Through-substrate source contact for microwave FET

• US 3,986,196 A
• Filed: 06/30/1975
• Issued: 10/12/1976
• Est. Priority Date: 06/30/1975
• Status: Expired due to Term

• Current Assignee: Varian Associates
• Original Assignee: Varian Associates
• Inventors: Omori, Masahiro, Decker, David Richard
• Primary Examiner(s): Wojciechowicz, Edward J.
• Application Number:
  US05/591,690
• Time in Patent Office: 470 Days
• Field of Search: 357/22, 357/23, 357/68, 357/81, 357/55
• US Class Current: 257/276
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 2224/48599 Principal constituent of the connecting portion of the wire connector being Gold (Au)
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/78 Apparatus for connecting with wire connectors
• CPC Class Codes: H01L 2224/85201 Compression bonding
• CPC Class Codes: H01L 2224/85203 Thermocompression bonding
• CPC Class Codes: H01L 2224/85205 Ultrasonic bonding
• CPC Class Codes: H01L 2224/85399 Material
• CPC Class Codes: H01L 23/36 Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks H01L23/28, H01L23/40, H01L23/42, H01L23/44, H01L23/46 take precedence; heating H01L23/345
• CPC Class Codes: H01L 23/481 Internal lead connections, e.g. via connections, feedthrough structures
• CPC Class Codes: H01L 23/66 High-frequency adaptations
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 24/85 : using a wire connector wire bonding in general B23K20/004
• CPC Class Codes: H01L 29/4175 : for lateral devices where the connection to the source or drain region is done through at least one part of the semiconductor substrate thickness, e.g. with connecting sink or with via-hole
• 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 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01027 : Cobalt [Co]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01031 : Gallium [Ga]
• CPC Class Codes: H01L 2924/01032 : Germanium [Ge]
• CPC Class Codes: H01L 2924/01041 : Niobium [Nb]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• 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 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/10158 : at the passive surface
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/12032 : Schottky diode
• CPC Class Codes: H01L 2924/1306 : Field-effect transistor [FET]
• CPC Class Codes: H01L 2924/13063 : Metal-Semiconductor Field-Effect Transistor [MESFET]
• CPC Class Codes: H01L 2924/15153 : the die mounting substrate comprising a recess for hosting the device
• CPC Class Codes: H01L 2924/1517 : Multilayer substrate
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19043 : being a resistor
• CPC Class Codes: H01L 2924/20752 : larger or equal to 20 microns less than 30 microns
• CPC Class Codes: H01L 2924/30107 : Inductance
• CPC Class Codes: H01L 2924/3011 : Impedance

Abstract

A microwave field effect transistor (FET) comprises source, gate, and drain electrodes deposited on an epitaxial layer grown on a semi-insulating substrate. The FET has lowered thermal resistance, lowered source lead inductance, and lowered gate series resistance, together with concomitant performance improvements, through the use of a novel source electrode connection which comprises a deposited or plated through metallic contact extending from the bottom of the wafer, through a hole in the substrate and epitaxial layer, to the underside of the source or other electrode which is deposited on the top side of the epitaxial layer. The chip, comprising the substrate, epitaxial layer, and top electrodes, is mounted on a heat sink. The chip'"'"'s underside, including the bottom surface of the plated through source contact, is conductively bonded to the top surface of the heat sink.

Claims

1. A field effect transistor comprising a body of semiconductive material having upper and lower surfaces, at least three spaced metallic electrodes on the upper surface of said body, a first of which is positioned between the second and third of said electrodes in the plane of said surface, said first electrode making a rectifying contact to said surface, said second and third electrodes each making an ohmic contact to said surface, and means providing a contact to one of said ohmic contact electrodes from the lower surface of said body, said means comprising a metallic contact extending through said body from said lower surface thereof to the underside of said ohmic contact electrode, the sides of said metallic contact adjacent said body being in direct electrical contact with said body.

2. The transistor of claim 1 wherein said first, second and third electrodes are source, gate, and drain electrodes, said one of said ohmic contact electrodes being said source electrode.

3. The transistor of claim 1 wherein the surface of said metallic contact in contact with the underside of said ohmic contact electrode is in contact with a major portion of said underside.

4. The transistor of claim 3 wherein said surface of said metallic contact in contact with the underside of said ohmic contact is symmetrically positioned with respect to said underside.

5. The transistor of claim 1 wherein said metallic contact is gold and said body is composed essentially of III-V materials.

6. The transistor of claim 1 wherein said body comprises a substrate of relatively high resistivity and an epitaxial layer of lower resistivity over said substrate, said metallic contact extending through both said substrate and said epitaxial layer.

7. The transistor of claim 1 wherein said metallic contact is rectangular in cross section, the upper surface thereof in contact with said one electrode having a smaller area than the lower surface thereof, said lower surface thereof being coplanar with the lower surface of said body.

8. The transistor of claim 1 wherein a portion of said metallic contact, at the lower surface of said body, is conductively bonded to a heat sink.

9. The transistor of claim 8 wherein contact means are provided to said plurality of electrodes at the top surface of said body, other than said one electrode.