Acceleration sensor formed on surface of semiconductor substrate

• US 20040163472A1
• Filed: 09/04/2003
• Published: 08/26/2004
• Est. Priority Date: 02/26/2003
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Nagahara, Teruaki
• Granted Patent: US 6,892,577 B2
• Time in Patent Office: Days
• US Class Current: 73/593
• CPC Class Codes: B81B 7/0051 between the package lid and the substrate
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: H01L 2224/05554 being square
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2224/49175 Parallel arrangements
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding

Abstract

In a movable space, a boundary (CN1) between a ceiling surface and a wall surface of a cap (CA) has a curved plane. When stress is exerted on the cap (CA), this stress is dispersed accordingly around the boundary (CN1) having a high probability of generation of a crack. Therefore, generation of a crack in the cap (CN) is unlikely.

Claims

1. An acceleration sensor, comprising:

a semiconductor substrate provided with an acceleration detecting section, said acceleration detecting section having a movable part for detecting an acceleration;

a cap provided on a surface of said semiconductor substrate, said cap including a ceiling and at least one wall for defining a movable space for said movable part and hermetically sealing said movable space; and

stress absorbing section for absorbing stress exerted on said cap.

2. The acceleration sensor according to claim 1, wherein said stress absorbing section is formed by at least one curved boundary between the ceiling and the at least one wall.

3. The acceleration sensor according to claim 1, wherein said cap includes a cap base held between at least one wall of said cap and said semiconductor substrate, and said stress absorbing section is formed by at least one groove provided on at least one side surface of said cap base.

4. The acceleration sensor according to claim 1, wherein said stress absorbing section is formed by a foam resin cover covering said semiconductor substrate and said cap, said foam resin cover being lower in elastic modulus than said cap.

5. The acceleration sensor according to claim 1, wherein said stress absorbing section is formed by a column between a part of the ceiling of said cap and the surface of said semiconductor substrate.

6. The acceleration sensor according to claim 5, wherein said movable part includes a hole through which said column penetrates without touching said movable part.