Physical quantity sensor and method for manufacturing the same

• US 20060048572A1
• Filed: 09/08/2005
• Published: 03/09/2006
• Est. Priority Date: 09/08/2004
• Status: Active Grant

• Current Assignee: DENSO Corporation, Nippon Soken, Inc. (DENSO Corporation)
• Original Assignee: DENSO Corporation, Nippon Soken, Inc. (DENSO Corporation)
• Inventors: Itakura, Toshikazu, Isogai, Toshiki, Hayashi, Michitaka, Ishihara, Masato
• Granted Patent: US 7,181,966 B2
• Time in Patent Office: Days
• US Class Current: 73/335.40
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: Y10T 29/49007 Indicating transducer

Abstract

A capacitance type humidity sensor includes: a detection substrate including a detection portion on a first side of the detection substrate; and a circuit board including a circuit portion. The detection portion detects humidity on the basis of capacitance change of the detection portion. The circuit portion processes the capacitance change as an electric signal. The detection substrate further includes a sensor pad on a second side of the detection substrate. The sensor pad is electrically connected to the detection portion through a conductor in a through hole of the detection substrate.

Claims

1. A capacitance type humidity sensor comprising:

a detection substrate including a detection portion disposed on a first side of the detection substrate; and

a circuit board including a circuit portion, wherein

the detection portion detects humidity on the basis of capacitance change of the detection portion,

the circuit portion processes the capacitance change of the detection portion as an electric signal,

the detection portion is connected to the circuit portion electrically,

the detection substrate further includes a sensor pad disposed on a second side of the detection substrate, which is opposite to the first side of the detection substrate,

the sensor pad works as a connection terminal for the circuit portion, and

the sensor pad is electrically connected to the detection portion through a conductor in a through hole of the detection substrate.

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

a sealing member, wherein

the circuit board further includes a first pad as a connection terminal for the sensor pad,

the first pad is disposed on a first side of the circuit board,

the first pad is electrically connected to the circuit portion,

the detection substrate and the circuit board are stacked in such a manner that the second side of the detection substrate contacts the first side of the circuit board,

the sensor pad is electrically connected to the first pad through a connection member, and

the sealing member has a ring shape and disposed between the first side of the circuit board and the second side of the detection substrate so that the sealing member seals the sensor pad and the first pad.

3. The sensor according to claim 2, wherein

the circuit portion is disposed on the first side of the circuit board so that the sealing member seals the circuit portion together with the first pad.

4. The sensor according to claim 2, wherein

the circuit portion is disposed on a second side of the circuit board, which is opposite to the first side of the circuit board, and

the circuit portion is covered with a protection film.

5. The sensor according to claim 2, wherein

the circuit board further includes a second pad disposed on a part of the first side of the circuit board, the part which does not overlap the detection substrate, and

the second pad is electrically connected to the circuit portion through a wiring.

6. The sensor according to claim 1, wherein

the detection portion includes a pair of comb-teeth electrodes and a humidity sensitive film,

the detection substrate is made of a semiconductor substrate,

the comb-teeth electrodes are interleaved each other so that the comb-teeth electrodes are separated by a predetermined distance, and

the humidity sensitive film covers the comb-teeth electrodes and a space between the comb-teeth electrodes.

7. The sensor according to claim 6, wherein

the humidity sensitive film is capable of changing relative permittivity of the humidity sensitive film in accordance with the humidity in atmosphere,

the circuit board has flexibility so that the circuit board is deformable in accordance with a curvature of a mounting portion,

the sensor is mounted on the mounting portion in such a manner that a second side of the circuit board contacts the mounting portion, and

the second side of the circuit board is opposite to a first side of the circuit board, the first side facing the detection substrate.

8. The sensor according to claim 7, wherein

the circuit portion processes the capacitance change between the comb-teeth electrodes as an electric signal.

9. The sensor according to claim 7, wherein

the comb-teeth electrodes are electrically connected to the circuit portion through the sensor pad on the detection substrate.

10. The sensor according to claim 7, wherein

the mounting portion is a windshield of an automotive vehicle.

11. A method for manufacturing a capacitance type humidity sensor, the method comprising the steps of:

preparing a detection substrate including a detection portion disposed on a first side of the detection substrate;

preparing a circuit board including a circuit portion; and

electrically connecting between the detection portion and the circuit portion, wherein

the detection portion is capable of changing capacitance of the detection portion in accordance with humidity in atmosphere,

the circuit portion processes capacitance change of the detection portion as an electric signal,

the step of preparing the detection substrate includes a step of forming a sensor pad on a second side of the detection substrate,

the second side of the detection substrate is opposite to the first side of the detection substrate,

the sensor pad works as a connection terminal for the circuit portion, and

the sensor pad is electrically connected to the detection portion through a conductor in a through hole of the detection substrate.

12. The method according to claim 11, wherein

the step of preparing the circuit board includes a step of forming a first pad on the circuit board as a connection terminal for the sensor pad,

the first pad is disposed on a first side of the circuit board,

the first pad is electrically connected to the circuit portion,

the step of electrically connecting includes steps of:

stacking the detection substrate and the circuit board in such a manner that the second side of the detection substrate contacts the first side of the circuit board;

electrically connecting between the sensor pad and the first pad through a connection member; and

sealing with a sealing member between the first side of the circuit board and the second side of the detection substrate so that the sealing member seals a connection portion between the sensor pad and the first pad, and

the sealing member has a ring shape.

