Lateral RF MOS device having a combined source structure

• US 6,034,415 A
• Filed: 04/08/1999
• Issued: 03/07/2000
• Est. Priority Date: 02/07/1998
• Status: Expired due to Term

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: Xemod, Inc. (Qorvo, Inc.)
• Inventors: Johnson, Joseph Herbert, D'Anna, Pablo Eugenio
• Primary Examiner(s): Clark, Sheila V.
• Application Number:
  US09/289,370
• Time in Patent Office: 334 Days
• Field of Search: 257/621, 257/345, 257/382, 257/622, 257/623, 257/624, 257/625
• US Class Current: 257/621
• CPC Class Codes: H01L 21/743 Making of internal connections, substrate contacts
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate
• CPC Class Codes: H01L 23/4824 Pads with extended contours, e.g. grid structure, branch structure, finger structure
• CPC Class Codes: H01L 29/1045 the doping structure being parallel to the channel length, e.g. DMOS like
• 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 29/7835 with asymmetrical source and drain regions, e.g. lateral high-voltage MISFETs with drain offset region, extended drain MISFETs
• 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 lateral RF MOS device having a combined source connection structure is disclosed. The combined source connection structure utilizes a diffusion area and a conductive plug region. In one embodiment, the diffusion source area forms a contact region connecting the top surface of the semiconductor material to a highly conductive substrate of the lateral RF MOS transistor structure. In another embodiment, the diffusion source area is located completely within the epitaxial layer of the lateral RF MOS transistor structure. The conductive plug region makes a direct physical contact between a backside of the semiconductor material and the diffusion contact area.

Claims

1. A lateral RF MOS transistor structure having a combined source structure 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 an enhanced drain drift region of said lateral 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 greater than said second dopant concentration to form a drain region of said lateral RF MOS transistor structure, said second region contacting said first region;

a third region formed in said semiconductor material, said third region being of said first conductivity type and having a fourth dopant concentration to form a body region of said lateral RF MOS transistor structure, said fourth dopant concentration being equal or greater than said first dopant concentration, said third 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 fourth region formed in said semiconductor material, said fourth region being of said second conductivity type and having a fifth dopant concentration to form a source region of said lateral RF MOS transistor structure, said fourth region being located within said third region;

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

and

a conductive plug region formed in said semiconductor material;

wherein said conductive plug region makes a direct physical contact between a backside of said semiconductor material and said sixth region formed in said semiconductor material of said lateral RF MOS transistor structure.

2. The lateral RF MOS transistor structure of claim 1, wherein said sixth region further connects said top surface of said semiconductor material to said highly conductive substrate of said lateral RF MOS transistor structure.

3. The lateral RF MOS transistor structure of claim 1, wherein said sixth region is located within said semiconductor material of said first conductivity type.

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 copper silicided plug.

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