Physical quantity sensor and method for manufacturing the same

• US 20090261430A1
• Filed: 04/21/2009
• Published: 10/22/2009
• Est. Priority Date: 04/22/2008
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Suzuki, Shigenori, Sugiura, Kazuhiko, Fujii, Tetsuo, Yokoyama, Kenichi, Yokura, Hisanori
• Granted Patent: US 7,821,085 B2
• Time in Patent Office: Days
• US Class Current: 257/417
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type

Abstract

A physical quantity sensor includes: a sensor substrate including a first support substrate, a first insulation film and a first semiconductor layer, which are stacked in this order; a cap substrate including a second support substrate disposed on the first semiconductor layer, and has a P conductive type; and multiple electrodes, which are separated from each other. The first support substrate, the first insulation film and the first semiconductor layer have the P conductive type. The physical quantity is detected based on a capacitance between the plurality of electrodes, and the electrodes are disposed in the first semiconductor layer.

Claims

1. A physical quantity sensor comprising:

a sensor substrate including a first support substrate, a first insulation film and a first semiconductor layer, which are stacked in this order, wherein the first support substrate has a P conductive type impurity doped therein, the first insulation film has a P conductive type impurity doped therein, and the first semiconductor layer has a P conductive type impurity doped therein;

a cap substrate including a second support substrate, which is disposed on the first semiconductor layer, and has a P conductive type impurity doped therein; and

a plurality of electrodes, which are separated from each other,

wherein physical quantity is detected based on a capacitance between the plurality of electrodes, and

wherein the plurality of electrodes is disposed in the first semiconductor layer.

2. The physical quantity sensor according to claim 1,

wherein the second support substrate includes a through hole electrode, which penetrates the cap substrate.

3. The physical quantity sensor according to claim 2,

wherein the second support substrate is made of semiconductor, and

wherein the through hole electrode has a main structure, which is made from the second support substrate.

4. The physical quantity sensor according to claim 2,

wherein the through hole electrode is separated from other portions of the second support substrate with a groove so that an air isolation structure is provided.

5. The physical quantity sensor according to claim 4,

wherein the second support substrate is made of semiconductor,

wherein the cap substrate further includes a second insulation film,

wherein the second support substrate is covered with the second insulation film,

wherein the second support substrate includes a concavity, which is covered with the second insulation film, and

wherein the groove penetrates the second support substrate, and reaches the second insulation film disposed on the concavity.

6. The physical quantity sensor according to claim 4,

wherein the second support substrate is made of semiconductor,

wherein the cap substrate further includes a second insulation film and a second layer,

wherein the second support substrate is covered with the second insulation film,

wherein the second layer is made of material, which is different from the second insulation film,

wherein the second support substrate includes a concavity, which is covered with the second insulation film,

wherein the second layer covers the second insulation film, and

wherein the groove penetrates the second support substrate, and reaches the second insulation film disposed on the concavity so that an air isolation structure is provided.

7. The physical quantity sensor according to claim 5,

wherein the second insulation film includes a vertical extending portion, which is perpendicular to the cap substrate,

wherein the vertical extending portion is disposed on a sidewall of the concavity, and

wherein the groove reaches the vertical extending portion.

8. The physical quantity sensor according to claim 1,

wherein the cap substrate includes an electrolytic plating portion, which is disposed between the first semiconductor layer and the second support substrate.

9. The physical quantity sensor according to claim 1,

wherein the sensor substrate further includes a first film, which is disposed between the first semiconductor layer and the second support substrate,

wherein the first semiconductor layer is made of a material, which is the same as a material of the second support substrate, and

wherein the first film is made of a material, which is the same as a material of the second support substrate.

10. The physical quantity sensor according to claim 1,

wherein the cap substrate further includes a metal electrode, which is disposed on the second support substrate.

11. A physical quantity sensor comprising:

a support substrate;

an insulation film disposed on the support substrate;

a first electrode, which is movable, and disposed over the support substrate; and

a second electrode disposed on the insulation film,

wherein the insulation film has a P conductive type impurity doped therein,

wherein the insulation film includes a sidewall, which is curved downwardly,

wherein the insulation film has a width along with a direction parallel to the support substrate,

wherein the width of the insulation film becomes narrower as it goes from the support substrate to the second electrode,

wherein the first electrode is made of P conductive type silicon,

wherein the first electrode and the second electrode are separated from each other, and

wherein the physical quantity is detected based on a capacitance between the first electrode and the second electrode.

