US 6,772,632 B2Granted

Acceleration sensor and manufacturing method for the same

AssigneeWacoh Corporation

InventorKazuhiro Okada

Life of this patent

Estimating the term…

Loading patent…

Abstract

The present invention easily achieves an accurate control structure for limiting displacement of a weight. An SOI substrate with a trilaminar structure including a silicon layer, a silicon oxide layer, and a silicon layer is prepared, and slits are opened by applying induced coupling plasma etching which can selectively remove only silicon from the upper side. Then, the same etching is applied from the lower side to form grooves, whereby the lower silicon layer is separated into a weight and a pedestal. Next, the structure is immersed in an etchant which can selectively remove only silicon oxide, whereby the vicinities of exposed portions of the silicon oxide layer are removed to form joint layers. A glass substrate is joined to the bottom surface of the pedestal. Piezo resistor elements are formed on the upper surface of the silicon layer to detect bending. The degree of freedom of upward displacements of the weight is accurately set based on the thickness of the joint layer.

Claims21

Dependent claims

An acceleration sensor comprising:

a substrate layer having a displacing section provided at a central portion, a fixed section provided around said displacing section, and a connecting portion for connecting said displacing section to said fixed section so that said displacing section can displace;
a weight disposed under said substrate layer, said weight including an upper surface peripheral portion that opposes a control surface formed on a lower surface of an inner part of said fixed section;
a pedestal which is disposed so as to surround said weight and supports and fixes said fixed section from below;
a weight joint layer which is interposed in a region other than said upper surface peripheral portion in a space between said weight and said substrate layer and is made of a material different from that of said weight and said substrate layer, and connects said weight to a lower surface of said displacing section;
and
a displacement detector for detecting a displacement of said displacing section;
wherein
when an acceleration is applied to said weight, said displacing section displaces with respect to said fixed section due to bending of said connecting portion, and a thickness of said weight joint layer is set so that said upper surface peripheral portion comes into contact with said control surface to control displacement when a degree of a predetermined directional component of an applied acceleration exceeds a predetermined tolerance.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/419,610Filed 21 Apr 2003
Priority: JP 2002-13659613 May 2002
Published: US 2003/0209075 A113 Nov 2003
Granted: 10 Aug 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification16 codes

G01P 15/125
With conversion into electric or magnetic values: by capacitive pick-up
B81B 3/0062
Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes: devices moving in two or more dimensions, i.e.…
G01P 15/08
By making use of inertia forces using solid seismic masses: with conversion into electric or magnetic values
G01P 15/0802
With conversion into electric or magnetic values: details