Element wafer and method for manufacturing the same

• US 8,304,899 B2
• Filed: 07/14/2008
• Issued: 11/06/2012
• Est. Priority Date: 03/17/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Okumura, Mika, Horikawa, Makio, Satou, Kimitoshi, Yamaguchi, Yasuo
• Primary Examiner(s): Yang, Minchul
• Application Number:
  US12/172,603
• Publication Number:
  US 20090230485A1
• Time in Patent Office: 1,576 Days
• Field of Search: 257/415, 257/684, 257/692, 257/725, 257/E23.031, 257/E29.342
• US Class Current: 257/725
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81C 1/00182 Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A recessed portion is provided in first and second insulating films, the first insulating film being stacked on a semiconductor wafer, the second insulating film being stacked on the first insulating film. The first and second insulating films are processed to form wiring in a formation region of the semiconductor wafer in which an acceleration sensor is to be formed. After a sacrificial film is stacked on the wiring and processed, a conductive film is stacked on the wiring and processed to form a plurality of thin film structures in the formation region. The recessed portion surrounds the formation region.

Claims

1. An element wafer comprising:

a semiconductor wafer;

a film stacked on the semiconductor wafer; and

plural elements provided on a central region of the film stacked on the semiconductor wafer and laterally spaced from each other to be diced into separated elements;

wherein

a plurality of films including said film are stacked in the outer region of the semiconductor wafer, the outer region being located outside of the central region,

a recessed portion and/or a plurality of openings are provided in at least one of the films stacked in the outer region of the semiconductor wafer, the recessed portion and/or the plurality of openings being arranged outside the central region and surrounding the central region, and

no said elements are provided in the outer region of the semiconductor wafer extending from outside the central region to the peripheral edge of the wafer.

2. The element wafer according to claim 1, wherein

each plural element is an acceleration sensor having wiring, a thin film structure, and a protrusion, the thin film structure including a support portion and a floating portion, the support portion being connected with the wiring, the floating portion being supported by the support portion and movable, the protrusion surrounding the thin film structure, and

an other film is stacked on said film in the outer region of the semiconductor wafer, and the upper surface of the protrusion is substantially flush with the upper surface of the other film stacked on the film in the outer region of the semiconductor wafer.

3. The element wafer according to claim 1, wherein

other recessed portions are provided in the central region of the plurality of films stacked on the semiconductor wafer to partition the elements from each other.

4. The element wafer according to claim 3, wherein

the other recessed portions to partition the elements are provided in such a way as to cross each other in the central region in which the elements are formed.

5. A capped element wafer comprising:

an element wafer according to claim 1; and

a cap plate having a cap member for capping each of the elements;

wherein

the cap plate is fixed to the element wafer under the condition that the cap plate is in contact with the upper surface of the top film of the plurality of films provided in the outer region of the semiconductor wafer and with the upper surface of protrusions surrounding each element.

6. The element wafer according to claim 1, wherein the recessed portion and/or plurality of openings provided in at least one of the films stacked in the outer region has a thickness less than a thickness of the at least one film adjacent to the recessed portion and/or plurality of openings.

7. The element wafer according to claim 1, wherein each of the plural elements is an acceleration sensor or structure of an acceleration sensor.

8. An element wafer comprising:

a semiconductor wafer;

an insulating film stacked on the semiconductor wafer;

plural pieces of wiring provided on a central region of the insulating film stacked on the semiconductor wafer;

a sacrificial film stacked on the insulating film and the wiring and having a plurality of openings formed therein, the opening exposing the respective pieces of the wiring; and

a plurality of thin film structures provided on the sacrificial film and connected with the respective pieces of the wiring through the openings,

wherein

recessed portions are provided in the sacrificial film to partition the thin film structures from each other, and

the sacrificial film has a thickness at the recessed portion less than a thickness of the sacrificial film adjacent to the recessed portion.

9. An element wafer, comprising:

a semiconductor wafer;

an insulating film stacked on the semiconductor wafer;

plural pieces of wiring provided on a central region of the insulating film stacked on the semiconductor wafer; and

a plurality of thin film structures provided on and connected with the respective pieces of the wiring, each of the plurality of thin film structures including at least one portion movable relative to the semiconductor wafer, wherein

recessed portions are provided in the insulating film to partition the thin film structures from each other, and

the insulating film has a thickness at the recessed portion less than a thickness of the film adjacent to the recessed portion.