ELEMENT WAFER AND METHOD FOR MANUFACTURING THE SAME

• US 20090230485A1
• Filed: 07/14/2008
• Published: 09/17/2009
• Est. Priority Date: 03/17/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: OKUMURA, Mika, Yamaguchi, Yasuo, Horikawa, Makio, Satou, Kimitoshi
• Granted Patent: US 8,304,899 B2
• Time in Patent Office: Days
• US Class Current: 257/415
• 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. A method for manufacturing an element wafer, comprising the steps of:

preparing a semiconductor wafer;

stacking a plurality of films on the semiconductor wafer and concurrently processing each of the films to form an element in a central region of the plurality of films on the semiconductor wafer; and

forming a recessed portion and/or a plurality of openings in at least one of the plurality of films, the recessed portion and the openings being arranged outside the central region and surrounding the central region.

2. The method according to claim 1, wherein

the plurality of films include a sacrificial film, and

the step of forming the element includes an etching process using the sacrificial film.

3. The method according to claim 1, wherein

the element is an acceleration sensor having a thin film structure and wiring, 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 step of forming the element includes the sub-steps of:

stacking an insulating film on the semiconductor wafer;

forming the wiring on the insulating film;

stacking a conductive film on the insulating film on which the wiring is formed, the conductive film being provided to form the thin film structure; and

processing the conductive film to form the thin film structure; and

the recessed portion and/or the plurality of openings are formed before the conductive film is stacked.

4. The method according to claim 3, wherein

the step of forming the recessed portion and/or the plurality of openings includes a sub-step of removing a portion of the films stacked on the semiconductor wafer by etching during stacking the plurality of films, the portion of the films being present outside the central region,

the step of forming the element includes a sub-step of stacking an additional film on a remaining portion of the films, the remaining portion of the films not being removed by the etching and being present outside the central portion, and

the method further comprises the steps of:

preparing a cap plate having a cap member for capping the acceleration sensor; and

contacting the cap plate with the additional film stacked on the remaining portion of the films to fix the cap plate to the semiconductor wafer above which the acceleration sensor is formed.

5. The method according to claim 1, wherein

in the step of forming the element, a plurality of the elements are formed side by side above the semiconductor wafer, and

the method further comprises the step of forming recessed portions in at least one of the plurality of films to partition the elements from each other.

8. A method for manufacturing an element, comprising:

the method according to claim 1; and

a step of dicing the semiconductor wafer above which the element is formed.

6. A method for manufacturing an element wafer, comprising the steps of:

preparing a semiconductor wafer;

stacking a plurality of films on the semiconductor wafer and concurrently processing each of the films to form a plurality of elements side by side in a predetermined region of the films stacked on the semiconductor wafer; and

forming recessed portions in at least one of the films excluding the top film of the plurality of films to partition the elements from each other.

7. The method according to claim 6, wherein

each of the elements is an acceleration sensor having a thin film structure and wiring, 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 step of forming the elements includes the sub-steps of:

stacking an insulating film on the semiconductor wafer;

forming the wiring on the insulating film;

stacking a conductive film on the insulating film on which the wiring is formed, the conductive film being provided to form the thin film structure; and

processing the conductive film to form the thin film structure; and

in the step of forming the recessed portions, the recessed portions are formed in the insulating film on which the wiring is formed.

9. An element wafer comprising:

a semiconductor wafer;

a film stacked on the semiconductor wafer; and

an element provided on a central region of the film stacked on the semiconductor wafer;

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, and

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.

10. The element wafer according to claim 9, wherein

the 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

another 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.

11. The element wafer according to claim 9, wherein

the number of the elements is two or more, and

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.

12. The element wafer according to claim 11, wherein

the 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.

13. A capped element wafer comprising:

an element wafer according to claims 9; and

a cap plate having a cap member for capping the acceleration sensor;

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 the protrusion.

14. 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;

wherein

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

15. 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.