Semiconductor sensor and method of manufacturing the same

• US 20080202249A1
• Filed: 01/29/2008
• Published: 08/28/2008
• Est. Priority Date: 01/30/2007
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kawasaki, Eishi, Isobe, Yoshihiko, Yokura, Hisanori
• Granted Patent: US 7,644,623 B2
• Time in Patent Office: Days
• US Class Current: 73/726
• CPC Class Codes: G01K 5/52 with electrical conversion means for final indication
• CPC Class Codes: G01L 1/2293 of the semi-conductor type semi-conductor devices controllable by variations of applied mechanical force H01L29/84
• CPC Class Codes: G01L 9/0055 bonded on a diaphragm
• CPC Class Codes: H01L 2224/02166 Collar structures
• CPC Class Codes: Y10T 29/49103 Strain gauge making

Abstract

A semiconductor pressure sensing apparatus includes a metallic stem having a diaphragm and a semiconductor sensor bonded to the diaphragm. The semiconductor sensor includes a gauge section and first and second bonding pads. The gauge section is configured to be deformed according to a deformation of the diaphragm. The first and second bonding pads are respectively connected to different positions of the gauge section so that an electrical resistance between the first and second bonding pads can change with a change in the deformation of the diaphragm. The gauge section is formed to a semiconductor layer of an silicon-on-insulator substrate. The semiconductor sensor is directly bonded to the diaphragm by activating contact surfaces between the semiconductor sensor and the diaphragm.

Claims

1. A semiconductor sensor comprising:

an insulating layer;

a semiconductor layer disposed on the insulating layer, the semiconductor layer having at least one gauge section configured to be deformed according to an amount of physical quantity applied thereto; and

first and second bonding pads respectively connected to different positions of the gauge section,

wherein an electrical resistance between the first and second bonding pads changes with a change in the amount of the applied physical quantity.

2. The semiconductor sensor according to claim 1, further comprising:

a base substrate disposed under the insulating layer,

wherein the semiconductor layer, the insulating layer, and the base substrate are configured as a silicon-on-insulator substrate.

3. The semiconductor sensor according to claim 1,

wherein the semiconductor layer has an impurity concentration of about between 1×

10¹⁹ per cubic centimeter and 1×

10²¹ per cubic centimeter.

4. The semiconductor sensor according to claim 2,

wherein the semiconductor layer has a thickness of about between 1 micrometer and 2 micrometers, and

wherein the silicon-on-insulator substrate has a thickness less than about 10 micrometers.

5. The semiconductor sensor according to claim 1,

wherein the gauge section has a plurality of straight and bent portions connected to each other to form a zigzag shape.

6. The semiconductor sensor according to claim 1, further comprising:

an electrically insulating film that covers the gauge section.

7. The semiconductor sensor according to claim 6, further comprising:

a first protection film disposed on the insulating film to protect the semiconductor sensor.

8. The semiconductor sensor according to claim 7, further comprising:

a second protection film disposed between the insulating film and the first protection film to protect the gauge section.

9. The semiconductor sensor according to claim 1,

wherein the semiconductor layer having a plurality of gauge sections arranged in series.

10. The semiconductor sensor according to claim 1,

wherein the physical quantity is pressure.

11. The semiconductor sensor according to claim 1,

wherein the physical quantity is a temperature.

12. A method of manufacturing a semiconductor sensor comprising:

(a) preparing a silicon-on-insulator substrate that includes a base substrate, a buried insulating layer disposed on the base substrate, and a semiconductor layer disposed on the insulating layer;

(b) forming at least one gauge section to the semiconductor layer in such a manner that the gauge section is strained according to an amount of physical quantity applied thereto; and

(c) connecting first and second bonding pads to different positions of the gauge section.

13. The method according to claim 12,

wherein in step (a) the semiconductor layer has an impurity concentration of about between 1×

10¹⁹ cubic centimeter and 1×

10²¹ cubic centimeter.

14. The method according to claim 12,

wherein in step (a) the semiconductor layer has a thickness of about between 1 micrometer and equal 2 micrometers, and

wherein in step (a) the silicon-on-insulator substrate has a thickness less than about 10 micrometers.

