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Harper PNP Cell Designed With U-Shaped PNP Injector for High Beta

IP.com Disclosure Number: IPCOM000062139D
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 87K

Publishing Venue

IBM

Related People

Akrout, C: AUTHOR [+4]

Abstract

This article describes the realization of an unsaturated Harper PNP cell in bipolar technology with polysilicon base and trench isolation. The well-known Harper cell (half) is depicted in Fig. 1, and the novel implementation is shown in Fig. 2. The collector of the lateral PNP transistor is designed to have a maximum gain. This is obtained with a maximum injector length from which one U shape is designed. The key feature of the cell design is a PNP transistor designed with an U shape which maximizes the injector surface and takes advantage of merged contacts to keep the cell size at a minimum (900 mm ). Advantages: - The b of the PNP transistors is maximized due to the great length and the small surface of the injector hence, (vertical injection is minimized).

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Harper PNP Cell Designed With U-Shaped PNP Injector for High Beta

This article describes the realization of an unsaturated Harper PNP cell in bipolar technology with polysilicon base and trench isolation. The well-known Harper cell (half) is depicted in Fig. 1, and the novel implementation is shown in Fig. 2. The collector of the lateral PNP transistor is designed to have a maximum gain. This is obtained with a maximum injector length from which one U shape is designed. The key feature of the cell design is a PNP transistor designed with an U shape which maximizes the injector surface and takes advantage of merged contacts to keep the cell size at a minimum (900 mm ). Advantages: - The b of the PNP transistors is maximized due to the great length and the small surface of the injector hence, (vertical injection is minimized). - The poly base of the NPN transistor may be connected with the collector of the PNP transistor. - The Schottky barrier diode guard ring is integrated with the PNP collector. - The bit line covers about 50% of the recessed oxide isolation (ROI) region, and therefore its capacitance is reduced.

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