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Avoiding Pipes in I/2/L Circuits

IP.com Disclosure Number: IPCOM000087083D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Barson, F: AUTHOR

Abstract

Pipes in bipolar devices are attributed to localized enhanced diffusion at dislocations. In bipolar circuits, such as integrated injection logic (I/2/L) circuits, which are operated in the inverse mode, that is the "subcollector" is operated as the emitter and the normal "emitter" becomes the collector, the inverse Beta (h(fe)) must be as high as possible, but current gain in the downward or "normal" mode need not be. It is thus feasible to implant the "emitter" provides (inverse collectors) directly "in place", as opposed to the commonly-used shallow implantation followed by a thermal drive-in. This implantation in place largely or completely avoids diffusion pipes by minimizing subsequent heat cycles.

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Avoiding Pipes in I/2/L Circuits

Pipes in bipolar devices are attributed to localized enhanced diffusion at dislocations. In bipolar circuits, such as integrated injection logic (I/2/L) circuits, which are operated in the inverse mode, that is the "subcollector" is operated as the emitter and the normal "emitter" becomes the collector, the inverse Beta (h(fe)) must be as high as possible, but current gain in the downward or "normal" mode need not be. It is thus feasible to implant the "emitter" provides (inverse collectors) directly "in place", as opposed to the commonly-used shallow implantation followed by a thermal drive-in. This implantation in place largely or completely avoids diffusion pipes by minimizing subsequent heat cycles. If normal devices are to be made on the same wafer, the usual diffused or implanted diffused methods could be used prior to implanting the inverse emitters in place.

This method permits increased yields and higher levels of integration in I/2/L or other bipolar structures operated in the inverse mode.

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