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Transconductance in Silicon Gate Nitride Oxide IGFET

IP.com Disclosure Number: IPCOM000075374D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Dockerty, R: AUTHOR [+2]

Abstract

A high-temperature anneal in hydrogen increases the transconductance of a silicon gate nitride-oxide insulated gate field-effect transistor (IGFET) by reducing the fast-state density in the gate insulator. The hydrogen anneal is done as the last high-temperature step before the aluminum deposition step.

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Transconductance in Silicon Gate Nitride Oxide IGFET

A high-temperature anneal in hydrogen increases the transconductance of a silicon gate nitride-oxide insulated gate field-effect transistor (IGFET) by reducing the fast-state density in the gate insulator. The hydrogen anneal is done as the last high-temperature step before the aluminum deposition step.

Fast states in the gate insulator reduce the transconductance of an IGFET. A hydrogen anneal reduces the fast-state density in a nitride-oxide insulator when the nitride is directly exposed to the hydrogen ambient. This anneal is not possible in the silicon gate process because the anneal must be done after all other high-temperature steps (greater than 500 degrees C) have been done (e.g. poly silicon deposition and source-drain diffusion).

The hydrogen anneal is done as the last high-temperature step before aluminum metallurgy is deposited on the wafer. At this point the gate insulator is covered with a polycrystalline silicon gate and an insulating layer of pyrolytic silicon dioxide. A 0.5 hour anneal at a temperature between 800 degrees C and 1100 degrees C significantly reduces the fast-state density.

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