Method of hermetically encapsulating a semiconductor device by laser irradiation

• US 4,400,870 A
• Filed: 10/06/1980
• Issued: 08/30/1983
• Est. Priority Date: 10/06/1980
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Islam, Safidul
• Primary Examiner(s): Rutledge, L. Dewayne
• Assistant Examiner(s): Schiavelli, Alan E.
• Application Number:
  US06/194,108
• Time in Patent Office: 1,058 Days
• Field of Search: 29/588, 29/589, 174/52 FP, 174/52 H, 357/74, 219/121 L, 219/121 LC, 219/121 LD, 219/121 LM
• US Class Current: 29/832
• CPC Class Codes: H01L 21/50 Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/45099 Material
• 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 23/057 the leads being parallel to the base
• 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 2924/00014 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 2924/01029 Copper [Cu]
• 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 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/12042 LASER
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/15153 the die mounting substrate comprising a recess for hosting the device
• CPC Class Codes: H01L 2924/15165 Monolayer substrate
• CPC Class Codes: H01L 2924/16195 Flat cap [not enclosing an internal cavity]
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.

Abstract

A hermetic seal is formed without expensive precious metals by fusing two members of a semiconductor package together by scanning a laser beam along adjacent edges of the members. The compositions of the members which are fused together include ceramic, glass and metal. The method enables the formation of a hermetic seal at a relatively low temperature thereby greatly reducing the thermal stress on the semiconductor chip with resulting improvement in yields.

Claims

1. A method of hermetically sealing a semiconductor chip within a package comprising:

providing a first ceramic member having a plurality of conductive paths hermetically sealed therein;

providing a plurality of electrically conductive leads for making external connections to the conductive paths;

bonding a semiconductor chip to a surface of the first ceramic member;

forming electrical connections between regions of the semiconductor chip and the conductive paths;

providing a second ceramic member in abutting relationship with portions of the first ceramic member so as to define a compartment therebetween in which the semiconductor chip resides; and

exposing adjacent edges of the first and second ceramic members to a laser beam for a sufficient duration to fuse the adjacent edges together throughout a closed loop so as to hermetically seal the compartment from the surrounding atmosphere.

2. The method of claim 1 wherein the first and second ceramic members comprise similar compositions of aluminum oxide and glass.

3. The method of claim 2 wherein the first and second ceramic members each comprise from about 70% to about 80% aluminum oxide and from about 20% to about 30% glass.

4. The method of claim 1 wherein the ceramic members are maintained at a temperature of about 200°

C. during exposure to the laser beam.