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Bipolar Transistors Using P- Epi On P+ Substrate, Instead of P- Substrate

IP.com Disclosure Number: IPCOM000037932D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Chuang, CT: AUTHOR [+3]

Abstract

A new starting wafer for bipolar transistors is provided and comprises a p+ substrate upon which a p- epitaxial layer is grown, followed by an n+ sublayer and an n epitaxial layer. The use of the p+ substrate in the new wafer eliminates the need for a special channel stop which is required by the prior art. Also, transistors product using the new wafer arrangement of a psubstrate and a p+ epi layer are much less sensitive to alpha particles effects than the transistors of the prior art with a resulting decrease in soft errors.

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Bipolar Transistors Using P- Epi On P+ Substrate, Instead of P- Substrate

A new starting wafer for bipolar transistors is provided and comprises a p+ substrate upon which a p- epitaxial layer is grown, followed by an n+ sublayer and an n epitaxial layer. The use of the p+ substrate in the new wafer eliminates the need for a special channel stop which is required by the prior art. Also, transistors product using the new wafer arrangement of a psubstrate and a p+ epi layer are much less sensitive to alpha particles effects than the transistors of the prior art with a resulting decrease in soft errors.

The new starting wafer 10 for a bipolar transistor is seen in Fig. 1. A p+ substrate 20 is provided with a p- epi layer 30 grown thereon. An n+ sublayer 40 is formed atop the p- epi, and an n epi layer 50 is grown on the n+ sublayer. The starting wafer 10 is in contrast to conventional starting wafers which comprise a p- substrate, an n+ sublayer and an n epi layer.

There are many advantages to the new starting wafer 10. First, in advanced bipolar transistors using the conventional starting wafers, isolation trenches are formed by implanting pregions as channel stops in the p- substrate. With the starting wafer 10 of Fig. 1, no such implantation is required as the player 20 is already provided. Second, the new starting wafer 10 provides a p- epi layer 30 on a p+ substrate 20, and such an arrangement is widely used in advance CMOS circuitry. Third, the provision of a l...