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Selective Epitaxial/Quasi-Epi Emitters

IP.com Disclosure Number: IPCOM000060369D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Li, GP: AUTHOR [+4]

Abstract

In the manufacture of polysilicon emitters in semiconductor devices the conventional method involves a blanket poly-Si deposition and a subsequent lithographic masking to remove it from unwanted regions. This article proposes to selectively deposit silicon in the emitter opening only. This would lead to process simplification since it would eliminate the need for the lithography and etch steps. Under conventional practices the N+ poly contact 1 (Fig. 1) to the emitter 4 is deposited using an homogeneous chemical vapor deposition (CVD) process to deposit the poly-Si. Since the poly films grow over the whole surface of the wafer, a mask-and-etch step is needed to define the edge of the N+ poly. The spacing 5 between the emitters is limited by the alignment tolerance of the N+ poly and the metal 2.

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Selective Epitaxial/Quasi-Epi Emitters

In the manufacture of polysilicon emitters in semiconductor devices the conventional method involves a blanket poly-Si deposition and a subsequent lithographic masking to remove it from unwanted regions. This article proposes to selectively deposit silicon in the emitter opening only. This would lead to process simplification since it would eliminate the need for the lithography and etch steps. Under conventional practices the N+ poly contact 1 (Fig. 1) to the emitter 4 is deposited using an homogeneous chemical vapor deposition (CVD) process to deposit the poly-Si. Since the poly films grow over the whole surface of the wafer, a mask-and-etch step is needed to define the edge of the N+ poly. The spacing 5 between the emitters is limited by the alignment tolerance of the N+ poly and the metal 2. It is proposed to deposit the N+ poly by means of a selective heterogeneous growth process (solid-gas) so that the silicon N+ contact would be selective and grow only on the silicon surface exposed. The growth could be either polysilicon, quasi-epitaxial, or fully epitaxial. The N+ poly or quasi- epi film which would be required is on the order of 100-150 nm in thickness. This means a short deposition time on the order of 1 minute when using an epitaxial reactor at 900-1000OEC. A reaction system which includes Si-H-Cl as reactants is required to provide heterogeneous growth and selective growth. The temperature range can be chosen by...