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Thermal Oxidation of Silicon for Variable Threshold FET Devices

IP.com Disclosure Number: IPCOM000074795D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Aboaf, JA: AUTHOR

Abstract

In variable threshold MNOS-FET memory devices, the most sensitive part is the thin thermal oxide (SiO(2)), 15-40 Angstroms thick. The writing process occurs via tunneling through the oxide and tunneling is exponentially dependent on thickness. It is most important to control this thickness accurately and for such control, slow growth rates are required. Silicon may be thermally oxidized as follows: Oxidize silicon wafers either with NO or with NO+H(2). The growth rate of the oxide in both cases is very low and can be carried out in a temperature range of 1000-1100 degrees C. For the NO+H(2) reaction at a 1000 degree C, the growth of an oxide between 22 Angstroms and 28 Angstroms thickness takes place in 90 minutes. In an ambient of O(2) of only 3000 parts per million, six minutes is the time required.

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Thermal Oxidation of Silicon for Variable Threshold FET Devices

In variable threshold MNOS-FET memory devices, the most sensitive part is the thin thermal oxide (SiO(2)), 15-40 Angstroms thick. The writing process occurs via tunneling through the oxide and tunneling is exponentially dependent on thickness. It is most important to control this thickness accurately and for such control, slow growth rates are required. Silicon may be thermally oxidized as follows: Oxidize silicon wafers either with NO or with NO+H(2). The growth rate of the oxide in both cases is very low and can be carried out in a temperature range of 1000-1100 degrees C. For the NO+H(2) reaction at a 1000 degree C, the growth of an oxide between 22 Angstroms and 28 Angstroms thickness takes place in 90 minutes. In an ambient of O(2) of only 3000 parts per million, six minutes is the time required. In an ambient of water vapor (45 millimeters pressure) less than three minutes is required. Other indirect actions such as CO(2)+H(2) can also be used.

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