Microwave power SOI-MOSFET with high conductivity metal gate

• US 5,681,761 A
• Filed: 12/28/1995
• Issued: 10/28/1997
• Est. Priority Date: 12/28/1995
• Status: Expired due to Term

• Current Assignee: Ampleon Netherlands B.V. (Ampleon Coöperatief UA)
• Original Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Inventors: Kim, Manjin J.
• Primary Examiner(s): Niebling, John
• Assistant Examiner(s): MULPURI, SAVITRI
• Application Number:
  US08/580,409
• Time in Patent Office: 670 Days
• Field of Search: 437/21, 437/27, 437/29, 437/44, 437/45, 437/40 AS, 437/41 AS, 437/62, 437/190, 437/192, 437/913, 437/933, 257/347, 257/349, 257/348, 257/350-354
• US Class Current: 438/151
• CPC Class Codes: H01L 29/66772 Monocristalline silicon transistors on insulating substrates, e.g. quartz substrates H01L29/66666 takes precedence; thin film FinFETs H01L29/66795
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A technique for making a microwave, high power SOI-MOFET device is set forth together with such a device. An important aspect of this structure is the presence of high conductivity metal gate fingers for the device.

Claims

1. A method of manufacturing a high power, microwave frequency SOI-MOSFET device comprising the steps of

(a) forming a SOI device with a silicon layer on a substrate insulated with an oxide,

(b) forming a retrograde doping profile of a first conductivity type in the silicon layer,

(c) forming a plurality of metal gate fingers on a gate oxide over the silicon layer, the metal gate fingers comprising molybdenum.

(d) forming a self-aligned source-shield of the first conductivity type in the silicon layer, the source-shield being disposed adjacent to at least one of the metal gate fingers,

(e) forming a source region within the source-shield, and

(f) forming a drain region in the silicon layer, and said drain region being adjacent to the one metal gate finger at a side opposite to the source region with the source and drain regions being of a second conductivity type.

2. A method according to claim 1, wherein said plurality of metal gate fingers are formed with a long gate width to a relatively short gate length.

3. A method according to claim 1, further comprising the step of converting the top part of the molybdenum to molybdenum nitride.

4. A method according to claim 1, wherein at least one of the steps of forming the source-shield, the source region and the drain region comprises ion-implantation and further comprising the step of converting the top part of the molybdenum to a molybdenum compound prior to the ion-implantation step.

5. A method according to claim 4, wherein the step of converting comprises converting molybdenum to molybdenum nitride.

6. A method according to claim 1, further comprising the step of providing molybdenum contacts to at least one of the source and drain regions.

7. A method according to claim 6, further comprising the step of forming a barrier layer between the at least one source and drain region and the molybdenum so as to enhance ohmic contact.

8. A method according to claim 7, wherein the step of forming a barrier layer comprises using one or more of Cr, Ti and TiW.

9. A method according to claim 1, further comprising the step of connecting one or more of the metal gate fingers to a gate stem.

10. A method according to claim 9, wherein the step of connecting the gate fingers to a gate stem comprises using a molybdenum gate stem.

11. A method according to claim 9, further comprising the step of connecting the gate stem to a gate bus.

12. A method according to claim 11, wherein the steps of connecting comprise using molybdenum for at least one of the gate stem and the gate bus.

13. A method according to claim 1, wherein the step of forming a source-shield comprises providing a self-aligned diffusion through the window between adjacent metal gate fingers.

14. A method according to claim 1, wherein one or more of the steps of forming the source-shield, source region and drain region comprise minimizing the overlap between the respective diffusions and the gate defined by the metal gate finger.

15. A method according to claim 1, further comprising the step of forming at least one of a source contact in the source region and a drain contact in the drain region.