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Fabricating Shallow Junction Semiconductor Devices

IP.com Disclosure Number: IPCOM000093636D
Original Publication Date: 1967-Nov-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Dhaka, VA: AUTHOR [+2]

Abstract

This process permits fabrication of semiconductor devices having high doping levels and accurate junction depth control in the order of .004 mils.

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Fabricating Shallow Junction Semiconductor Devices

This process permits fabrication of semiconductor devices having high doping levels and accurate junction depth control in the order of .004 mils.

In one form, semiconductor devices are obtained by depositing an impurity upon the wafer at a low temperature so that practically no diffusion takes place during the steps. For example, phosphorus pentoxide can be deposited upon the wafer in glass form at 700-750 degrees C using phosphorus pentoxide or phosphorus oxychloride as a source. Next, rapidly increasing the temperature of the wafer to the diffusion temperature and diffusing the impurity onto the wafer are effected. The temperature can be increased for a short time, 1 to 2 minutes, at the diffusion temperature, typically 970 degrees C. The process may be further improved by preheating the wafer to 750-800 degrees C before the rapid heating to 970-1150 degrees C. The higher temperature of diffusion is necessary because otherwise the solubility of the impurity becomes small and ability to dope to the desired level is lost.

High performance devices have very shallow junctions. At the high temperature of diffusions, where the diffusion constant is high, the diffusion can be allowed to take place for only a short period of time. Typically a total time of heat cycling at 970 degrees C with a predeposited source produces a junction depth of .004 mils with a surface concentration of 2.5 x 10/21/ atoms/cc.

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