PRESSURE SENSOR

• US 20080202248A1
• Filed: 02/22/2008
• Published: 08/28/2008
• Est. Priority Date: 02/28/2007
• Status: Active Grant

• Current Assignee: Azbil Corporation (Azbil BioVigilant Incorporated)
• Original Assignee: Yamatake Corporation
• Inventors: Yoneda, Masayuki, Tojo, Hirofumi, Tokuda, Tomohisa
• Granted Patent: US 7,497,126 B2
• Time in Patent Office: Days
• US Class Current: 73/721
• 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

Abstract

In a pressure sensor comprising a diaphragm formed on a portion of a chip made of semiconductor material and that senses pressure on the diaphragm by electrically converting the displacement corresponding to that pressure, the provision of the diaphragm with an aspect ratio of at least a size such that the derivative of the characteristic curve of the allowable pressure resistance of the pressure sensor, defined by setting the aspect ratio obtained by dividing the length of one side of the diaphragm by the thickness of the diaphragm as the horizontal axis and by setting the allowable pressure resistance of the pressure sensor as the vertical axis, becomes nearly zero, enables a pressure sensor having high sensitivity and high pressure resistance.

Claims

1. A pressure sensor comprising a diaphragm formed on a portion of a chip made of semiconductor material and sensing pressure acting on the diaphragm by electrically converting the displacement corresponding to that pressure, wherein:

the diaphragm is provided with an aspect ratio of at least a size such that the derivative of the characteristic curve of the allowable pressure resistance of the pressure sensor, defined by setting the aspect ratio obtained by dividing the length of one side of the diaphragm by the thickness of the diaphragm as the horizontal axis and by setting the allowable pressure resistance of the pressure sensor as the vertical axis, becomes nearly zero.

2. The pressure sensor cited in claim 1, wherein the diaphragm has a square shape as viewed from the side on which the pressure acts.

3. The pressure sensor cited in claim 1, wherein the diaphragm is formed from monocrystalline silicon.

4. The pressure sensor as cited in claim 1, wherein the diaphragm has a thickness of not more than 15 μ

m and the aspect ratio of at least 135.