MEMS Automatic Alignment High-And-Low Comb Tooth and Manufacturing Method Thereof

• US 20170233244A1
• Filed: 05/11/2015
• Published: 08/17/2017
• Est. Priority Date: 10/30/2014
• Status: Active Grant

• Current Assignee: Wuxi Wio Technology Co., Ltd.
• Original Assignee: Wuxi Wio Technology Co., Ltd.
• Inventors: Chen, Qiao, Xie, Huikai
• Granted Patent: US 10,077,184 B2
• Time in Patent Office: Days
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2201/033 Comb drives
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 2203/0136 Comb structures
• CPC Class Codes: B81B 3/0037 For increasing stroke, i.e. achieve large displacement of actuated parts
• CPC Class Codes: B81C 1/00007 Assembling automatically hinged components, i.e. self-assembly processes self-assembly mechanisms B81B7/0003
• CPC Class Codes: B81C 1/0015 Cantilevers switches using MEMS H01H1/0036; electrostatic relays using micromechanics H01H59/0009; microelectro-mechanical resonators H03H9/02244
• CPC Class Codes: B81C 2201/013 Etching
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0822 for defining out-of-plane movement of the mass
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: H01G 5/16 using variation of distance between electrodes
• CPC Class Codes: H02N 1/008 Laterally driven motors, e.g. of the comb-drive type

Abstract

A MEMS self-aligned high-and-low comb tooth and manufacturing method thereof, the comb tooth having a lifting structure, the lifting structure generating a displacement in the vertical direction to drive the movement of a movable comb tooth or a fixed comb tooth attached thereto. The manufacturing method thereof adopts a silicon wafer, the lifting structure and the comb tooth are sequentially formed on a mechanical structure layer, the fixed comb tooth and the movable comb tooth are formed with the same etching process, and the stress in the lifting structure displaces the fixed comb tooth and the movable comb tooth in the vertical direction, thus forming the self-aligned high-and-low comb tooth.

Claims

1. MEMS self-aligning high/low comb teeth, comprising movable comb teeth, fixed comb teeth, and a lifting structure with one end fixed to a substrate and the other end connected to the movable comb teeth or the fixed comb teeth, wherein, the lifting structure comprises at least one bent beam section and at least one straight beam section, the bent beam and the straight beam together form at least one bent folded beam structure, the bent beam makes the folded beam structure displace in the vertical direction, and thereby drives the movable comb teeth/fixed comb teeth connected to the lifting structure to displace out of the plane of the fixed comb teeth/movable comb teeth, forming high/low comb teeth.

2. The MEMS self-aligning high/low comb teeth according to claim 1, wherein, in the lifting structure, at least one bent beam is located in front of the bend, while at least one bent beam is located behind the bend.

3. The MEMS self-aligning high/low comb teeth according to claim 1, wherein, the lifting structure comprises a uniform and continuous first material layer and a non-continuous and sectional second material layer covering the first material layer, the straight beam comprises the first material layer solely, while the bent beam comprises the first material layer and the covering second material layer.

4. The MEMS self-aligning high/low comb teeth according to claim 3, wherein, the first material layer is monocrystalline silicon or polycrystalline silicon.

5. The MEMS self-aligning high/low comb teeth according to claim 3, wherein, the second material layer is a single-layer film or multi-layer film.

6. The MEMS self-aligning high/low comb teeth according to claim 5, wherein, the second material layer is one or more layers of metal films.

7. The MEMS self-aligning high/low comb teeth according to claim 5, wherein, the second material layer is one or more layers of non-metal films.

8. The MEMS self-aligning high/low comb teeth according to claim 5, wherein, the second material layer is a composite film comprising at least one layer of metal film and one layer of non-metal film.

9. A method of manufacturing a MEMS self-aligning high/low comb teeth, comprising the steps of:

employing a silicon wafer having a silicon-on-insulator (SOI) substrate including a front side and a back side;

depositing a film layer on a monocrystalline silicon component layer on the front side of the SOI substrate, and patterning the film layer to form a second material layer for lifting structure, the second material layer also being a film layer;

etching the back side of the SOI substrate by deep silicon etching, to form back cavities;

etching the monocrystalline silicon component layer on the front side of the SOI substrate to form fixed or movable comb teeth and a first material layer for the lifting structure;

bending locally a folded beam structure by virtue of the internal stress in the film layer, so that the lifting structure composed of the locally bent folded beam structure drives the fixed comb teeth or the movable comb teeth connected to the lifting structure to move in the vertical direction, and thereby forms self-aligning comb teeth.

10. The manufacturing method of the MEMS self-aligning high/low comb teeth according to claim 9, wherein, air pressure, temperature, and deposition rate of the film layer are controlled in the film layer growth process, so as to control the internal stress in the film layer.