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EPI Base P Diffusion Pocket for Second Breakdown Free Switching Transistor

IP.com Disclosure Number: IPCOM000086483D
Original Publication Date: 1976-Sep-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Oleszek, GM: AUTHOR [+4]

Abstract

The introduction of an avalanche diode having a breakdown voltage less than the second breakdown voltage of the intrinsic transistor to eliminate exposure to transistor reverse bias second breakdown is described in "Second Breakdown Free Switch Transistor" published in the IBM Technical Disclosure Bulletin, Vol. 19, No. 4, September 1976, pages 1308-1309.

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EPI Base P Diffusion Pocket for Second Breakdown Free Switching Transistor

The introduction of an avalanche diode having a breakdown voltage less than the second breakdown voltage of the intrinsic transistor to eliminate exposure to transistor reverse bias second breakdown is described in "Second Breakdown Free Switch Transistor" published in the IBM Technical Disclosure Bulletin, Vol. 19, No. 4, September 1976, pages 1308-1309.

Fig. 1 shows the equivalent circuit. The procedure described in Fig. 2 provides a means for incorporating such a diode as an integrated structure of the device during normal transistor processing.

The starting wafer 10 (step 1) is first prepared, as in steps 2 and 3, by fabricating pockets 12 of P-type material on the front side of 10 in alignment with the intended base contact areas of the finished devices. This preparation utilizes oxidation, etching, and diffusion steps resulting in the configuration seen at step
3.

In step 4, the SiO(2) has been etched away and an epitaxial P-layer 14 has been deposited on the top surface. At step 5, thermal oxidation provides SiO(2) layers 16 and 18. At step 6, layer 16 has been etched away selectively, 18 has been etched away completely, an N diffusion has been applied at both surfaces of the wafer, and a SiO(2) layer 20 has been regrown thereover during the thermal diffusion process. The bottom N+ diffusion 24 will form the collector contact plane and the top N+ diffusions 26 will form the emitter...