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Epitaxial Thickness Adjustment

IP.com Disclosure Number: IPCOM000075382D
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

Lin, PT: AUTHOR [+2]

Abstract

The control of epitaxial layer thickness becomes very critical for many devices. It has been found that the epitaxial layer thickness can be adjusted to an accuracy in the order of 100 angstroms by either introducing an anodic oxidation step or a low-temperature reoxidation cycle after the epitaxial layer is grown, followed by an etching step. The low-temperature reoxidation alternative involves the use of the conventional thermal oxidation process using steam and oxygen at an elevated temperature.

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Epitaxial Thickness Adjustment

The control of epitaxial layer thickness becomes very critical for many devices. It has been found that the epitaxial layer thickness can be adjusted to an accuracy in the order of 100 angstroms by either introducing an anodic oxidation step or a low-temperature reoxidation cycle after the epitaxial layer is grown, followed by an etching step. The low-temperature reoxidation alternative involves the use of the conventional thermal oxidation process using steam and oxygen at an elevated temperature.

The preferred process uses anodic oxidation. An example of a suitable anodic oxidation process uses a solution of 500 ml. N-methylasidimide, 0.5 grams potassium nitrate (KNO(3)), and 15 ml. water. The backside of the silicon wafer to be anodized in the solution is connected to a positive potential through a graphite block. A negative electrode is immersed in the solution. A layer of oxide is grown on the silicon wafer once the battery is connected. With sufficient current density, a uniform oxide layer can be formed within a very short time. The process produces 1000 angstroms silicon dioxide grown on a silicon wafer with 1 cm/2/ area in 40 seconds with a power supply of 170 volts and current of 20 amperes.

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