15. The method according to claim 12,

wherein in step (b) the gauge section includes a plurality of straight and bent portions connected to form a zigzag shape.

16. The method according to claim 12,

wherein in step (b) the gauge section is covered with an electrically insulating film.

17. The method according to claim 16, further comprising:

(d) forming a first protection film on the insulating film to protect the semiconductor sensor.

18. The method according to claim 17, further comprising:

(e) forming a second protection film between the insulating film and the first protection film to protect the gauge section.

19. The method according to claim 12, further comprising:

(f) eliminating the base substrate and the buried insulating layer from a back side of the silicon-on-insulator substrate.

20. The method according to claim 17, further comprising:

(g) forming a plurality of through holes extending from a top surface of the first protection film to a top surface of the buried insulating layer;

(h) wet etching a part of the buried insulating layer through the plurality of through holes; and

(i) removing a remainder of the buried insulating layer and the base substrate by using a dicing saw.

21. The method according to claim 17, further comprising:

(j) forming a plurality of through holes extending from a top surface of the first protection film to a top surface of the buried insulating layer;

(k) wet etching the buried insulating layer through the plurality of through holes.

22. The method according to claim 12, further comprising:

(l) removing the base substrate of the silicon-on-insulator substrate.

23. The method according to claim 12,

wherein in step (b) a plurality of gauge sections arranged in series is formed to the semiconductor layer.

24. The method according to claim 12,

wherein the physical quantity is pressure.

25. The method according to claim 12,

wherein the physical quantity is a temperature.

26. A pressure sensing apparatus comprising:

a housing having a pressure passageway provided with a pressure inlet port for introducing pressure into the pressure passageway;

a metallic stem having a diaphragm at a first side and an opening at a second side, the stem being placed in the pressure passageway in such a manner that the introduced pressure is applied to a back surface of the diaphragm through the opening; and

a sensor chip including a sensing section and having a front surface provided with the sensing section and a back surface directly bonded to a front surface of the diaphragm.

27. The pressure sensing apparatus according to claim 26,

wherein the front surface of the diaphragm and the back surface of the sensor chip are activated to be directly bonded together.

28. The pressure sensing apparatus according to claim 26,

wherein the sensor chip is a silicon-on-insulator substrate that has a silicon layer, an insulating layer, and a base substrate having a front surface bonded to the silicon layer through the insulating layer,

wherein a strain gauge is formed to the silicon layer and serves as the sensing section, and

wherein a back surface of the base substrate is directly bonded to the front surface of the diaphragm.

29. The pressure sensing apparatus according to claim 28,

wherein the strain gauge has a mesa structure and is enclosed by an insulation film.

30. The pressure sensing apparatus according to claim 28,

wherein a thermal expansion coefficient of the base substrate of the silicon-on-insulator substrate is between a thermal expansion coefficient of silicon and a thermal expansion coefficient of the stem.

31. The pressure sensing apparatus according to claim 26,

wherein each corner of the back surface of the sensor chip has an obtuse angle.

32. The pressure sensing apparatus according to claim 26,

wherein the sensor chip is a monocrystalline silicon substrate having a back surface provided with an insulation film.

33. A method of manufacturing a pressure sensing apparatus comprising:

(a) preparing a housing having a pressure passageway provided with a pressure inlet port for introducing pressure into the pressure passageway;

(b) placing a metallic stem, which has a diaphragm at a first side and an opening at a second side, in the pressure passageway in such a manner that the introduced pressure is applied to a back surface of the diaphragm through the opening;

(c) preparing a sensor chip, which include a sensing section and has a front surface provided with the sensing section;

(d) activating a front surface of the diaphragm and a back surface of the sensor chip;

(e) generating electrostatic attraction force between the front surface of the diaphragm and the back surface of the sensor chip; and

(f) bonding the activated back surface of the sensor chip directly to the activated front surface of the diaphragm by the electrostatic attraction force.

34. The method according to claim 33,

wherein in step (c) the sensor chip includes a processing circuit for processing an output of the sensing section.