oxide on the sidewall of the channel structure 621, filling silicon nitride 800, the silicon nitride film 800 on the side of the first fabrication layer 620 facing away from the insulating substrate 610 can be removed relatively easily in the subsequent steps, thereby saving the operation time and steps.

In some embodiments, after step S215, step S210 further comprises: s217, performing chemical mechanical polishing on the surfaces of the first fabrication layer 620 and the second fabrication layer 630, and removing the oxide insulating layer 700 and the silicon nitride layer 800 on the surfaces of the first fabrication layer 620 and the second fabrication layer 630.

S220, the second fabrication layer 630 is etched to form a back cavity 631.

The back cavity 631 serves to provide space for the vibration of the spindle portion and the galvanometer portion. The back cavity 631 may be a cavity of any shape as long as it does not affect the vibration of the rotation shaft portion and the galvanometer portion.

As shown in FIG. 10, in some embodiments, step S220 includes S221-S224.

S221, a sacrificial layer is formed on a side of the second fabrication layer 630 facing away from the insulating substrate 610.

S222, etching the sacrificial layer, and taking the patterned sacrificial layer as a mask for etching the second manufacturing layer 630;

s223, etching the second manufacturing layer 630 to the interface with the insulating substrate 610 to form a back cavity 631;

and S224, removing the sacrificial layer.

Here, the material forming the sacrificial layer may be photoresist, metal, or the like. Taking aluminum as an example of the sacrificial layer material, the step of forming the back cavity 631 may be: sputtering and depositing an aluminum film on the side, opposite to the insulating substrate 610, of the second manufacturing layer 630 by using a magnetron sputtering device; in the aluminum etching liquid with a certain concentration ratio, the aluminum film is etched by a wet method, and a mask pattern of the back cavity 631 is formed in the aluminum film; in an ICP etching system, dry etching is adopted to etch the second manufacturing layer 630 to the interface with the insulating substrate 610, so as to form a back cavity 631; finally, the aluminum mask is removed.

S230, the spindle 300 is formed in the first formation layer 620.

Illustratively, coating photoresist on one side of the first manufacturing layer 620, which faces away from the insulating substrate 610, and performing photolithography by using a spindle 300 mask, wherein the patterned photoresist is to be used as a mask for ICP etching of the spindle 300; the first fabrication layer 620 is dry etched in an ICP etching system until the interface with the insulating substrate 610 is etched, forming the spindle 300.

S240, the insulating substrate 610 between the rotation shaft 300 and the back cavity 631 and between the galvanometer unit 100 and the back cavity 631 is removed, so that the galvanometer unit 100 and the rotation shaft 300 are suspended.

For example, a hydrofluoric acid solution may be used to etch away silicon oxide under the galvanometer part 100 and the spindle part 300.

It is understood that the MEMS resonator 10 provided by some embodiments of the present disclosure can be formed if the order of the step of forming the back cavity 631 in S220 and the step of forming the spindle 300 in S230 is reversed.

As shown in fig. 7, in some embodiments, before step S300, the method for fabricating a MEMS galvanometer further includes: s400, forming a reflective layer 500 on a side of the first manufacturing layer 620 opposite to the insulating substrate 610, wherein the reflective layer 500 is at least disposed on the surface of the mirror portion 100.

The reflective layer 500 is at least disposed on the surface of the mirror unit 100, that is, the reflective layer 500 may be disposed on the surface of the mirror unit 100, or the reflective layer 500 may be disposed on the surfaces of the rotating shaft 300 and the mirror unit 100, or the reflective layer 500 may be disposed on the surface of the rotating shaft 300, the surface of the mirror unit 100, and the surface of the outer frame 200. In the reflective layer 500, the reflective layer 500 is formed so as to cover the surface of the rotating shaft 300, the surface of the galvanometer unit 100, and the surface of the outer frame 200. The reflection layer 500 covering the mirror-vibrating portion 100 or the outer frame 200 does not affect the performance of the whole MEMS mirror-vibrating 10, and even the reflection layer 500 disposed on the surface of the rotating shaft portion 300 can increase the fatigue resistance of the rotating shaft portion 300 to a certain extent, so that the reflection layer 500 at the position of the rotating shaft portion 300 or the outer frame 200 does not need to be removed, thereby simplifying the process steps and saving the manufacturing time and the manufacturing cost. Of course, the reflective layer 500 at the spindle portion 300 and/or the outer frame 200 is removed by a corresponding process, and it is also possible to retain the reflective layer 500 of the mirror portion 100.

