System and method of fabricating micro cavities

• US 7,265,429 B2
• Filed: 06/01/2004
• Issued: 09/04/2007
• Est. Priority Date: 08/07/2002
• Status: Expired due to Fees

• Current Assignee: Chang-Feng Wan
• Original Assignee: Chang-Feng Wan
• Inventors: Wan, Chang-Feng
• Primary Examiner(s): TRINH, MICHAEL MANH
• Application Number:
  US10/858,017
• Publication Number:
  US 20040219706A1
• Time in Patent Office: 1,190 Days
• Field of Search: 257/415, 257/414, 257/416, 257/419, 257/420, 257/417
• US Class Current: 257/415
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 2203/0307 Anchors
• CPC Class Codes: B81B 2203/0384 sloped profile
• CPC Class Codes: B81B 2207/07 Interconnects
• CPC Class Codes: B81C 1/00095 Interconnects
• CPC Class Codes: B81C 1/00285 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81C 1/00333 Aspects relating to packaging of MEMS devices, not covered by groups B81C1/00269 - B81C1/00325
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: H01L 29/82 controllable by variation of the magnetic field applied to the device

Abstract

A system and method for manufacturing micro cavities at the wafer level using a unique, innovative MEMS (MicroElectroMechanical Systems) process, wherein micro cavities are formed, with epoxy bonded single-crystalline silicon membrane as cap and deposited and/or electroplated metal as sidewall, on substrate wafers. The epoxy is also the sacrificial layer. It is totally removed from within the cavity through small etch access holes etched in the silicon cap before the etch access holes are sealed under vacuum. The micro cavities manufactured therein can be used as pressure sensors or for packaging MEMS devices under vacuum or inert environment. In addition, the silicon membrane manufactured therein can be used to manufacture RF switches.

Claims

1. A stepping electrostatic actuator of a MEMS device, comprising:

a substrate;

a suspended medial plate;

a plurality of suspended side electrodes and fixed side electrodes, wherein all of said suspended medial plate and said plurality of suspended side electrodes are substantially at the same height and are linked with springs, said fixed side electrodes and said suspended side electrodes form at least one set of side parallel-plate electrostatic actuators, wherein said side parallel-plate electrostatic actuators of each said set of side parallel-plate electrostatic actuators have incremental gaps between said suspended side electrodes and said fixed side electrodes;

said fixed side electrodes form a plurality of stairs.

2. The stepping electrostatic actuator of claim 1, wherein said side parallel-plate electrostatic actuators are distributed symmetrically on the two opposite sides of said medial plate.

3. The stepping electrostatic actuator of claim 1, each of said stairs comprises at least one said side fixed electrodes, and said fixed electrodes are electrically insulated from each other and are electrically biased individually or collectively.

4. The stepping electrostatic actuator of claim 1, wherein said suspended medial plate further comprises a first mirror and said substrate comprises a second mirror, wherein said first mirror and said second mirror are parallel to each other to form a tunable Fabry-Perot filter.

5. The stepping electrostatic actuator of claim 1, wherein said suspended medial plate further comprises a suspended main electrode, said substrate further comprises a fixed signal electrode, said suspend main electrode and said fixed signal electrode form a variable capacitor.

6. The stepping electrostatic actuator of claim 1, wherein said suspended medial plate further comprises a suspended main electrode, said substrate further comprises a fixed signal electrode, said suspend main electrode and said fixed signal electrode form a contact switch.

7. A stepping electrostatic actuator of a MEMS device, comprising a suspended medial plate, at least one set of suspended side electrodes, and at least one set of fixed side electrodes, forming at least one set of side parallel-plate electrostatic actuators, wherein all of said suspended medial plate and said suspended side electrodes are connected side-by-side with spring fixtures and are substantially at the same height, one end of each said set of suspended side electrodes is anchored to a substrate, the other end of each said set of suspended side electrodes is connected to said suspended medial plate, the gaps between said suspended electrodes and said fixed electrodes of said side parallel-plate electrostatic actuators have incremental increases from the anchored end to the medial-plate end, and said at least one set of fixed electrodes form a plurality of stairs.

8. The stepping electrostatic actuator in claim 7 comprises two said sets of side parallel-plate electro-static actuators, distributed symmetrically on the two opposite sides of said medial plate, wherein each said set of fixed side electrodes form a set of stairs wherein each step of said stairs comprises at least one said fixed electrodes.