High frequency power transistor having reduced interconnection inductance and thermal resistance

• US 4,161,740 A
• Filed: 11/07/1977
• Issued: 07/17/1979
• Est. Priority Date: 11/07/1977
• Status: Expired due to Term

• Current Assignee: SGS-Thomson Microelectronics (STMicroelectronics NV)
• Original Assignee: Microwave Semiconductor Corporation
• Inventors: Frey, Richard H.
• Primary Examiner(s): Wojciechowicz, Edward J.
• Application Number:
  US05/849,302
• Time in Patent Office: 617 Days
• Field of Search: 357/36, 357/40, 357/52, 357/54, 357/68, 357/55, 357/71
• US Class Current: 257/579
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/49175 Parallel arrangements
• CPC Class Codes: H01L 2224/81801 Soldering or alloying
• CPC Class Codes: H01L 23/4824 Pads with extended contours, e.g. grid structure, branch structure, finger structure
• CPC Class Codes: H01L 23/66 High-frequency adaptations
• CPC Class Codes: H01L 24/49 of a plurality of wire connectors
• CPC Class Codes: H01L 24/81 using a bump 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 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 Silicon [Si]
• CPC Class Codes: H01L 2924/01033 Arsenic [As]
• CPC Class Codes: H01L 2924/01072 Hafnium [Hf]
• CPC Class Codes: H01L 2924/01074 Tungsten [W]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/30105 : Capacitance
• CPC Class Codes: H01L 2924/30107 : Inductance
• CPC Class Codes: H01L 2924/3011 : Impedance
• CPC Class Codes: H01L 2924/30111 : matching

Abstract

A transistor having small, closely spaced emitter and base contact areas and an active area capable of generating heat to be removed, is provided with an electrode structure comprising a finger electrode for connecting emitter or base contact areas with one or more bonding pads beside the active area and, electrically insulated from the finger electrode, a bonding plate electrode overlaying at least a portion of the active area for electrically contacting the base or emitter contact areas, respectively. This contact structure has reduced interconnection inductance and resistance, reduced MOS capacitance, and reduced thermal resistance. In addition, it provides a structure which is suitable for both conventional and flip chip mounting.

Claims

1. In a microwave power transistor of the type comprising a base pocket active area capable of generating heat to be removed, a plurality of spaced emitter rows within the boundaries of said base pocket and a plurality of discrete base areas closely spaced between successive spaced emitter rows, an improved electrical contact structure comprising:

bonding pad means on two sides of said base pocket active area;

a finger electrode structure for making electrical contact with said discrete base areas, said fingers extending across said base pocket active area for making electrical contact with said bonding pad means;

an insulating layer overlying said finger electrode structure in the region overlying said base pocket active area; and

emitter bonding plate means for making electrical contact with said emitter rows, said emitter bonding plate means overlying at least a portion of said base pocket active area and being insulated from said finger electrode structure by said insulating layer.

2. A transistor according to claim 1 wherein each of said emitter rows comprises a plurality of emitter sites connected together by a contact strip of conductive material.

3. A transistor according to claim 1 wherein said emitter bonding plate means overlies substantially all of said active area.

4. A high frequency power transistor comprising:

a collector layer of a first type of semiconductor material;

a base pocket layer of opposite type of semiconductor material overlaying said collector layer and defining therewith a base-collector junction;

a plurality of rows of spaced emitter areas of said first type of semiconductor material extending into said base pocket layer to form base-emitter junctions around the peripheries of said emitter areas;

a first insulating layer overlying said base layer;

a plurality of openings extending through said first insulating layer to said emitter areas;

a plurality of openings extending through said first insulating layer to a plurality of discrete portions of said base pocket layer;

conductive base contact means connecting said plurality of discrete portions of said base pocket layer to enlarged contact regions on one or more sides of said base pocket;

a second insulating layer overlying said conductive base contact means in the region overlying said base pocket layer; and

conductive emitter contact means overlying and contacting said emitter areas and overlying said second insulating layer in regions overlying said conductive base contact means, said conductive emitter contact means being insulated from said conductive base contact means by said second insulating layer.