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Harper PNP Cell Layout With Improved PNP Characteristics

IP.com Disclosure Number: IPCOM000046415D
Original Publication Date: 1983-Jul-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Cullet, R: AUTHOR [+3]

Abstract

In a Harper PNP cell such as described in the IBM Technical Disclosure Bulletin 23, 1473-1474 (September 1980), the PNP transistor injector is surrounded on three sides with P+ isolation which creates a parasitic PNP lateral transistor. The layout shown in the drawing allows the parasitic hole current from the injector of this lateral PNP to the P+ substrate to be reduced.

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Harper PNP Cell Layout With Improved PNP Characteristics

In a Harper PNP cell such as described in the IBM Technical Disclosure Bulletin 23, 1473-1474 (September 1980), the PNP transistor injector is surrounded on three sides with P+ isolation which creates a parasitic PNP lateral transistor. The layout shown in the drawing allows the parasitic hole current from the injector of this lateral PNP to the P+ substrate to be reduced.

As shown in Fig. 1A, the PNP injector is diffused behind the reach-through diffusion. In that way the lateral hole injection is cut down since the lateral side of the injector I is abutted against the recessed oxide isolation pocket (ROI). The two transverse sides of the injector I have been pushed back with respect to the P+ bottom isolation by a local narrowing of the ROI pocket.

Implementing this principle in the Harper PNP cell shown in Fig. 1B leads to the cell layout shown in Fig. 1C. A cross section of half a cell is shown in Fig. 1D.

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