Package for sealing an integrated circuit die

• US 7,508,064 B2
• Filed: 06/28/2005
• Issued: 03/24/2009
• Est. Priority Date: 06/06/1995
• Status: Expired due to Fees

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Roberts, Carl M. Jr., Martin, John R.
• Primary Examiner(s): Pham; Hoai v
• Application Number:
  US11/169,276
• Publication Number:
  US 20050269678A1
• Time in Patent Office: 1,365 Days
• Field of Search: 257678-680, 257/689, 257/704, 257/710, 257/724
• US Class Current: 257/704
• CPC Class Codes: B81B 7/0051 between the package lid and the substrate
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• 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 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 23/10 characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
• CPC Class Codes: H01L 23/49503 characterised by the die pad
• CPC Class Codes: H01L 23/49513 having bonding material between chip and die pad
• CPC Class Codes: H01L 24/48 of an individual wire connector
• 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 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/07802 : not being an ohmic electrical conductor
• CPC Class Codes: H01L 2924/10157 : at the active surface
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/1461 : MEMS
• CPC Class Codes: H01L 2924/16235 : Connecting to a semiconductor or solid-state bodies, i.e. cap-to-chip
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding

Abstract

A die has a part that is sealed with a cap. The seal can be hermetic or non-hermetic. If hermetic, a layer of glass or metal is formed in the surface of the die, and the cap has a layer of glass or metal at a peripheral area so that, when heated, the layers form a hermetic seal. A non-hermetic seal can be formed by bonding a cap with a patterned adhesive. The cap, which can be silicon or can be a metal paddle, is electrically coupled to a fixed voltage to shield the part of the die.

Claims

1. A semiconductor assembly comprising:

a die having a substrate;

a mass suspended over the substrate with anchors, and movable along a first direction, the movable mass having one or more fingers extending along a second direction perpendicular to the first direction;

stationary plates, wherein movement of the movable fingers relative to the stationary plates causes a change in capacitance that is used to measure acceleration; and

a cap bonded to the die, the cap surrounding the mass, the die and the cap defining a space therebetween so that the cap does not contact the mass.

2. The assembly of claim 1, wherein the cap is hermetically bonded to the die.

3. The assembly of claim 1, wherein the cap includes silicon.

4. The assembly of claim 3, wherein the cap is bonded to the die with a glass seal.

5. The assembly of claim 1, wherein the cap includes a metal paddle.

6. The assembly of claim 1, wherein the cap is bonded to the die with a glass seal.

7. The assembly of claim 1, wherein the cap is bonded to the die with a metal seal.

8. The assembly of claim 1, wherein the die is an integrated circuit die that has an integrated circuit in addition to the movable member.

9. The assembly of claim 1, wherein the movable member moves laterally in a plane parallel to the substrate.

10. The assembly of claim 1, wherein the cap covers some, but not all, of the face of the die.

11. The assembly of claim 1, wherein the cap is bonded to the die with an adhesive, wherein the pattern of the adhesive is chamfered at the corners of the cap.

12. The assembly of claim 1, wherein the space is defined by a cavity in the cap, the cavity having a depth of 2-20 microns.

13. The assembly of claim 12, wherein the cavity has a depth of 10-20 microns.

14. The assembly of claim 1, wherein the space is defined by a cavity in the cap, the cavity having a depth of 125-250 microns.

15. A semiconductor assembly comprising:

a die having a substrate;

a mass supported over at least a portion of the substrate with anchors and generally lying in a first plane, the mass being movable along a first direction and having a sensing element;

a stationary structure that is not movable relative to the substrate, wherein movement of the sensing element relative to the stationary structure causes a change in an electrical characteristic that is sensed to detect motion in at least one direction;

a cap hermetically bonded to the die to create a vacuum environment, the cap surrounding the mass, the die and the cap defining a space therebetween so that the cap does not contact the mass; and

a plastic package encapsulating the die and the cap.

16. A semiconductor assembly comprising:

a die having a substrate, the substrate having a well;

a mass recessed in the well of the substrate, coupled to the substrate with anchors, generally lying in a first plane, and movable along a first direction relative to the substrate, the movable mass having one or more sensing elements;

a stationary structure, wherein movement of the sensing element relative to the stationary structure causes a change in an electrical characteristic that is detected to sense motion in at least one direction in the first plane; and

a cap bonded to the die, the cap surrounding the mass, the die and the cap defining a space therebetween so that the cap does not contact the mass.

17. A semiconductor assembly comprising:

a die having a substrate;

a mass suspended over the substrate with anchors and generally lying in a first plane, and movable along a first direction, the movable mass having one or more fingers extending along a second direction perpendicular to the first direction;

stationary plates, wherein movement of the movable fingers relative to the stationary plates causes a change in capacitance that is used to sense motion in at least one direction that is in the first plane; and

a cap bonded to the die, the cap surrounding the mass, the die and the cap defining a space therebetween so that the cap does not contact the mass.