Browse Prior Art Database

Single Epitaxial Layer Pedestal Device

IP.com Disclosure Number: IPCOM000075682D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Magdo, IE: AUTHOR [+2]

Abstract

There is shown several pedestal device structures which can be built using a single epitaxial layer. Figs. A and B show, respectively, the horizontal and vertical geometries of one form of the structure. In order to avoid punchthrough to occur between the base and the substrate, one can either do a shallow N- as a blanket diffusion into the P substrate or an N- epi on top of the substrate. The space between isolation and base diffusion is used for the collector "ring". The distance between isolation and subcollector can be 0.2 mils, while the distance between base and isolation has to be 0.3 mils to avoid punchthrough. The collector series resistance will be somewhat increased, but can be balanced by a deeper or wider subcollector diffusion.

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Single Epitaxial Layer Pedestal Device

There is shown several pedestal device structures which can be built using a single epitaxial layer. Figs. A and B show, respectively, the horizontal and vertical geometries of one form of the structure. In order to avoid punchthrough to occur between the base and the substrate, one can either do a shallow N- as a blanket diffusion into the P substrate or an N- epi on top of the substrate. The space between isolation and base diffusion is used for the collector "ring". The distance between isolation and subcollector can be 0.2 mils, while the distance between base and isolation has to be 0.3 mils to avoid punchthrough. The collector series resistance will be somewhat increased, but can be balanced by a deeper or wider subcollector diffusion. The structure reduces isolation capacitance, as compared to a double-epitaxial layer structure.

Figs. C and D show alternate horizontal geometries for single-epitaxial layer devices.

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