Offset-free resistor geometry for use in piezo-resistive pressure sensor

• US 5,812,047 A
• Filed: 02/18/1997
• Issued: 09/22/1998
• Est. Priority Date: 02/18/1997
• Status: Expired due to Term

• Current Assignee: Silicon Microstructures, Inc (TE Connectivity Limited)
• Original Assignee: Exar Corporation (Maxlinear Incorporated)
• Inventors: van Kampen, Robertus P.
• Primary Examiner(s): Walberg, Teresa J.
• Assistant Examiner(s): EASTHOM, KARL D
• Application Number:
  US08/800,437
• Time in Patent Office: 581 Days
• Field of Search: 338/2, 338/4, 338/36, 338/42, 73/721, 73/727, 257/419
• US Class Current: 338/4
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm

Abstract

An improved resistor and connection region structure in which the geometries of the connection regions for a pair of radial resistors correspond to the connection region geometries for a pair of tangential resistors, thus inherently eliminating the need for varying connection regions to compensate for offset. In particular, the radial resistors are formed by placing two legs in parallel with each other and connecting those legs in series on opposite sides of the membrane, with the connection region on the interior of the membrane. The tangential resistors, on the other hand, are formed on the opposite sides by placing two legs in series with each other and connecting those legs in series, with an interior connection region connecting them.

Claims

1. A piezo-resistive pressure sensor comprising;

a substrate having a membrane;

first and second pairs of electrically serially connected radial resistors formed geometrically in parallel on first and second opposite sides of said membrane,

each of said first and second pairs having first ends which are closest to a center of said membrane and are connected by a first low-resistance connection region,

each of said first and second pairs having second ends, located closest to said substrate, which are connected to a conductive interconnect layer, located on said substrate, with a pair of second low-resistance connection regions; and

third and fourth pairs of electrically serially connected tangental resistors formed geometrically in series on third and fourth opposite sides of said membrane,

each of said third and fourth pairs of tangential resistors having first ends located closest to each other which are connected by third low-resistance contact regions,

each of said third and fourth pairs of tangential resistors having second ends, located furthest from each other, which are connected to said conductive interconnect layer, located on said substrate, by a pair of fourth low-resistance connection regions;

wherein said connection regions are non-square rectangles, each having a length and width, and the width and total length of said first low-resistance connection region and said pair of second low-resistance connection regions equals the width and total length of said third low-resistance connection region and said pair of fourth low-resistance connection regions, said connection regions extending over a border from said substrate to said membrane.

2. A piezo-resistive pressure sensor comprising:

a substrate having a membrane;

first and second pairs of electrically serially connected radial resistors formed geometrically in parallel on first and second opposite sides of said membrane,

each of said first and second pairs having first ends which are closest to a center of said membrane and are connected by a first low-resistance connection region,

each of said first and second pairs having second ends, located closest to said substrate, which are connected to a conductive interconnect layer, located on said substrate, with a pair of second low-resistance connection regions; and

third and fourth pairs of electrically serially connected tangential resistors formed geometrically in series on third and fourth opposite sides of said membrane,

each of said third and fourth pairs of tangential resistors having first ends located closest to each other which are connected by third low-resistance contact regions,

each of said third and fourth pairs of tangential resistors having seconds ends, located furthest from each other, which are connected to said conductive interconnect layer, located on said substrate, by a pair of fourth low-resistance connection regions;

wherein said resistors and said connection regions are rectangular, each having two long and two short sides, wherein said connection regions are wider than said resistors, and wherein said first and second pairs of radial resistors are connected to a first long side of said first low-resistance connection region, each a first distance from a corner of said first low-resistance connection region and said third and fourth pairs of tangential resistors are connected to first and second long sides, respectively, of said fourth low-resistance connection regions, each a second distance equal to said first distance from a corner of said fourth low-resistance connection region.

3. A piezo-resistive pressure sensor comprising:

a substrate having a membrane;

first and second pairs of electrically serially connected radial resistors formed geometrically in parallel on first and second opposite sides of said membrane,

each of said first and second pairs having first ends which are closest to a center of said membrane and are connected by a first low-resistance connection region,

each of said first and second pairs having second ends, located closest to said substrate, which are connected to a conductive interconnect layer, located on said substrate, with a pair of second low-resistance connection regions; and

third and fourth pairs of electrically serially connected tangential resistors formed geometrically in series on third and fourth opposite sides of said membrane,

each of said third and fourth pairs of tangential resistors having first ends located closest to each other which are connected by third low-resistance contact regions,

each of said third and fourth pairs of tangential resistors having second ends, located furthest from each other, which are connected to said conductive interconnect layer, located on said substrate, by a pair of fourth low-resistance connection regions;

wherein said resistors and said connection regions are rectangular, each having two long and two short sides, wherein said connection regions are wider than said resistors, and wherein said first and second pairs of radial resistors are each connected to a short side, respectively, of said second low-resistance connection regions a first distance from a corner of said respective second low-resistance connection regions, and said third and fourth pairs of tangential resistors are each connected to a short side, respectively, of said third low-resistance connection regions, a second distance equal to said first distance from a corner of said respective third low-resistance connection regions.

4. A piezo-resistive pressure sensor comprising:

a substrate having a membrane;

first and second pairs of rectangular radial resistors formed geometrically in parallel on first and second opposite sides of said membrane,

each of said first and second pairs having first ends closest to a center of said membrane which are connected by a first rectangular low-resistance connection region,

each of said first and second pairs having second ends, closest to said substrate, which are directly connected without intervening conductors to a conductive interconnect layer, located on said substrate, with a pair of second low-resistance rectangular connection regions;

third and fourth pairs of rectangular tangential resistors formed geometrically in series on third and fourth opposite sides of said membrane,

each of said third and fourth pairs of tangential resistors having first ends located closest to each other which are connected by third low-resistance rectangular connection regions,

each of said third and fourth pairs of tangential resistors having second ends without intervening conductors located furthest from each other, which are directly connected to said conductive interconnect layer, located on said substrate, by a pair of fourth low-resistance rectangular connection regions;

wherein the width and total length of said first and second pairs of radial resistors equals the width and total length of said third and fourth pairs of tangential resistors;

wherein the width and total length of said first low-resistance connection region and said pair of second low-resistance connection regions equals the width and total length of said third low-resistance connection region and said pair of fourth low-resistance connection regions;

a plurality of contact regions, each contact region being formed on a portion of said substrate located off said membrane and being connected by said interconnect layer to

said pair of second low-resistance connection regions and said pair of fourth low-resistance connection regions; and

a plurality of conductive lines connected to said contact regions for connecting said resistors in a Wheatstone bridge arrangement.

5. The sensor of claim 4 wherein said resistors and said connection regions are rectangular, each having two long and two short sides, wherein said connection regions are wider than said resistors, and wherein said first and second pairs of radial resistors are connected to a first long side of said first low-resistance connection region, each a first distance from a corner of said first low-resistance connection region and said third and fourth pairs of tangential resistors are connected to first and second long sides, respectively, of said fourth low-resistance connection regions, each a second distance equal to said first distance from a corner of said fourth low-resistance connection region.

6. The sensor of claim 4 wherein said resistors and said connection regions are rectangular, each having two long and two short sides, wherein said connection regions are wider than said resistors, and wherein said first and second pairs of radial resistors are each connected to a short side, respectively, of said second low-resistance connection regions a first distance from a corner of said respective second low-resistance connection regions, and said third and fourth pairs of tangential resistors are each connected to a short side, respectively, of said third low-resistance connection regions, a second distance equal to said first distance from a corner of said respective third low-resistance connection regions.