Browse Prior Art Database

Deep Boron Channel Stop

IP.com Disclosure Number: IPCOM000041846D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

El-Kareh, B: AUTHOR [+2]

Abstract

A simple process is provided for introducing a channel stop implant into a semiconductor substrate at an early stage to avoid lateral scattering of the implanted material. The process, which may be used effectively when making bipolar static random-access memories, also provides reduced substrate resistivity, if necessary, without increasing subcollector-to-substrate capacitance, while providing a beneficial impact to soft error rate problems. For a better understanding of the process, reference may be had to the figure which shows a P- conductivity-type semiconductor substrate or wafer 10 of high resistivity. A screen oxide layer (not shown) of approximately 250 angstroms is grown and an N+ subcollector region 12 is ion implanted.

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Deep Boron Channel Stop

A simple process is provided for introducing a channel stop implant into a semiconductor substrate at an early stage to avoid lateral scattering of the implanted material. The process, which may be used effectively when making bipolar static random-access memories, also provides reduced substrate resistivity, if necessary, without increasing subcollector-to-substrate capacitance, while providing a beneficial impact to soft error rate problems. For a better understanding of the process, reference may be had to the figure which shows a P- conductivity-type semiconductor substrate or wafer 10 of high resistivity. A screen oxide layer (not shown) of approximately 250 angstroms is grown and an N+ subcollector region 12 is ion implanted. Alternatively, the oxide layer may be selectively etched, followed by a diffusion step to form region 12. After introducing the impurities into subcollector region 12, a deep Pregion 14 is defined by implanting boron ions at, e.g., an energy of 3 MeV and a dose of 3x1013 atoms/cm2 . An N type conductivity epitaxial layer 16 is grown over N+ subcollector region 12, and by using known reactive ion etching techniques, a trench 18 is formed which extends through epitaxial layer 16 and subcollector region 12 into the deep boron region 14 of substrate 10. The surface of trench 18 is oxidized and filled with appropriate insulating material 20, such as oxide and polysilicon. The structure is now provided with appropriat...