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Elimination of Interfacial Barrier in Diffusion of Boron From Polysilicon Into Single Crystal for Base Diffusion

IP.com Disclosure Number: IPCOM000043145D
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Burkhardt, PJ: AUTHOR

Abstract

This approach suggests the use of a technique which forms a protective monolayer of chemisorbed iodine over a freshly etched silicon surface in order to prevent the formation of any surface film prior to the deposition of a polysilicon base. The presence of such films could be the cause of subsequent diffusion barrier problems during the base diffusion. The technique as taught by R. Lieberman and D. L. Klein [*] involves dipping the wafer into a solution of iodine in an anhydrous solvent. The iodine chemisorbs on the surface and also displaces other contaminant ions, such as F and water, by the law of mass action. The wafer is withdrawn and dried. The iodine layer protects the surface until the wafer is placed in the polysilicon deposition furnace.

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Elimination of Interfacial Barrier in Diffusion of Boron From Polysilicon Into Single Crystal for Base Diffusion

This approach suggests the use of a technique which forms a protective monolayer of chemisorbed iodine over a freshly etched silicon surface in order to prevent the formation of any surface film prior to the deposition of a polysilicon base. The presence of such films could be the cause of subsequent diffusion barrier problems during the base diffusion. The technique as taught by R. Lieberman and D. L. Klein [*] involves dipping the wafer into a solution of iodine in an anhydrous solvent. The iodine chemisorbs on the surface and also displaces other contaminant ions, such as F and water, by the law of mass action. The wafer is withdrawn and dried. The iodine layer protects the surface until the wafer is placed in the polysilicon deposition furnace. As it heats up in the furnace, the iodine layer desorbs above N500OEC, leaving a clean silicon surface immediately prior to polysilicon deposition. Reference [*] R. Lieberman and D. L. Klein, "Temporary Protection of Silicon Surfaces by Iodine Films," Journal of Electrochemical Society 113, 956-958 (September 1966).

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