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N+ Recombinant Collector Structure for Reduction of Soft Error Rates in Bipolar Random-Access Memory Cells

IP.com Disclosure Number: IPCOM000060140D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Voldman, SH: AUTHOR

Abstract

By extension of an N+ diffusion region 10, normally diffused above a P-base region 12 in construction of a pinch resistor 14, reduction of the soft error rate (SER) is achieved for a bipolar static random- access memory (RAM) which is sensitive to ionizing radiation, i.e., alpha particles tracking through a device region. A bipolar static RAM half-cell is shown in Fig. 1 in plan view. Charge collected at the base-collector and collector-p+ isolation junctions can destabilize the cell. To minimize this charge collection, the N+ diffusion region 10 is extended as indicated in Fig. 1 and in section A-A of Fig. 1 and may be further extended as shown in Fig. 2 with maximized dimensions t and minimized dimensions d.

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N+ Recombinant Collector Structure for Reduction of Soft Error Rates in Bipolar Random-Access Memory Cells

By extension of an N+ diffusion region 10, normally diffused above a P-base region 12 in construction of a pinch resistor 14, reduction of the soft error rate (SER) is achieved for a bipolar static random- access memory (RAM) which is sensitive to ionizing radiation, i.e., alpha particles tracking through a device region. A bipolar static RAM half-cell is shown in Fig. 1 in plan view. Charge collected at the base-collector and collector-p+ isolation junctions can destabilize the cell. To minimize this charge collection, the N+ diffusion region 10 is extended as indicated in Fig. 1 and in section A-A of Fig. 1 and may be further extended as shown in Fig. 2 with maximized dimensions t and minimized dimensions d. These extensions of the N+ diffusion region 10 increase the recombination of electron-hole pairs generated in the structure and minimize transport of charge through this region. The extended N+ region 10 also produces an electric field driving holes toward the subcollector. This field reduces the net charge collection at the junctions of concern. The structure of Fig. 2 also increases the capacitance of the cell at the collector-P+ isolation junction when the dimension L is minimized and at the base-collector junction when dimension d is minimized. The increased cell capacitance results in a higher critical charge (Qcrit) for a given cell size. This ap...