Bipolar transistors with high voltage MOS transistors in a single substrate

• US 5,229,308 A
• Filed: 05/04/1992
• Issued: 07/20/1993
• Est. Priority Date: 04/30/1990
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Buhler, Steven A., Vo, Tuan A., Mojaradi, Mohamad M.
• Primary Examiner(s): QUACH, TUAN N
• Application Number:
  US07/878,141
• Time in Patent Office: 442 Days
• Field of Search: 437/31, 437/41, 437/44, 437/34, 437/56, 437/57, 357/23.4, 748/DIG. 9, 257/339
• US Class Current: 438/234
• CPC Class Codes: H01L 21/8249 Bipolar and MOS technology
• CPC Class Codes: Y10S 148/009 Bi-MOS

Abstract

A method of manufacturing a semiconductor device having a bipolar transistor for ordinary logic operation, as well as a high voltage MOS transistor which are provided in a single semiconductor substrate. The process includes the steps of making high voltage MOS transistors which comprises the steps of n-well fabrication, first drift region fabrication, second drift region fabrication, source and drain contact region fabrication and making bipolar transistors within the same silicon substrate as the high voltage MOS transistors which includes the step of base region fabrication where the steps for fabricating the second drift region of the high voltage MOS transistor and the base region of the bipolar transistor are combined so that both regions are created simultaneously.

Claims

1. A process for the simultaneous production of a bipolar transistor and a high voltage MOS transistor comprising the steps of:

(A) Providing a substrate having;

(i) at least on the high voltage MOS transistor portion a designated source region;

a designated gate region adjacent to said designated source region;

a designated drain region adjacent to said designated gate region; and

within said designated drain region a designated first drift region adjacent to said designated gate region, a designated drain contact region separated from said designated first drift region, and a designated second drift region interposed between said designated first drift region and said designated drain contact region;

(ii) at least on the bipolar transistor portion a designated base region;

a designated emitter contact region, and a designated collector contact region;

(B) forming a first drift region by implanting a given carrier to a given first concentration within said designated first drift region;

(C) forming a second drift region by implanting said given carrier to a given second concentration substantially higher than the first concentration and simultaneously forming a base region by implanting said given carrier in said designated base region of said bipolar transistor portion; and

(D) thereafter performing steps to complete the high voltage MOS transistor and the bipolar transistor.

2. The process in claim 1 wherein the steps to complete the high voltage MOS transistor and the bipolar transistor comprise:

(A) forming a source contact region and a drain contact region by implanting within said designated source region and said designated drain contact region said given carrier of a given third concentration substantially higher than said second concentration of the second drift region; and

(B) forming a collector contact region and an emitter contact region by implanting a second carrier within said designated collector contact region and said designated emitter contact region.

3. The process in claim 1 wherein the first drift region is formed prior to the simultaneous formation of said second drift region and said base region.

4. The process in claim 1 wherein the carrier first concentration is between approximately 1×

10¹⁷ and 5×

10¹⁷ carriers per cubic centimeters.

5. The process in claim 1 wherein the carrier second concentration is between approximately 4.5×

10¹⁷ and 11.5×

10¹⁷ carriers per cubic centimeter.

6. The process in claim 1 wherein said given carrier is boron.

7. The process in claim 1 wherein the second carrier is phosphorus.

8. The process in claim 1 wherein the step of:

(A) Providing a substrate having;

(i) at least on the high voltage MOS transistor portion a designated source region;

a designated gate region adjacent to said designated source region;

a designated drain region adjacent to said designated gate region; and

within said designated drain region a designated first drift region adjacent to said designated gate region, a designated drain contact region separated from said designated first drift region, and a designated second drift region interposed between said designated first drift region and said designated drain contact region;

(ii) at least on the bipolar transistor portion a designated base region, a designated emitter contact region, and a designated collector contact region;

is accomplished by;

(A) growing a thin oxide on the surface of said substrate;

(B) depositing a nitride layer on the surface of said thin oxide;

(C) patterning said nitride layer to designate;

(i) at least on the high voltage MOS transistor portion a designated source region, a designated gate region adjacent to said designated source region, a designated drain region adjacent to said designated gate region, and within said designated drain region a designated first drift region adjacent to said designated gate region, a designated drain contact region separated from said designated first drift region, and a designated second drift region interposed between said designated first drift region and said designated drain contact region,

(ii) at least on the bipolar transistor portion a designated base region, a designated emitter contact region, and a designated collector contact region.

9. The process in claim 8 wherein performing steps to complete the high voltage MOS transistor and the bipolar transistor are:

(A) forming a source contact region and a drain contact region by implanting, within said designated source region and said designated drain contact region, said given carrier to a given third concentration substantially higher than said second concentration; and

(B) forming a collector contact region and an emitter contact region by implanting a second carrier within said designated collector contact region and said designated emitter contact region.