Bipolar junction transistor incorporating integral field plate

• US 6,445,058 B1
• Filed: 05/17/2000
• Issued: 09/03/2002
• Est. Priority Date: 12/03/1999
• Status: Expired due to Fees

• Current Assignee: Microsemi Semiconductor (U.S.) Inc. (Microchip Technology Incorporated)
• Original Assignee: Legerity Incorporated (Microsemi Semiconductor Corp.)
• Inventors: Moore, William E., Thiel, Frank L., Shiota, Philip S.
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Nhu, David
• Application Number:
  US09/573,149
• Time in Patent Office: 839 Days
• Field of Search: 257/197, 257/256, 257/302, 257/341, 257/474, 257/556, 257/557, 257/565, 257/351, 257/575, 257/585
• US Class Current: 257/565
• CPC Class Codes: H01L 29/0804 Emitter regions of bipolar transistors
• CPC Class Codes: H01L 29/402 Field plates
• CPC Class Codes: H01L 29/7322 having emitter-base and base-collector junctions leaving at the same surface of the body, e.g. planar transistor

Abstract

A semiconductor process is disclosed which forms a field plate structure that integrally contacts an emitter region of a bipolar junction transistor by construction, without intervening interconnect layers or contacts. In one embodiment, a single-layer polysilicon electrode forms a field plate electrode which integrally interconnects to a traditional diffused emitter region formed before the polysilicon layer is deposited. This allows for deeper emitter regions required by the deep base regions needed for high-voltage bipolar devices. Moreover, the polysilicon layer, including the polysilicon electrode forming the field plate electrode, may be used as a local interconnect layer.

Claims

1. A bipolar junction transistor structure comprising:

a collector region, a base region, and an emitter region formed within a semiconductor body, said collector and base regions defining therebetween a collector/base junction intersecting a top surface of the semiconductor body;

a single-layer conductive electrode which contacts the emitter region and which is vertically aligned with and which lies directly above the collector/base junction at its intersection with the top surface, said conductive electrode extending at least a predetermined distance in a direction toward and disposed over the collector region and also extending at least a predetermined distance in a direction toward and disposed over the base region, thereby forming an integral field plate structure and emitter region contact; and

an interconnect element contacted to the conductive electrode to provide an electrical connection to the emitter region and to the field plate structure.

2. A structure as in claim 1 the conductive electrode includes an opening over the base region to accommodate a contact to the base region independent of the contact to the emitter region.

3. A structure as in claim 1 wherein the contact to the conductive electrode is disposed above the emitter region.

4. A structure as in claim 1 wherein the contact to the conductive electrode is disposed overlying a dielectric layer above the base region.

5. A structure as in claim 1, wherein the contact to the conductive electrode is disposed overlying a dielectric layer above the collector region outside of the base region.

6. A structure as in claim 1 wherein the bipolar junction transistor structure comprises a vertical junction transistor structure.

7. A structure as in claim 1 wherein the bipolar junction transistor structure comprises a lateral junction transistor structure.

8. A structure as in claim wherein:

the single-layer conductive electrode comprises a polysilicon electrode.

9. A bipolar junction transistor structure comprising:

a collector region formed within a semiconductor body having, where the collector region reaches a top surface of the semiconductor body, a first dielectric layer thereabove;

a base region formed within the collector region having, where the base region reaches the top surface of the semiconductor body, a second dielectric layer thereabove, said collector and base regions defining therebetween a collector/base junction intersecting the top surface of the semiconductor body;

an emitter region formed within the base region;

a polysilicon electrode disposed above and contacting the emitter region, and further disposed directly above and vertically aligned with the intersection of the collector/base junction with the top surface of the semiconductor body, said conductive electrode extending at least a predetermined distance in a direction toward and disposed over the collector region and also extending at least a predetermined distance in a direction toward and disposed over the base region, whereby the conductive electrode forms an integral field plate structure and emitter region contact; and

an interconnect element contacted to the conductive electrode for providing an electrical connection to the emitter region and for biasing the field plate structure with the emitter region voltage.

10. A structure as in claim 9 wherein the polysilicon electrode includes an opening therethrough disposed over the base region to accommodate a contact to the base region independent of the contact to the emitter region.

11. A structure as in claim 9 wherein:

the predetermined distance toward the collector region falls within an approximate a range of 8-12 microns; and

the predetermined distance toward the base region falls within an approximate range of 3-4 microns.

12. A structure as in claim 9 wherein the contact to the polysilicon electrode is disposed above the emitter region.

13. A structure as in claim 9 wherein the contact to the polysilicon electrode is disposed overlying a dielectric layer above the base region.

14. A structure as in claim 9 wherein the contact to the polysilicon electrode is disposed overlying a dielectric layer above the collector region outside of the base region.

15. A structure as in claim 9 wherein the bipolar junction transistor structure comprises a vertical junction transistor structure.

16. A structure as in claim 9 wherein the bipolar junction transistor structure comprises a lateral junction transistor structure.