Semiconductor mechanical sensor

• US 7,407,827 B2
• Filed: 08/23/2005
• Issued: 08/05/2008
• Est. Priority Date: 08/21/1992
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Fujii, Tetsuo, Imai, Masahito
• Primary Examiner(s): Geyer; Scott B.
• Assistant Examiner(s): Nikmanesh; Seahvosh J
• Application Number:
  US11/210,006
• Publication Number:
  US 20060019421A1
• Time in Patent Office: 1,078 Days
• Field of Search: 438/48, 438/50, 438/51, 438/52, 257/E21.613
• US Class Current: 438/52
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 7/0006 Interconnects
• CPC Class Codes: C07C 303/32 of salts of sulfonic acids
• CPC Class Codes: C07C 303/44 Separation; Purification
• CPC Class Codes: C07C 309/17 containing carboxyl groups bound to the carbon skeleton
• 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: G01C 19/5656 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0817 for pivoting movement of the mass, e.g. in-plane pendulum
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49004 including measuring or testing of device or component part

Abstract

A semiconductor mechanical sensor having a new structure in which a S/N ratio is improved. In the central portion of a silicon substrate 1, a recess portion 2 is formed which includes a beam structure. A weight is formed at the tip of the beam, and in the bottom surface of the weight in the bottom surface of the recess portion 2 facing the same, an electrode 5 is formed. An alternating current electric power is applied between the weight portion 4 and the electrode 5 so that static electricity is created and the weight is excited by the static electricity. In an axial direction which is perpendicular to the direction of the excitation of the weight, an electrode 6 is disposed to face one surface of the weight and a wall surface of the substrate which faces the same. A change in a capacitance between the facing electrodes is electrically detected, and therefore, a change in a physical force acting in the same direction is detected.

Claims

1. A method of manufacturing a mechanical force sensing semiconductor device being provided with:

a substrate;

a movable portion which is disposed on said substrate and movably formed with respect to the substrate; and

an upper structural member which is formed at least on said movable portion and spaced therefrom via a space, wherein the method comprising;

a first step of filling a filling material at least on the upper surface of said movable portion being defined on said substrate;

a second step of forming layers to obtain said upper structural member on said filling material;

a third step of forming a window portion in said upper structural member; and

a fourth step of removing said filling material by etching achieved through said window portion to obtain said space at least between said movable portion and said upper structural member.

2. A method as set forth in claim 1, wherein:

said first step further having a step of filling the peripheral region of said movable portion around its bottom and side as well with said filling material; and

said fourth step further having a step of removing said filling material being filled around said peripheral region of said movable portion to obtain said space around the movable portion as well.

3. A method as set forth in claim 2, wherein said further step to said first step, where said filling material is filled around said peripheral region of said movable portion, is performed prior to said first step of filling the upper surface of said movable portion with said filling material.

4. A method as set forth in claim 1, wherein said window portion is formed at each of a plurality of locations facing to the space to be disposed close to the side of said movable portion.

5. A method as set forth in claim 1, wherein said upper structural member comprising both an insulation film and an electrode layer;

and

said second step of forming layers to obtain said upper structural member further having (i) a step of forming said insulation film on said filling material and (ii) a step of forming a metal layer to obtain said electrode layer on the insulation film.

6. A method of manufacturing a mechanical force sensing semiconductor device being provided with:

a substrate;

a movable portion which is disposed on said substrate and movably formed with respect to the substrate; and

an upper structural member which is formed at least on said movable portion and spaced therefrom via a space, wherein the method comprising;

a first step of removing, by etching, a part of a semiconductor layer by which said movable portion is to be formed and defining the structure of the movable portion;

a second step of filling the region where said semiconductor layer is removed by said etching with a filling material and also filling the upper surface of said movable portion with a filling material;

a third step of forming layers to obtain said upper structural member on said filling material;

a fourth step of forming a window portion in said upper structural member; and

a fifth step of removing said filling material by etching achieved through said window portion to form said space around said movable portion so as to make the movable portion movable.

7. A method as set forth in claim 6, wherein

said second step further having a step of filling the peripheral region of said movable portion around its bottom and side as well with said filling material, which further step to said second step, where said filling material is filled around said peripheral region of said movable portion, is performed prior to said second step of filling the upper surface of said movable portion with said filling material.

8. A method as set forth in claim 6, wherein said window portion is formed at each of a plurality of locations facing to the space to be disposed close to the side of said movable portion.

9. A method as set forth in claim 6, wherein said upper structural member comprising both an insulation film and an electrode layer, and

said third step of forming layers to obtain said upper structural member further having (i) a step of forming said insulation film on said filling material and (ii) a step of forming a metal layer to obtain said electrode layer on the insulation film.