Semiconductor acceleration sensor

• US 6,763,716 B2
• Filed: 10/15/2002
• Issued: 07/20/2004
• Est. Priority Date: 02/18/2002
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Otani, Hiroshi, Nagahara, Teruaki
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US10/270,045
• Publication Number:
  US 20030159513A1
• Time in Patent Office: 644 Days
• Field of Search: 734/93, 735/141.6, 735/143.5, 735/143.6, 735/141.7, 735/141.8, 735/142.1, 735/143.2, 257/724, 257/778, 257/780
• US Class Current: 73/493
• CPC Class Codes: B81B 7/0006 Interconnects
• 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: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: H01L 2224/05554 being square
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• 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 2924/00014 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 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding

Abstract

A sensor chip connected to a signal processing IC is provided on a die pad, a stationary electrode and a movable electrode are arranged on a semiconductor substrate of the sensor chip, the stationary electrode and movable electrode are covered with a protective cap, a shield electrode layer is embedded in a top face part of a semiconductor substrate, and these elements are sealed with a sealing resin, thus, a potential of the movable electrode is obtained from an output potential of a capacity/voltage conversion circuit of a signal processing IC, and at least one of the shield electrode layer and protective cap is electrically connected to the movable electrode to thereby make identical to each other in potential.

Claims

1. A semiconductor acceleration sensor comprising:

a sensor chip connected to a signal processing IC on a die pad, said sensor chip having a semiconductor substrate;

a stationary electrode and a movable electrode arranged on said semiconductor substrate of said sensor chip;

a protective cap covering said stationary electrode and said movable electrode;

a shield layer which is embedded in a top face part of said semiconductor substrate; and

a sealing resin configured to seal said stationary electrode and said movable electrode,

wherein at least one of said shield layer and said protective cap is electrically connected to said movable electrode, thereby being identical to each other in potential.

2. The semiconductor acceleration sensor as claimed in claim 1, wherein an output terminal of a capacity/voltage conversion circuit of said signal processing IC and a top face of said sensor chip are connected to each other via a bonding wire.

3. The semiconductor acceleration sensor as claimed in claim 1, wherein, in a bonding arrangement in which said protective cap is bonded on said semiconductor substrate, there is provided a laminate structure in which an insulation nitride film is formed on said shield layer, a semiconductor support layer is formed on said insulation nitride film, an insulation oxide film is formed on said semiconductor support layer, and a bonding semiconductor layer to be used for cap bonding is formed on the insulation oxide film.

4. The semiconductor acceleration sensor as claimed in claim 3, wherein a hole part is provided in said insulation nitride film, a portion at which impurities of a constituent material of said semiconductor support layer is dispersed is formed in a partial region of said bonding semiconductor layer, an electrically conductive path which is partially electrically conductive from said shield layer to said protective cap via the hole part formed in said insulation nitride film, said semiconductor support layer, and said impurity dispersion part is formed, and said shield layer and said protective cap are electrically connected to each other via said electrically conductive path.

5. The semiconductor acceleration sensor as claimed in claim 4, wherein said movable electrode and said shield layer are electrically connected to each other via said electrically conductive path formed on a part of said semiconductor support layer of said protective cap.

6. The semiconductor acceleration sensor as claimed in claim 1, wherein a potential of said movable electrode is obtained as an output potential of a capacity/voltage conversion circuit of said signal processing IC.

7. The semiconductor acceleration sensor as claimed in claim 1, wherein a metal film is formed on an outer face of said protective cap, said signal processing IC is provided with a terminal part having a same potential as said movable electrode, and said terminal part having said same potential and the metal film on the outer face of said protective cap are electrically connected to each other via a bonding wire.

8. The semiconductor acceleration sensor as claimed in claim 1, wherein a hole part is provided on a part of an insulation oxide film laminated on the semiconductor substrate top face part of said sensor chip, and a semiconductor material is filled to be doped in the hole part, whereby said shield layer and the semiconductor substrate of said sensor chip are electrically connected to each other.

9. The semiconductor acceleration sensor as claimed in claim 6, wherein the semiconductor substrate of said sensor chip is bonded on said die pad by an electrically conductive adhesive agent, said signal processing IC is connected onto said die pad by an insulation adhesive agent, an output terminal of the capacity/voltage conversion circuit of said signal processing IC and said die pad are connected to each other via a bonding wire, and the semiconductor substrate of said sensor chip and said movable electrode are identical to each other in potential.

10. The semiconductor acceleration sensor as claimed in claim 1, wherein said movable electrode is configured to move toward said stationary electrode along said shield layer.

11. The semiconductor acceleration sensor as claimed in claim 1, wherein said signal processing IC comprises:

a capacity/voltage conversion circuit electrically connected to said movable electrode and configured to detect a capacitance change between said stationary electrode and said movable electrode and to convert the detected capacitance into a voltage,

wherein an output of said capacity/voltage conversion circuit is electrically connected to said at least one of said shield layer and said protective cap.

12. The semiconductor acceleration sensor as claimed in claim 1, wherein said protective cap and said movable electrode are electrically connected to said signal processing IC, thereby being identical to each other in potential.

13. The semiconductor acceleration sensor as claimed in claim 1, wherein said movable electrode and said at least one of said shield layer and said protective cap are electrically connected to each other via said signal processing IC.