12. The physical quantity sensor according to claim 11,

wherein each of the first electrode and the second electrode has a resistivity in a range between 0.1 Ω

·

cm and 0.01 Ω

·

cm.

13. A method for manufacturing a physical quantity sensor comprising:

forming a sensor substrate including a first support substrate, a first insulation, film and a first semiconductor layer, which are stacked in this order, wherein the first support substrate has a P conductive type impurity doped therein, the first insulation film has a P conductive type impurity doped therein, and the first semiconductor layer has a P conductive type impurity doped therein;

forming a cap substrate including a second support substrate, which is disposed on the first semiconductor layer, and has a P conductive type impurity doped therein; and

forming a plurality of electrodes in the first semiconductor layer,

wherein the plurality of electrodes are separated from each other, and

wherein a physical quantity is detected based on a capacitance between the plurality of electrodes.

14. The method according to claim 13, further comprising:

forming a through hole electrode in the second support substrate to penetrate the cap substrate.

15. The method according to claim 14,

wherein the second support substrate is made of semiconductor, and

wherein the through hole electrode has a main structure, which is formed from the second support substrate.

16. The method according to claim 15, further comprising:

forming a groove in the second support substrate to separate the through hole electrode from other portions of the second support substrate so that an air isolation structure is formed.

17. The method according to claim 15, further comprising:

forming a concavity in the second support substrate;

forming a second insulation film on the second support substrate to cover the concavity with the second insulation film;

forming a groove in the second support substrate to separate the through hole electrode from other portions of the second support substrate so that an air isolation structure is formed,

wherein the groove penetrates the second support substrate, and reaches the second insulation film disposed on the concavity, and

wherein the second support substrate is made of semiconductor,

18. The method according to claim 15, further comprising:

forming a concavity in the second support substrate;

forming a second insulation film on the second support substrate to cover the concavity with the second insulation film;

forming a second layer on the second insulation film to cover the second insulation film with the second layer; and

forming a groove in the second support substrate to separate the through hole electrode from other portions of the second support substrate so that an air isolation structure is formed,

wherein the second support substrate is made of semiconductor,

wherein the second layer is made of material, which is different from the second insulation film, and

wherein the groove penetrates the second support substrate, and reaches the second insulation film disposed on the concavity.

19. The method according to claim 15, further comprising:

forming a concavity in the second support substrate;

forming a second insulation film on the second support substrate to cover the concavity with the second insulation film; and

forming a groove in the second support substrate to separate the through hole electrode from other portions of the second support substrate so that an air isolation structure is formed,

wherein the second insulation film includes a vertical extending portion, which is perpendicular to the cap substrate,

wherein the vertical extending portion is disposed on a sidewall of the concavity, and

wherein the groove reaches the vertical extending portion.

20. The method according to claim 13, further comprising:

forming an electrolytic plating portion in the cap substrate,

wherein the electrolytic plating portion is disposed between the first semiconductor layer and the second support substrate.

21. The method according to claim 15, further comprising:

forming a concavity in the second support substrate;

forming a second insulation film on the second support substrate to cover the concavity with the second insulation film;

forming an opening in the second insulation film;

forming a film in the opening to contact the second support substrate; and

bonding the film in the opening and the first semiconductor layer,

wherein the second support substrate is made of a material, which is the same as a material of the first semiconductor layer, and

wherein the film is made of a material, which is the same as the material of the second support substrate,

22. The method according to claim 13, further comprising:

forming a metal electrode on the second support substrate.

23. A method for manufacturing a physical quantity sensor comprising:

forming an insulation film on a support substrate, wherein the insulation film has a P conductive type impurity doped therein;

forming a semiconductor layer on the insulation film so that a sensor substrate is formed;

dividing the semiconductor layer into a plurality of parts with a hole so that the insulation film is exposed from the semiconductor layer via the hole, wherein the plurality of parts include a first electrode having a first width and a second electrode having a second width, which is wider than the first width; and

isotropically etching the insulation film via the opening so that the insulation film under the first electrode is removed, and the insulation film under the second electrode is partially removed,

wherein the physical quantity is detected based on a capacitance between the first electrode and the second electrode,

wherein the insulation film under the second electrode includes a support portion for supporting the second electrode on the support substrate, and

wherein a part of the insulation film adjacent to the support portion is removed in the isotropically etching the insulation film.

24. The method according to claim 23, further comprising:

forming an aluminum film on the semiconductor layer; and

patterning the aluminum film to be an electrode pad by a wet etching method.

25. The method according to claim 24

wherein the semiconductor layer is made of P conductive type silicon having an impurity concentration, which is equal to or higher than a predetermined value.