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Oxide Prevention of Si Surfaces Using Iodine Saturated Immiscible Solvents

IP.com Disclosure Number: IPCOM000074278D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Hovel, HJ: AUTHOR

Abstract

One of the major difficulties in silicon epitaxy, especially at low temperatures, resides in eliminating the unwanted silicon dioxide layer that automatically forms on a freshly etched silicon surface upon exposure to air or water.

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Oxide Prevention of Si Surfaces Using Iodine Saturated Immiscible Solvents

One of the major difficulties in silicon epitaxy, especially at low temperatures, resides in eliminating the unwanted silicon dioxide layer that automatically forms on a freshly etched silicon surface upon exposure to air or water.

One known method of confronting the problem is by removing the silicon from the etchant and, as quickly as possible, dipping it into an anhydrous solvent, such as, methanol or carbon tetrachloride saturated with iodine. If done rapidly enough iodine bonds loosely to the surface in place of oxygen. The iodine can then be removed by heating in vacuum or inert gas prior to epitaxy.

The method described here proposes that an immiscible solvent, such as trichlorethylene, which has been saturated with iodine be poured into the etching solution prior to the removal of the silicon being etched thereat. Thus, a silicon wafer, which is being etched by hydrofluoric acid, for example, may be prevented from oxidizing by pouring the trichlorethylene into the hydrofluoric acid. The solvent acts to lift the hydrofluoric away from the silicon surface by replacement, whereby iodine is absorbed on the silicon surface as the hydrofluoric acid is being replaced. The hydrofluoric floats to the surface of the solvent and may be poured off.

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