Microminiature moving device

• US 20090146228A1
• Filed: 12/01/2008
• Published: 06/11/2009
• Est. Priority Date: 03/03/2004
• Status: Active Grant

• Current Assignee: Japan Aviation Electronics Industry Limited
• Original Assignee: Japan Aviation Electronics Industry Limited
• Inventors: Yoshida, Satoshi, Mori, Keiichi, Imaki, Osamu, Hamada, Yoshihiko, Kondou, Kenji, Kato, Yoshichika
• Granted Patent: US 7,973,373 B2
• Time in Patent Office: Days
• US Class Current: 257/415
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2203/033 Trenches
• CPC Class Codes: B81B 7/0029 Protection against environmental influences not provided for in groups B81B7/0012 - B81B7/0025
• CPC Class Codes: B81C 1/00825 Protect against mechanical threats, e.g. against shocks, or residues B81C1/00261 take precedence
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: Y10T 29/49 Method of mechanical manufacture
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A microminiature moving device has disposed on a single-crystal silicon substrate movable elements such as a movable rod and a movable comb electrode that are displaceable in parallel to the substrate surface and stationary parts that are fixedly secured to the single-crystal silicon substrate with an insulating layer sandwiched between. Depressions are formed in the surface regions of the single-crystal silicon substrate where no stationary parts are present and the movable parts are positioned above the depressions. The depressions form gaps large enough to prevent foreign bodies from causing shorts and malfunctioning of the movable parts.

Claims

1. A microminiature moving device comprising:

stationary parts formed of a single-crystal silicon layer of a silicon-on-insulator (SOI) wafer that comprises a single-crystal silicon substrate, an insulating layer on a surface of the single-crystal silicon substrate, and the single-crystal silicon layer on a surface of the insulating layer and fixed to stationary part fixing areas of the surface of said single-crystal silicon substrate by the insulating layer sandwiched therebetween, so that those surface areas except the stationary part fixing areas of the surface of the single-crystal silicon substrate are exposed;

movable elements formed of the single-crystal silicon layer of the silicon-on-insulator wafer having at least one end connected to a stationary part so as to be moveable in parallel to the surface of the single-crystal silicon substrate; and

depressions in all the exposed surface areas of the single-crystal silicon substrate, wherein;

the depressions have edges at boundaries of the depressions at the surface of the single-crystal silicon substrate and have a depth greater than the insulating layer thickness;

said movable elements are above said depressions;

the stationary parts have overhanging portions of its surface facing the substrate that overhang the depressions; and

the insulating layer sandwiched between the stationary parts and the single-crystal silicon substrate has edges that are indented from the overhanging portions of the stationary parts and from the edges of the depressions.

2. The device according to claim 1, wherein:

said stationary parts have portions located in an electrode pad forming area, and

a metal film is on top surface areas and sidewall surface areas of respective portions of the stationary parts located in the electrode pad forming area and on surface areas of the depressions between the respective portions of the stationary parts located in the electrode pad forming area.

3. The device according to claim 1, wherein:

said stationary parts have portions located in an electrode pad forming area,

an insulating film is on exposed surface areas of the single-crystal silicon layer and the single-crystal silicon substrate except window areas at top surface areas of respective portions of the stationary parts located in the electrode pad forming area, and

a metal film is in the window areas and on top surface areas and sidewall surface areas of the insulating film on the respective portions of the stationary parts located in the electrode pad forming area.

4. A microminiature moving device comprising:

stationary parts formed of a single-crystal silicon layer of a silicon-on-insulator (SOI) wafer that comprises a single-crystal silicon substrate, an insulating layer on a surface of the single-crystal silicon substrate, and the single-crystal silicon layer on a surface of the insulating layer and fixed to said single-crystal silicon substrate by the insulating layer sandwiched therebetween;

movable elements formed of the single-crystal silicon layer of the silicon-on-insulator wafer, and having at least one end connected to a stationary part so as to be moveable in parallel to the surface of the single-crystal silicon substrate; and

depressions in all exposed surface areas of the single-crystal silicon substrate where the stationary parts are not located, wherein;

the depressions have boundary edges at the surface of the single-crystal silicon substrate that are indented from underside edges of the stationary parts and have a depth greater than the insulating layer thickness;

the movable elements are above said depressions;

the stationary parts have underside marginal portions overhanging the depressions; and

the insulating layer sandwiched between the stationary parts and the single-crystal silicon substrate is indented from the underside edges of the stationary parts and further from the boundary edges of the depressions so that the single-crystal silicon substrate has marginal surface areas indented from the boundary edges of the depressions, and the underside marginal portions of the stationary parts further overhang the marginal surface areas of the single-crystal silicon substrate.

5. The device according to claim 4, wherein:

said stationary parts are electrically separated from each other and from the single-crystal silicon substrate and have portions located in an electrode pad forming area, and

a metal film is on top surface areas and sidewall surface areas of respective portions of the stationary parts located in the electrode pad forming area and on surface areas of the depressions between the respective portions of the stationary parts located in the electrode pad forming area.

6. The device according to claim 4, wherein:

said stationary parts are electrically separated from each other and from the single-crystal silicon substrate and have portions located in an electrode pad forming area,

an insulating film is on exposed surface areas of the single-crystal silicon layer and the single-crystal silicon substrate except window areas at top surface areas of respective portions of the stationary parts located in the electrode pad forming area, and

a metal film is in the window areas and on the top surface areas and sidewall surface areas of the insulating film on the respective portions of the stationary parts located in the electrode pad forming area.