Structure of the sensing element of a platinum resistance thermometer and method for manufacturing the same

• US 6,004,471 A
• Filed: 02/05/1998
• Issued: 12/21/1999
• Est. Priority Date: 02/05/1998
• Status: Expired due to Term

• Current Assignee: Opto Tech Corporation (OptoTech Corp.)
• Original Assignee: Opto Tech Corporation (OptoTech Corp.)
• Inventors: Chuang, Feng-Ju
• Primary Examiner(s): Gulakowski, Randy
• Assistant Examiner(s): OLSEN, ALLAN W
• Application Number:
  US09/019,434
• Time in Patent Office: 684 Days
• Field of Search: 216/16, 216/39, 216/41, 29/610.1, 29/620, 438/702, 374/114, 338/25, 427/101, 427/117, 427/118, 427/123, 427/124, 427/125
• US Class Current: 216/16
• CPC Class Codes: H01C 17/075 by thin film techniques H01C17/20 takes precedence
• CPC Class Codes: H01C 7/021 formed as one or more layers or coatings
• CPC Class Codes: H01C 7/22 Elongated resistive element being bent or curved, e.g. sinusoidal, helical
• CPC Class Codes: Y10T 29/49099 Coating resistive material on a base

Abstract

The structure of the sensing element of a platinum resistance thermometer and method for manufacturing the same, in which the silicon wafer is used as a substrate. A silicon substrate is etched to form a desired wiring pattern, then a silicon dioxide layer is grown as a layer of thermal oxide on the silicon substrate by heating the etched substrate in an oxygen-containing atmosphere. After a platinum film is deposited onto the surface of the silicon dioxide layer, the platinum-coated substrate is subject to gentle polishing. The platinum membrane outside the etched groove is easily detached while the platinum layer inside the etched groove remains attached. Thus a platinum circuit with a desired circuit pattern is formed on the substrate. After heat treatment in a temperature range of 750° C.˜ 1500° C. and further processing, the sensing element of a platinum resistance thermometer is obtained. The platinum circuit thus formed is submerged in an groove and has a substantially bulk structure.

Claims

1. A method for forming the sensing element of a platinum resistance thermometer, comprising the steps of:

forming a mask on the surface of a substrate, the pattern of said mask being substantially identical to the negative pattern of the platinum circuit of said sensing element;

etching said substrate through the opening of said mask to form a groove on the surface of said substrate, the pattern of said groove being substantially identical to the positive pattern of said platinum circuit of said sensing element;

removing said mask from said substrate completely;

forming a dielectric layer on the surface of said etched substrate and said groove, said dielectric layer being divided into a concave portion located on said groove and a smooth portion located on the surface of said substrate;

depositing a layer of platinum film on the surface of said dielectric layer, said platinum film being divided into a first platinum layer located on said concave portion within said groove and a second platinum layer located on said smooth portion on the surface of said substrate; and

polishing said substrate having said dielectric layer and said platinum film thereon to remove said second platinum layer, said first platinum layer remaining attached to said concave portion, thereby forms said platinum circuit of said sensing element.

2. The method for forming the sensing element of a platinum resistance thermometer as described in claim 1, wherein said substrate is a silicon substrate.

3. The method for forming the sensing element of a platinum resistance thermometer as described in claim 2, wherein said dielectric layer is a silicon dioxide layer or a silicon nitride layer.

4. The method for forming the sensing element of a platinum resistance thermometer as described in claim 1, wherein said groove is a V-shaped groove.

5. A method for forming the sensing element of a platinum resistance thermometer, comprising the steps of:

forming a mask on the surface of a dielectric substrate, the pattern of said mask being substantially identical to the negative pattern of the platinum circuit of said sensing element;

etching said dielectric substrate through the opening of said mask to form a groove on the surface of said dielectric substrate, the pattern of said groove being substantially identical to the positive pattern of said platinum circuit of said sensing element;

the surface of said dielectric substrate being divided into a concave portion located on said groove and a smooth portion located on the original surface of said dielectric substrate;

removing said mask from said substrate completely;

depositing a layer of platinum film on the surface of said dielectric substrate, said platinum film being divided into a first platinum layer located on said concave portion within said groove and a second platinum layer located on said smooth portion on the original surface of said dielectric substrate; and

polishing said dielectric substrate having said platinum film thereon to remove said second platinum layer, said first platinum layer remaining attached to said concave portion, thereby forms said platinum circuit of said sensing element.

6. The method for forming the sensing element of a platinum resistance thermometer as described in claim 5, wherein said groove is a V-shaped groove.