Illustratively, a gold film is evaporated on the side of the first fabrication layer 620 opposite to the insulating substrate 610 by electron beam evaporation to increase the reflectivity to red light emitted from a red laser.

As shown in fig. 7, in some embodiments, the method for manufacturing the MEMS galvanometer 10 further includes: s500, the base layer 600 is split to obtain a plurality of MEMS mirrors 10.

The following describes in detail a method for fabricating a MEMS galvanometer according to some embodiments of the present disclosure with reference to fig. 11 by taking the MEMS galvanometer 10 shown in fig. 2 as an example. Note that fig. 11 shows a variation in the a-B section in fig. 2 during the manufacturing process.

As shown in fig. 11, the method for manufacturing the MEMS galvanometer 10 includes the following steps.

An SOI silicon wafer in which a plurality of MEMS mirrors 10 are to be formed is provided as the base layer 600.

And removing the native oxide layer on the surface of the SOI silicon wafer by using a hydrofluoric acid solution, cleaning the SOI silicon wafer by using deionized water, and then drying.

A photoresist is applied to the side of the first fabrication layer 620 facing away from the insulating substrate 610.

The photoresist is etched using the channel layer mask, and the patterned photoresist is used as a mask for etching the channel structure 621 in the first fabrication layer 620.

In an Inductively Coupled Plasma (ICP) etching system, the first fabrication layer 620 is dry etched using the patterned photoresist as a mask until reaching the interface with the insulating substrate 610, so as to form the galvanometer body 110 and a channel structure 621 surrounding the galvanometer body 110 in the circumferential direction.

And removing the photoresist by using an oxygen plasma cleaning method.

An oxide insulating layer 700 is formed on the sidewall of the channel structure 621 etched by ICP by wet oxidation, and the thickness is about 100 nm.

The channel structure 621 etched by ICP is backfilled with silicon nitride 800 medium by Low Pressure Chemical Vapor Deposition (LPCVD), more specifically, in the oxide insulating layer 700 formed on the sidewall of the channel structure 621, to form the isolation structure 120.

The surfaces of the first fabrication layer 620 and the second fabrication layer 630 are chemically and mechanically polished to remove the oxide insulating layer 700 and the silicon nitride 800 layer on the surfaces of the first fabrication layer 620 and the second fabrication layer 630.

A magnetron sputtering device is used to sputter deposit a layer of aluminum film on the side of the second fabrication layer 630 facing away from the insulating substrate 610.

Wet etching the aluminum film in certain concentration ratio to form back cavity 631 mask pattern

In the ICP etching system, dry etching is used to etch the second fabrication layer 630 to the interface with the insulating substrate 610, forming a back cavity 631.

And removing the aluminum film.

And coating photoresist on the side of the first manufacturing layer 620, which faces away from the insulating substrate 610, and performing photoetching by using a rotating shaft mask.

The patterned photoresist is used as a mask for ICP etching of the spindle 300, and the first fabrication layer 620 is dry etched in an ICP etching system until the interface with the insulating substrate 610 is etched, thereby forming the spindle 300.

The silicon oxide under the galvanometer part 100 and the rotating shaft part 300 is etched by hydrofluoric acid solution, so that the galvanometer part 100 and the rotating shaft part 300 are suspended.

And evaporating a gold film on the side of the first manufacturing layer 620, which faces away from the insulating substrate 610, by using an electron beam evaporation method so as to increase the reflectivity of the galvanometer body 110 to red light.

A 100nm Parylene film is coated on the side of the reflective layer 500 opposite to the insulating substrate 610 by a Low Pressure Chemical Vapor Deposition (LPCVD) method to increase the fatigue resistance of the spindle portion 300.

And splitting the SOI silicon wafer to obtain a plurality of MEMS galvanometers 10.

