Semiconductor physical quantity sensor and production method thereof

• US 6,240,782 B1
• Filed: 02/11/1999
• Issued: 06/05/2001
• Est. Priority Date: 02/12/1998
• Status: Expired due to Term

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kato, Nobuyuki, Sakai, Minekazu, Fukada, Tsuyoshi, Yamamoto, Toshimasa
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US09/247,865
• Time in Patent Office: 845 Days
• Field of Search: 735/141.8, 735/143.2, 735/142.4, 735/143.8, 735/141.6, 735/142.1, 735/143.6, 257/415, 361/280, 361/283.1, 361/283.2, 361/283.3
• US Class Current: 73/514.32
• 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 semiconductor physical quantity sensor includes a substrate, a beam-structure movable portion and a fixed portion. The beam-structure movable portion is suspended by four anchors formed of polycrystalline films. A rectangular mass is suspended between beams. Movable electrodes project from both sides of the mass. First fixed electrodes and second fixed electrodes are fixedly provided on the surface of the substrate. The substrate has a laminated structure, wherein an oxide film, attaching film, insulating films, conductive film and insulating film are laminated on the substrate. An anchor formed from the conductive film is electrically connected to the attaching film. An electrode pad made of an aluminum film is provided the above the anchor. Because this structure enables the potential of the attaching film to be fixed, parasitic capacitance can be decreased.

Claims

1. A semiconductor physical quantity sensor comprising:

a substrate;

a sensor element portion formed on the substrate and having a movable portion, for detecting a capacitance change in response to a movement of the movable portion;

a surrounding portion provided at a surrounding region of the sensor element portion and insulated from the sensor element portion; and

potential fixing portion electrically connected to the surrounding portion for fixing a potential of the surrounding portion, the potential of the surrounding portion being fixed to a constant potential independent of a potential of the movable portion of the sensor element.

2. A semiconductor physical quantity sensor comprising:

a substrate unit having a first conductive film, an insulating film and a second conductive film, each of which is laminated on a semiconductor substrate;

a beam-structure having a movable electrode, supported on a surface of the substrate unit by a first anchor, the first anchor being formed from the second conductive film;

a fixed electrode facing the movable electrode, fixed to the surface of the substrate by a second anchor, the second anchor being formed from the second conductive film; and

film potential fixing portion electrically connected to the first conductive film for fixing a potential of the first conductive film, the potential of the first conductive film being fixed to a predetermined potential independent of a potential of a movable portion of the second conductive film.

3. The semiconductor physical quantity sensor according to claim 2, further comprising:

a first wire connected to the beam-structure and formed from the second conductive film; and

a second wire connected to the fixed electrode, formed from the second conductive film and crossing the first wire at an intersection of the first wire,

wherein one of the first and second wire has a bypass structure at the intersection by using the first conductive film.

4. The semiconductor physical quantity sensor according to claim 2, further comprising:

a surrounding portion fixed to the second conductive film at a surrounding region of the beam-structure and the fixed electrode; and

region potential fixing means for fixing a potential of the surrounding portion.

5. The semiconductor physical quantity sensor according to claim 4, further comprising:

capacitance change outputting means, including the movable electrode, for outputting the capacitance change between the movable electrode and the fixed electrode via the movable electrode,

wherein the region potential fixing means is connected to apply a potential to the surrounding portion which is equal to that of the movable electrode.

6. The semiconductor physical quantity sensor according to claim 2, further comprising:

capacitance change outputting means including the movable electrode, for outputting the capacitance change between the movable electrode and the fixed electrode via the movable electrode,

wherein the film potential fixing portion is connected to apply a potential to the first conductive film which is equal to that of the movable electrode.

7. A semiconductor physical quantity sensor comprising:

a substrate unit having a first conductive film, an insulating film and a second conductive film, each being laminated on a semiconductor substrate;

a beam-structure having a movable electrode, supported by a surface of the substrate unit by a first anchor, the first anchor being formed from the second conductive film;

a fixed electrode facing the movable electrode, fixed to the surface of the substrate by a second anchor, the second anchor being formed from the second conductive film and electrically separated from the first anchor; and

a potential outputting portion fixed to the surface of the substrate by a third anchor, the third anchor being formed from the second conductive film and electrically separated from the first anchor and the second anchor,

wherein the first conductive film is electrically connected to the potential outputting portion via the third anchor, a potential of the potential outputting portion is controlled to a predetermined potential independent of a potential of the movable electrode of the beam-structure.

8. A semiconductor physical quantity sensor comprising:

a substrate having a support substrate and an element forming film formed on the support substrate;

a sensor element portion formed on the substrate, having a movable portion, for detecting a capacitance change in response to a movement of the movable portion;

a surrounding portion provided at a surrounding region of the sensor element portion, divided from the sensor element portion by a trench formed in the element forming film; and

region potential fixing portion electrically connected to the surrounding portion for fixing a potential of the surrounding portion, the potential of the surrounding portion being fixed to a constant potential independent of a potential of the sensor element portion.

9. The semiconductor physical quantity sensor according to claim 8, wherein:

the sensor element portion includes a plurality of capacitance detecting portions, and

the region potential fixing portion is provided with respect to each of the capacitance detecting portions.

10. The semiconductor physical quantity sensor according to claim 9, wherein:

the sensor includes a first and a second capacitance detecting portions for detecting capacitance change of substantially the same level each other,

a distance between the first capacitance detecting portion and one portion of the region potential fixing portion is substantially the same as that between the second capacitance detecting portion and another portion of the region potential fixing portion.

11. The semiconductor physical quantity sensor according to claim 10, wherein the one portion of the region potential fixing portion and the another portion of the region potential fixing portion are arranged symmetrically with respect to a symmetrical line which perpendicularly intersects a line connecting the first and second capacitance detecting portions.

12. The semiconductor physical quantity sensor according to claim 9, wherein the sensor element portion comprises:

pads provided with respect to each capacitance detecting portion to lead a capacitance change;

conductive portions electrically connected to each pad and each capacitance detecting portion, respectively;

wherein resistance of each of the conductive portions is substantially the same, and volume of the trench surrounding each of the conductive portions are substantially the same.

13. The semiconductor physical quantity sensor according to claim 8, wherein:

the sensor includes first and second capacitance detecting portions for detecting capacitance change of substantially the same level each other,

the region potential fixing portion being arranged on a symmetrical line which perpendicularly intersects a line connecting the first capacitance detecting portion and second capacitance detecting portion.

14. The semiconductor physical quantity sensor according to claim 9, wherein each of the capacitance detecting portions comprises

a movable electrode provided to the movable portion;

a fixed electrode supported by the support substrate to face the movable electrode;

a capacitance change outputting means connected to the movable electrode for outputting the capacitance change between the movable electrode and the fixed electrode via the movable electrode, wherein the region potential fixing portion applies a potential equal to that of the movable electrode.

15. The semiconductor physical quantity sensor according to claim 8, wherein an insulating trench is formed at a region where an outer side of the region potential fixing portion located at the surrounding portion to insulate between an outer side of the insulating trench and an inner side of the insulating trench.

16. The semiconductor physical quantity sensor according to claim 8, wherein:

the sensor element portion includes;

a beam portion; and

a fixed portion that detects a capacitance change with the movable portion, and is divided from the surrounding portion by the trench,

wherein a part of the surrounding portion is extended to a portion between the beam portion and the fixed portion.