Source connection structure for lateral RF MOS devices

• US 5,949,104 A
• Filed: 02/07/1998
• Issued: 09/07/1999
• 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: D'Anna, Pablo Eugenio, Johnson, Joseph Herbert
• Primary Examiner(s): GUAY, JOHN FRANCIS
• Application Number:
  US09/020,257
• Time in Patent Office: 577 Days
• Field of Search: 257/335, 257/382, 257/383, 257/384, 257/901, 257/276, 257/340, 257/343
• US Class Current: 257/335
• 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 source connection structure for a lateral RF MOS device is disclosed. The connection structure utilizes a conductive plug to connect a source area and a body area of the device with a backside. The usage of a conductive plug eliminates at least one doping area used for connectivity purposes. Therefore, the density of RF MOS devices per unit area of the chip is increased.

Claims

1. A lateral RF MOS transistor structure having a plug connective 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 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 RF MOS transistor, 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 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 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 contact enhancement region of said 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;

and

a conductive plug region formed in said source region and said body region of said semiconductor material;

wherein said conductive plug region connects said source region and said body region of said semiconductor material to a backside of said RF MOS transistor structure; and

wherein said conductive plug makes direct physical contact with said backside of the structure.

2. 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.

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

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

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

6. The lateral RF MOS transistor structure of claim 5, wherein said silicided plug comprises a tungsten silicided plug.

7. The lateral RF MOS transistor structure of claim 5, wherein said silicided plug comprises a titanium silicided plug.

8. The lateral RF MOS transistor structure of claim 5, wherein said silicided plug comprises a cobalt silicided plug.

9. The lateral RF MOS transistor structure of claim 5, wherein said silicided plug comprises a platinum silicided plug.