TRANSDUCER FORMED IN PERIPHERALLY SUPPORTED THIN SEMICONDUCTOR WEB

• US 3,758,830 A
• Filed: 04/10/1972
• Issued: 09/11/1973
• Est. Priority Date: 04/10/1972
• Status: Expired due to Term

• Current Assignee: Weldon H. Jackson
• Original Assignee: Weldon H. Jackson
• Inventors: Jackson, Weldon H.
• Primary Examiner(s): Huckert, John W.
• Assistant Examiner(s): James, Andrew J.
• Application Number:
  US05/242,606
• Time in Patent Office: 519 Days
• Field of Search: 317/235,26,29,29.1 310/4 73/88SD
• US Class Current: 257/419
• CPC Class Codes: G01K 7/02 using thermoelectric elements, e.g. thermocouples
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm
• CPC Class Codes: H01L 23/36 Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks H01L23/28, H01L23/40, H01L23/42, H01L23/44, H01L23/46 take precedence; heating H01L23/345
• CPC Class Codes: H01L 24/01 Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
• CPC Class Codes: H01L 29/00 Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor H01L31/00 - H01L33/00, H10K10/00, H10N take precedence; details other than of semiconductor bodies or of electrodes thereof H01L23/00; devices consisting of a plurality of solid state components formed in or on a common substrate H01L27/00
• CPC Class Codes: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: Y10S 148/051 Etching
• CPC Class Codes: Y10S 148/097 Lattice strain and defects
• CPC Class Codes: Y10S 148/136 Resistors
• CPC Class Codes: Y10T 29/49103 Strain gauge making

Abstract

A thin web supported by a peripheral frame is formed from a single crystal of silicon, the web and frame being of opposite conductivity types. A lower resistivity region is diffused into the web, and the web is covered by an insulating layer having holes through which conductors are deposited in contact with each end of the diffused region. The resulting transducer can be used as a thermocouple or strain gage. For use as a thermocouple, one of the junctions between the diffused region and a conductor is situated near the center portion of the web. The diffused region comprises one leg of the thermocouple, and one of the conductors functions as the other leg. The frame acts as a heat sink relative to the center portion of the web, making the junction near the center portion a hot junction and the junction near the frame a cold junction. For use as a diaphragm type strain gage the diffused region is made to transverse most of the web. The frame serves as a mounting base that is integral with the strain gage. The resistance of the diffused region changes in proportion to the change of the dimensions of the diffused region that result from the application of a force normal to the plane of the web.

Claims

1. A transducer comprising:

a single-crystal, semiconductor support member having a frame portion of a first conductivity type and a web portion, thinner than the frame portion, of a second conductivity type;

a sensing region of lower resistivity than the web portion formed in the web portion;

an insulating layer substantially covering the web portion;

a first conductor supported on the insulating layer and making electrical contact with a first portion of the sensing region through a first opening in the insulating layer; and

a second conductr supported on the insulating layer and making electrical contact with a second portion of the sensing region through a second opening in the insulating layer.

2. A transducer as in claim 1 including a third conductor supported on the insulating layer wherein:

the frame portion is peripheral;

the first portion of the sensing region is near the center of the web portion;

the sensing region forms a first leg of the thermocouple;

the first conductor forms a second leg of the thermocouple;

the contact between the first portion of the sensing region and the first conductor forms a first thermocouple junction; and

the third conductor makes contact with the first conductor near the frame portion, and the second portion of the sensing region makes contact with the second conductor near the frame portion, the contact between the second portion of the sensing region and the second conductor and between the first and third metals forming second thermocouple junctions.

3. A transducer as in claim 2 wherein the doping of the sensing region is non-uniform along a direction normal to the surface of the web portion.

4. A transducer as in claim 3 wherein:

the frame portion is P-conductivity type; and

the web portion and the sensing region are N-conductivity type.

5. A transducer as in claim 1 wherein:

the frame portion is peripheral;

the contact between the first conductor and the first portion of the sensing region is near a first segment of the frame portion; and

the contact between the second conductor and the second portion of the sensing region is near a second segment of the frame portion, substantially opposite the first segment.

6. A transducer as in claim 5 wherein the doping of the sensing region is non-uniform along a direction normal to the surface of the web portion.

7. A transducer as in claim 1 wherein:

the first portion of the sensing region is a first conductivity type;

the second portion of the sensing region is a second conductivity type; and

a rectifying junction is formed between the first and second portions of the sensing region.