High pressure sensor structure and method

• US 5,581,226 A
• Filed: 11/02/1994
• Issued: 12/03/1996
• Est. Priority Date: 11/02/1994
• Status: Expired due to Fees

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Shah, Mahesh
• Primary Examiner(s): Walberg, Teresa J.
• Assistant Examiner(s): EASTHOM, KARL D
• Application Number:
  US08/333,167
• Time in Patent Office: 762 Days
• Field of Search: 338/36, 338/42, 338/2, 338/4, 338/5, 73/724, 73/721, 73/722, 73/723
• US Class Current: 338/42
• CPC Class Codes: G01L 19/0084 to the outside of the housing other details about the housing see G01L19/14
• CPC Class Codes: G01L 19/143 Two part housings
• CPC Class Codes: G01L 19/147 Details about the mounting of the sensor to support or covering means
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

A high pressure sensor structure (11, 111, 211) includes a housing (12, 112, 212) having an upper cavity portion (13, 113, 213) and a lower cavity portion (16, 116, 216). A diaphragm (18, 118, 218) separates the upper cavity portion (13, 113, 213) from the lower cavity portion (16, 116, 216). A semiconductor chip (26, 126, 226) is attached to the upper surface of the diaphragm (18, 118, 218) within the upper cavity portion (13, 113, 213). The diaphragm (18, 118, 218) has a thickness (21, 121, 221) and an exposed width (23, 123, 223) such that the semiconductor chip (26, 126, 226) generates a measurable output signal when the lower surface of the diaphragm (18, 118, 218) is exposed to a high pressure environment.

Claims

1. A high pressure sensor structure comprising:

a housing having an upper cavity, and a lower cavity;

a pressure introducing portion separating the upper cavity from the lower cavity, the pressure introducing portion having a thickness, an exposed width, an upper surface, and a lower surface, wherein the lower cavity has an opening, and wherein the thickness is substantially uniform across the exposed width;

a sensing chip attached to the upper surface of the pressure introducing portion within the upper cavity;

a conductive connective structure coupled to the sensing chip; and

an enclosure covering the upper cavity.

2. The structure of claim 1 wherein the housing comprises an injection molded plastic.

3. The structure of claim 2 wherein the pressure introducing portion comprises plastic, and wherein the pressure introducing portion is integral with the housing.

4. The structure of claim 3 wherein the exposed width is in a range from approximately 6.0 to 7.5 mm, and wherein the thickness is in a range from approximately 1.0 to 1.5 mm, such that the high pressure sensor structure measures pressures up to approximately 14,000 kPa.

5. The structure of claim 2 wherein the pressure introducing portion comprises a metal insert.

6. The structure of claim 5 wherein the exposed width is in a range from approximately 6.0 to 7.5 mm, and wherein the thickness is in a range from approximately 0.5 to 1.0 mm, such that the high pressure sensor structure measures pressures up to approximately 14,000 kPa.

7. The structure of claim 1 wherein the housing comprises a ceramic.

8. The structure of claim 7 wherein the pressure introducing portion comprises a metal, and wherein the pressure introducing portion is bonded to the housing.

9. The structure of claim 8 wherein the exposed width is in a range from approximately 6.0 to 7.5 mm, and wherein the thickness is in a range from approximately 0.5 to 1.0 mm, such that the high pressure sensor structure measures pressures up to approximately 14,000 kPa.

10. The structure of claim 1 wherein the sensing chip includes a plurality of bonding pads, and wherein the conductive connective structure includes a plurality of wire bonds and a plurality of conductive leads, the plurality of wire bonds electrically connecting the plurality of bonding pads to the plurality of conductive leads.

11. The structure of claim 10 wherein at least a portion of the plurality of conductive leads is integral with the housing.

12. The structure of claim 10 further comprising a protective layer covering at least the sensing chip and the plurality of wire bonds.

13. A device for sensing high pressures having a diaphragm external to a semiconductor chip comprising:

a hollow containing structure having an upper portion and a lower portion, the lower portion open at one end and having an outer surface;

a diaphragm within the hollow containing structure separating the upper portion from the lower portion, the diaphragm having a thickness, an upper surface, a lower surface, and an exposed width, the thickness substantially uniform across the exposed width, wherein the hollow containing structure and the diaphragm comprise an injection molded plastic, and wherein the diaphragm is integral with the hollow containing structure;

a semiconductor chip attached to the upper surface of the diaphragm within the upper portion, the semiconductor chip having a plurality of bonding pads;

a plurality of conductive leads, each having a bond post end and an external connecting end;

a plurality of conductive wires electrically connecting the plurality of bonding pads to the plurality of conductive leads; and

a lid covering the upper portion.

14. The device of claim 13 further comprising a protective layer covering at least the semiconductor chip and the plurality of conductive wires.

15. The device of claim 13 wherein the thickness is in a range from approximately 6.0 to 7.5 mm, and wherein the exposed width is in a range from approximately 1.0 to 1.5 mm.

16. The device of claim 13 wherein the outer surface of the lower portion is threaded.

17. A method for making a high pressure sensor structure comprising the steps of:

providing a housing having an upper cavity, a lower cavity, a pressure introducing portion separating the upper cavity from the lower cavity, and a conductive connective structure, the pressure introducing portion having a thickness, an exposed width, an upper surface, and a lower surface, the lower cavity having an opening for exposing the lower surface to a high pressure media, and wherein the thickness is substantially uniform across the exposed width;

attaching a semiconductor transducer to the upper surface of the pressure introducing portion within the upper cavity;

connecting the semiconductor transducer to the conductive connective structure; and

enclosing the upper cavity.

18. The method of claim 17 wherein the step of providing the housing includes providing an injection molded plastic housing, and wherein the pressure introducing portion comprises an injection molded plastic, and wherein the pressure introducing portion is integral with the housing.

19. The method of claim 18 wherein the step of providing the injection molded plastic housing includes providing the injection molded plastic housing wherein the thickness of the pressure introducing portion is in a range from 6.0 to 7.5 mm, and wherein the exposed width of the pressure introducing portion is in a range from 1.0 to 1.5 mm.