Semiconductor pressure sensor

Patent metadata

Field	Value
Publication number	US-9689767-B2
Application number	US-201414650505-A
Country	US
Kind code	B2
Filing date	Dec 10, 2014
Priority date	Dec 11, 2013
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

A semiconductor pressure sensor for measuring an external pressure exerted on the sensor, comprises a membrane, and a bridge comprising a first and a second resistor pair, arranged on a first resp. second side portion of the membrane. The first resistor pair comprises a first and a second resistor (R 1 , R 2 ) comprising elongated piezo-resistive strips connected in series, and located closely together, such that R 1 and R 2 have substantially the same temperature. The sensor has a reduced sensitivity to: a temperature gradient over the membrane, and optionally also a non-uniform stress gradient caused by packaging and a inhomogeneous disturbing electric field perpendicular to the sensor. The piezo-resistive strips of the first and second resistor may be oriented in orthogonal directions of maximum piezo-resistive coefficients. A second bridge may be added outside the membrane, for compensating for package pressure.

First claim

The invention claimed is:

1. A semiconductor pressure sensor for measuring an external pressure exerted on the sensor, comprising:
a membrane as part of a semiconductor substrate for being deformed due to the external pressure, having a membrane edge and a membrane thickness;
a first bridge circuit comprising a first resistor pair located on or adjacent to a first side portion of the membrane, and a second resistor pair located on or adjacent to a second side portion of the membrane;
the first resistor pair comprising a first resistor connected between a first bias node and a first output node, and a second resistor connected between the first output node and a second bias node;
the second resistor pair comprising a third resistor connected between the first bias node and a second output node, and a fourth resistor connected between the second output node and the second bias node;
at least one of the first and second and third and fourth resistor comprising one or more elongated piezo-resistive strips arranged for measuring deformation of the membrane due to the external pressure to be measured;
wherein the ratio of a largest distance between a point of the first resistor and a point of the second resistor, and a largest dimension of the membrane is less than 50%;
and wherein the ratio of a largest distance between a point of the third resistor and a point of the fourth resistor, and a largest dimension of the membrane is less than 50%,
and
wherein the second side portion is located at substantially 90° angular distance from the first side portion as measured from a center of the membrane, and the elongated piezo-resistive strips of the first resistor are oriented parallel to the elongated piezo-resistive strips of the third resistor; or
wherein the second side portion is located at substantially 180° angular distance from the first side portion as measured from a center of the membrane, and the elongated piezo-resistive strips of the first resistor are oriented orthogonal to the elongated piezo-resistive strips of the third resistor.

2. The semiconductor pressure sensor of claim 1 , wherein
at least two of the first, second, third and fourth resistors comprise one or more elongated piezo-resistive strips arranged for measuring deformation of the membrane due to the external pressure to be measured;
whereby the one or more piezo-resistive strips are oriented such as to cooperate to the imbalance of the bridge when a pressure is exerted on the membrane.

3. The semiconductor pressure sensor of claim 2 , wherein
at least three of the first, second, third and fourth resistors comprise one or more elongated piezo-resistive strips arranged for measuring deformation of the membrane due to the external pressure to be measured;
whereby the one or more piezo-resistive strips are oriented such as to cooperate to the imbalance of the bridge when a pressure is exerted on the membrane.

4. The semiconductor pressure sensor of claim 3 , wherein
each of the first, second, third and fourth resistors comprises one or more elongated piezo-resistive strips arranged for measuring deformation of the membrane due to the external pressure to be measured;
whereby the one or more piezo-resistive strips are oriented such as to cooperate to the imbalance of the bridge when a pressure is exerted on the membrane.

5. The semiconductor pressure sensor according to claim 1 ,
wherein the at least one resistor comprising one or more elongated piezo-resistive strips, comprises at least two piezo-resistive strips connected in series.

6. The semiconductor pressure sensor according to claim 1 , wherein the second side portion is located substantially or precisely at 90° angular distance from the first side portion, as measured from a center of the membrane.

7. The semiconductor pressure sensor according to claim 1 ,
wherein the ratio of a largest distance between a point of the first resistor and a point of the second resistor, and a largest dimension of the membrane is less than 25%;
and wherein the ratio of a largest distance between a point of the third resistor and a point of the fourth resistor, and a largest dimension of the membrane is less than 25%.

8. The semiconductor pressure sensor according to claim 1 , wherein
the membrane is substantially square, and the largest dimension is the width of the square, the first side portion is a first side of the square, and the second side portion is a second side of the square adjacent the first side; and
the first resistor and the second resistor are arranged substantially in the middle of the first side of the square;
the third resistor and the fourth resistor are arranged substantially in the middle of the second side of the square.

9. The semiconductor pressure sensor according to claim 1 , wherein
the membrane is substantially circular, and the largest dimension is the diameter of the circle; or
the membrane is substantially rectangular, and the largest dimension is the larger of the length and the width of the rectangle; or
the membrane is substantially elliptical, and the largest dimension is the larger of the first and the second axis of the ellipse;
the membrane is substantially octagonal, and the largest dimension is the distance between opposite sides of the octagonal.

10. The semiconductor pressure sensor according to claim 1 , wherein
the ratio of the resistance of the first resistor and the resistance of the second resistor lies in the range of 50% to 200%; and
the ratio of the resistance of the third resistor and the resistance of the fourth resistor lies in the range of 50% to 200%.

11. The semiconductor pressure sensor according to claim 1 , wherein:
the second side portion is located at 90° angular distance from the first side portion as measured from a center of the membrane, and
the elongated piezo-resistive strips of the first resistor are oriented orthogonal to the elongated piezo-resistive strips of the second resistor; and
the elongated piezo-resistive strips of the third resistor are oriented orthogonal to the elongated piezo-resistive strips of the fourth resistor; and
the elongated piezo-resistive strips of the first resistor are oriented parallel to the elongated piezo-resistive strips of the third resistor.

12. The semiconductor pressure sensor according to claim 1 , wherein:
the second side portion is located at 180° angular distance from the first side portion as measured from a center of the membrane, and
the elongated piezo-resistive strips of the first resistor are oriented orthogonal to the elongated piezo-resistive strips of the second resistor; and
the elongated piezo-resistive strips of the third resistor are oriented orthogonal to the elongated piezo-resistive strips of the fourth resistor; and
the elongated piezo-resistive strips of the first resistor are oriented orthogonal to the elongated piezo-resistive strips of the third resistor.

13. The semiconductor pressure sensor according to claim 1 , arranged on a CMOS wafer, whereby the membrane is located in an plane, and at least one of the piezo-resistive elements is oriented in the <110> direction.

14. A semiconductor device comprising a semiconductor pressure sensor according to claim 1 .

15. A semiconductor pressure sensor for measuring an external pressure exerted on the sensor, comprising:
a membrane as part of a semiconductor substrate for being deformed due to the external pressure, having a membrane edge and a membrane thickness;
a first bridge circuit comprising a first resistor pair located on or adjacent to a first side portion of the membrane, and a sec

Assignees

• Melexis Technologies Nv

Inventors

• Van Der Wiel Appolonius Jacobus

Classifications

• G01L19/04

  Means for compensating for effects of changes of temperature {, i.e. other than electric compensation} · CPC title

• G01L9/0055 Primary

  bonded on a diaphragm · CPC title

• G01L9/065 Primary

  with temperature compensating means (non electric temperature compensating means G01L19/04) · CPC title

• G01L9/0054

  integral with a semiconducting diaphragm · CPC title

• G01L9/0042 Primary

  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) · CPC title