Lateral RF MOS device with improved breakdown voltage

• US 6,271,552 B1
• Filed: 10/04/1999
• Issued: 08/07/2001
• Est. Priority Date: 10/04/1999
• Status: Expired due to Term

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: Xemod, Inc. (Qorvo, Inc.)
• Inventors: D'Anna, Pablo Eugenio
• Primary Examiner(s): Tran, Minh Loan
• Assistant Examiner(s): DICKEY, THOMAS L
• Application Number:
  US09/413,912
• Time in Patent Office: 673 Days
• Field of Search: 257/288, 257/491-94, 257/336, 257/344, 257/408
• US Class Current: 257/288
• CPC Class Codes: H01L 29/0847 of field-effect transistors with insulated gate H01L29/0653 takes precedence; with a passive supplementary region between source or drain and substrate related to punch-through, capacity or isolation phenomena H01L29/1079; with LDD or DDD structure H01L29/7833; for thin film transistors H01L29/78618
• 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 29/41766 with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/456 on silicon
• CPC Class Codes: H01L 29/7835 with asymmetrical source and drain regions, e.g. lateral high-voltage MISFETs with drain offset region, extended drain MISFETs

Abstract

The lateral RF MOS device having two drain drift regions and a conductive plug source connection structure is disclosed. The usage of two drain drift regions results in the increased source-drain breakdown voltage and in increased maximum drain current density. The lateral RF MOS device of the present intention can be used for high power and high frequency applications.

Claims

1. A lateral RF MOS transistor comprising:

a semiconductor material of a first conductivity type, said semiconductor material having a first dopant concentration and a top surface;

a conductive gate overlying and insulated from said top surface of said semiconductor material;

a first region formed completely within said semiconductor material of said first conductivity type, said first region being of a second conductivity type and having a second dopant concentration to form a first enhanced drain drift region of said RF MOS transistor structure;

a second region formed in said semiconductor material, said second region being of said second conductivity type and having a third dopant concentration to form a second enhanced drain drift region of said RF MOS transistor, said second region contacting said first region, said third dopant concentration being less than said second dopant concentration;

a third region formed in said semiconductor material, said third region being of said second conductivity type and having a fourth dopant concentration greater than said second dopant concentration to form a drain region of said RF MOS transistor, said third region contacting said second region;

a fourth region formed in said semiconductor material, said fourth region being of said first conductivity type and having a fifth dopant concentration to form a body region of said RF MOS transistor structure, said fifth dopant concentration being equal or greater than said first dopant concentration, said fourth region having a first end underlying said conductive gate, any remaining portion of said semiconductor material underlying said gate being of said first conductivity type;

a fifth region formed in said semiconductor material, said fifth region being of said second conductivity type and having a sixth dopant concentration to form a source region of said RF MOS transistor structure, said fifth region being located within said fourth region;

a sixth region formed in said semiconductor material, said sixth region being of said first conductivity type and having a seventh dopant concentration to form a contact enhancement region of said RF MOS transistor structure, said seventh dopant concentration being greater than said fifth dopant concentration of said fourth region, said sixth region being located within said fourth region; and

a conductive plug region formed in said contact enhancement region and said body region of said semiconductor material.

2. The lateral RF MOS transistor structure of claim 1, wherein said conductive plug region connects said source region and said body region of said semiconductor material to a backside of said structure.

3. The lateral RF MOS transistor structure of claim 1, wherein said conductive plug region connects a top or lateral surface of said source and a lateral surface of said body region of said semiconductor material to a highly conductive substrate of said structure.

4. The lateral RF MOS transistor structure of claim 1, wherein said first conductivity type is a P type.

5. The lateral RF MOS transistor structure of claim 1, wherein said conductive plug comprises a metal plug.

6. The lateral RF MOS transistor structure of claim 1, wherein said conductive plug comprises a silicided plug.

7. The lateral RF MOS transistor structure of claim 6, wherein said silicided plug comprises a tungsten silicided plug.

8. The lateral RF MOS transistor structure of claim 6, wherein said silicided plug comprises a titanium silicided plug.

9. The lateral RF MOS transistor structure of claim 6, wherein said silicided plug comprises a cobalt silicided plug.

10. The lateral RF MOS transistor structure of claim 6, wherein said silicided plug comprises a platinum silicided plug.