In the description herein, reference to the description of the terms "one embodiment/mode," "some embodiments/modes," "example," "specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment/mode or example is included in at least one embodiment/mode or example of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to be the same embodiment/mode or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments/modes or examples. Furthermore, the various embodiments/aspects or examples and features of the various embodiments/aspects or examples described in this specification can be combined and combined by one skilled in the art without conflicting therewith.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present disclosure, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specifically limited otherwise. "and/or" is simply an association that describes an associated object, meaning three relationships, e.g., A and/or B, expressed as: a exists alone, A and B exist simultaneously, and B exists alone. The terms "upper," "lower," "left," "right," "inner," "outer," and the like, indicate orientations or positional relationships that are based on the orientations or positional relationships shown in the drawings, are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be taken as limiting the present disclosure. Meanwhile, in the description of the present disclosure, unless otherwise explicitly specified or limited, the terms "connected" and "connected" should be interpreted broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; the connection can be mechanical connection or electrical connection; may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the present disclosure can be understood by those of ordinary skill in the art as appropriate.

It will be understood by those skilled in the art that the foregoing embodiments are merely for clarity of illustration of the disclosure and are not intended to limit the scope of the disclosure. Other variations or modifications may occur to those skilled in the art, based on the foregoing disclosure, and are still within the scope of the present disclosure.

Claims

1. A MEMS galvanometer, comprising:

a mirror vibrating section;

an outer frame;

a rotating shaft part connected between the mirror vibrating part and the outer frame; and the number of the first and second groups,

a hydrophobic membrane; wherein, the hydrophobic membrane coats the surface of the rotating shaft part at least.

2. The MEMS galvanometer of claim 1 wherein the hydrophobic membrane comprises a Parylene film.

3. The MEMS galvanometer of claim 1, wherein the galvanometer section comprises: the vibrating mirror comprises a vibrating mirror body and an isolation structure arranged in the circumferential direction of the vibrating mirror body.

4. The MEMS galvanometer of claim 1, wherein the spindle portion comprises:

the fast shaft is arranged between the mirror vibrating part and the outer frame and is connected with the mirror vibrating part;

the slow shaft is arranged between the mirror vibrating part and the outer frame and connected with the outer frame; and the number of the first and second groups,

a movable frame connected between the fast axis and the slow axis.

5. A method for manufacturing a MEMS galvanometer is characterized by comprising the following steps:

providing a base layer;

forming a galvanometer part of an MEMS galvanometer, an outer frame and a rotating shaft part connected between the galvanometer part and the outer frame in the base layer; and the number of the first and second groups,

a hydrophobic film is formed on at least an outer surface of the shaft portion.

6. The method of claim 5, wherein the hydrophobic film comprises a Parylene film.

7. The method for manufacturing the MEMS galvanometer according to claim 5, wherein the base layer comprises an SOI silicon wafer comprising an insulating substrate and a first manufacturing layer and a second manufacturing layer respectively positioned at two opposite sides of the insulating substrate;

the mirror portion that shakes that forms MEMS galvanometer in the stratum basale, frame and connect in shake mirror portion with pivot portion between the frame includes:

etching the second manufacturing layer to form a back cavity;

forming a rotating shaft part in the first manufacturing layer;

and removing the insulating substrates between the rotating shaft part and the back cavity and between the mirror vibration part and the back cavity, so that the mirror vibration part and the rotating shaft part form a suspended structure.

8. The method of claim 7, wherein the forming a mirror portion in the first fabrication layer comprises:

coating photoresist on one side of the first manufacturing layer, which faces away from the insulating substrate;

etching the photoresist by using a channel layer mask plate, and taking the patterned photoresist as a mask for etching the channel structure in the first manufacturing layer;

removing the photoresist;

forming an oxide insulating layer on the side wall of the channel structure;

9. The MEMS galvanometer manufacturing method according to claim 7, wherein before the forming of the hydrophobic film on at least an outer surface of the spindle portion, the MEMS galvanometer manufacturing method further comprises: and forming a reflecting layer on one side of the first manufacturing layer, which faces away from the insulating substrate, wherein the reflecting layer is at least arranged on the surface of the vibrating mirror part.

10. The method for manufacturing the MEMS galvanometer of claim 5, further comprising: and splitting the substrate layer to obtain a plurality of MEMS galvanometers.