13. The method according to claim 12, wherein

the step of preparing the circuit board further includes a step of forming the circuit portion on the first side of the circuit board, and

the step of electrically connecting further includes a step of sealing the circuit portion together with the first pad by the sealing member.

14. A method of screen-printing paste on a substrate through a pattern hole of a screen mask by applying the screen mask on the substrate, the method comprising the steps of:

preparing a standard pattern hole in the screen mask as a positioning standard between the screen mask and the substrate;

forming a positioning pattern on the substrate;

printing the paste on a dummy substrate by applying the screen mask on the dummy substrate so that a standard pattern is printed on the dummy substrate through the standard pattern hole;

detecting a position of the standard pattern on the dummy substrate;

positioning the substrate in such a manner that a position of the positioning pattern on the substrate coincides with the position of the standard pattern, which is detected in the step of detecting; and

printing the paste on the substrate by applying the screen mask on the substrate in a state where the substrate is positioned in the step of positioning, wherein

the positioning pattern has almost the same shape as the standard pattern, and

the positioning pattern on the substrate is formed in accordance with a positioning relationship between the standard pattern hole and the pattern hole.

15. The method according to claim 14, wherein

the positioning pattern includes a plurality of positioning pattern parts, which are separated each other by a predetermined distance.

16. The method according to claim 15, wherein

the positioning pattern parts on the substrate sandwich a region on the substrate, and

in the step of printing the paste, the paste is printed in the region of the substrate through the pattern hole.

17. The method according to claim 14, wherein

the substrate includes a pair of electrodes, which are interleaved each other,

the paste includes polymer material of a humidity sensitive film,

the pattern hole is formed in the screen mask in such a manner that the pattern hole corresponds to a humidity-sensitive-film-to-be-formed region on the substrate, and

the humidity-sensitive-film-to-be-formed region covers the electrodes and a space between the electrodes.

18. The method according to claim 17, wherein

the positioning pattern on the substrate is provided by a portion not to be covered with the humidity sensitive film.

19. The method according to claim 17, wherein

the standard pattern hole has a L-shape or a circular shape.

20. The method according to claim 17, wherein

the standard pattern hole has a dimension on a plane of the substrate, and

the dimension of the standard pattern hole is in arrange between 50 μ

m and 1000 μ

m.

21. The method according to claim 17, wherein

the humidity sensitive film is made of poly imide,

the standard pattern hole has a dimension on a plane of the substrate, and

the dimension of the standard pattern hole is in arrange between 100 μ

m and 1000 μ

m.

22. Sensor equipment for generating an output in accordance with a physical quantity as a detection object, the equipment comprising:

a decoder; and

a semiconductor substrate including a plurality of memory cells, each of which includes a transistor for switching and a capacitor, wherein

the transistor in each memory cell includes a source region, a drain region, and a gate electrode,

the source region and the drain region have a first conductive type,

the gate electrode is disposed on the semiconductor substrate through a gate insulation film in such a manner that the gate electrode is sandwiched between the source region and the drain region,

the capacitor in each memory cell includes a trench, a semiconductor region, a dielectric film, and a capacitance electrode,

the trench is disposed in the semiconductor substrate,

the semiconductor region having the first conductive type is disposed in the trench, and connected to the source region,

the dielectric film is capable of changing dielectric constant of the dielectric film in accordance with the physical quantity,

the dielectric film is embedded in the semiconductor region in the trench in such a manner that the dielectric film is disposed on a surface of the semiconductor region,

the capacitance electrode is disposed on a surface of the dielectric film through an insulation film in such a manner that the capacitance electrode faces the trench,

the trench in each memory cell has an opening area, which is different in each memory cell, and

the decoder detects a state of each memory cell whether the memory cell is in a written state or in a unwritten state, and outputs the output in accordance with the state of the memory.

23. The equipment according to claim 22, wherein

the trench in each memory cell has a width, which is different in each memory cell so that the opening area of the trench is different in each memory cell.

24. The equipment according to claim 23, wherein

the width of the trench in each memory cell is obtained by multiplying a predetermined width by two to the Nth power, and

N represents natural number.

25. The equipment according to claim 22, wherein

the dielectric film is a humidity sensitive film, dielectric constant of which is changeable in accordance with humidity in atmosphere.

26. Sensor equipment for generating an output in accordance with a physical quantity as a detection object, the equipment comprising:

a decoder; and

a semiconductor substrate including a plurality of memory cells, each of which includes a transistor for switching and a capacitor, wherein

the transistor includes a source region, a drain region, and a gate electrode,

the source region and the drain region have a first conductive type,

the gate electrode is disposed on the semiconductor substrate through a gate insulation film in such a manner that the gate electrode is sandwiched between the source region and the drain region,

the capacitor includes a pair of comb-teeth electrodes and a dielectric film,

the comb-teeth electrodes are disposed on the semiconductor substrate,

the dielectric film is capable of changing dielectric constant of the dielectric film in accordance with the physical quantity,

the dielectric film fills a space between the comb-teeth electrodes,

the comb-teeth electrodes are separated each other by a distance,

the distance of a pair of the comb-teeth electrodes in each memory cell is different in each memory cell, and

the decoder detects a state of each memory cell whether the memory cell is in a written state or in an unwritten state, and outputs the output in accordance with the state of the memory.

27. The equipment according to claim 26, wherein

the distance of a pair of the comb-teeth electrodes in each memory cell is obtained by multiplying a predetermined distance by two to the Nth power, and

N represents natural number.

28. The equipment according to claim 26, wherein

the dielectric film is a humidity sensitive film, dielectric constant of which is changeable in accordance with humidity in atmosphere.