Semiconductor type differential pressure measurement apparatus and method for manufacturing the same

• US 5,375,473 A
• Filed: 08/24/1993
• Issued: 12/27/1994
• Est. Priority Date: 08/17/1993
• Status: Expired due to Term

• Current Assignee: Yokogawa Electric Corporation
• Original Assignee: Yokogawa Electric Corporation
• Inventors: Nagai, Kouji, Kudo, Takahiro, Watanabe, Tetsuya, Tsukamoto, Hideo, Ikeda, Kyoichi, Fukuhara, Satoshi
• Primary Examiner(s): Chilcot, Jr., Richard E.
• Assistant Examiner(s): FELBER, JOSEPH LEON
• Application Number:
  US08/110,582
• Time in Patent Office: 490 Days
• Field of Search: 29/621.1, 338/4, 338/42, 73/720, 73/721, 73/726, 73/727, 73/706
• US Class Current: 73/720
• CPC Class Codes: G01L 19/0618 Overload protection
• CPC Class Codes: G01L 19/0636 using particle 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: G01L 9/0055 bonded on a diaphragm

Abstract

A semiconductor type differential pressure measurement apparatus is disclosed comprising a measuring diaphragm having its periphery fixed, and two measuring chambers, each having a predetermined spacing along both surfaces of the measuring diaphragm, and which detects differential pressure within allowable limits of measurement. When an overpressure is applied, the diaphragm is stopped by a wall of a measuring chamber to prevent the diaphragm from being damaged by overpressure, so that no additional mechanism is required to prevent damage from overpressure. One embodiment utilizes an additional chamber and overhang to reduce overpressure. Another embodiment utilizes a measuring chamber having the two sides of the diaphragm exposed to the ambient to eliminate need for a pressure resistant casing. In a further embodiment, injected impurities serve as a terminal.

Claims

1. A semiconductor type differential pressure measurement apparatus comprising

a first chamber defined by a predetermined space provided between a silicon substrate and a diaphragm formed on said silicon substrate;

a first communicating hole provided on said silicon substrate, one end thereof communicating with said first chamber;

a concave portion provided on said diaphragm on a side thereof opposite that on which said first chamber is provided;

a second chamber provided on said silicon substrate with an overhang, said second chamber communicating with said concave portion and mounted in a ring-like manner around said diaphragm except at said first communicating hole;

a second communicating hole provided on said silicon substrate, one end thereof communicating with said overhang;

a strain detector element provided on said diaphragm on a side thereof on which said concave portion is provided; and

a support substrate having one surface thereof joined with a surface of said silicon substrate having said concave portion provided thereon, said support substrate together with said concave portion defining said second chamber.

2. The apparatus of claim 1, wherein said support substrate comprises heat resistant glass.

3. The apparatus of claim 1, wherein said support substrate comprises silicon.

4. The apparatus of claim 1, wherein said support substrate comprises polysilicon.

5. The apparatus of claim 1, further comprising

a connection comprising a conductor and formed by introducing impurities into said one surface of said support substrate whereat is joined said silicon substrate and said support substrate, said connection being connected to said strain detector element at one end thereof;

a contact provided on a surface of said silicon substrate and connected to said connection at one end thereof; and

a groove formed on said silicon substrate in the vicinity of said contact, said groove absorbing undesired force generated at the contact portion between said silicon substrate and said contact.

6. The apparatus of claim 1, further comprising

a filter provided at an end of each of said first and second communicating holes, said filter having a depth dimension of d, said dimension d being sufficiently small so as to satisfy the relation d≦

(A-B), wherein A represents the depth spacing of said first chamber and B represents the displacement of said diaphragm.

7. A semiconductor type differential pressure measurement apparatus comprising

a first chamber defined by a predetermined space provided between a silicon substrate and a diaphragm formed on said silicon substrate;

a first communicating hole provided on said silicon substrate, one end thereof communicating with said first chamber;

a concave portion provided on said diaphragm on a side thereof opposite that on which said first chamber is provided;

a second chamber provided on said silicon substrate with an overhang, said second chamber communicating with said concave portion and mounted in a ring-like manner around said diaphragm except at said first communicating hole;

a second communicating hole provided on said silicon substrate, one end thereof communicating with said overhang;

a support substrate having one surface thereof joined with a surface of said silicon substrate having said concave portion provided thereon, said support substrate together with said concave portion defining said second chamber;

a first strain detector means located on an edge portion of said diaphragm on a side thereof on which said concave portion is provided;

a second strain detector element located on said diaphragm on a side thereof on which said concave portion is provided and at a position slightly offset from a center of said diaphragm, said second strain detector element being located in such a manner that said second strain detector element outputs, at least within an allowable range of measurement, a reverse phase signal with respect to the output signal of said first strain detector element, providing a differential signal of output signals from said first and second strain detector elements which behaves as a single valued function of applied pressure; and

means for detecting a signal which determines whether or not an overpressure is applied by detecting the differential of the output signals from said first and second strain detector elements.