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Anneal for Removing Surface States in Shallow Junction Devices

IP.com Disclosure Number: IPCOM000077973D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Berman, A: AUTHOR

Abstract

Surface states in field-effect transistors present serious problems, since they shift the threshold voltage and reduce the transconductance of the device. Annealing steps for removing the surface states are known which also frequently degrade the junction quality.

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Anneal for Removing Surface States in Shallow Junction Devices

Surface states in field-effect transistors present serious problems, since they shift the threshold voltage and reduce the transconductance of the device. Annealing steps for removing the surface states are known which also frequently degrade the junction quality.

This annealing technique serves to remove surface states without materially degrading the junctions. In the method, prior to deposition of the metallurgy, the wafer is annealed in a forming gas at 500 degrees C for approximately 30 minutes. Subsequently, the metallurgy, typically aluminum, is deposited without introducing excessive density of surface states. The device with the metallurgy is then further annealed in a forming gas at 300 degrees C for one hour. The final anneal step may be modified depending on the junction depth. A longer annealing time at 275 degrees C can be used for shallower junction, that is, less than 5,000 Angstroms.

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