Browse Prior Art Database

Method of Wet Etch Control

IP.com Disclosure Number: IPCOM000083343D
Original Publication Date: 1975-May-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bickford, HG: AUTHOR [+2]

Abstract

Previously in the wet etching of semiconductor material such as silicon wafers, control of etching processes has been accomplished by providing a timer which allows etching to continue for a predetermined length of time. Laser and electronic probe techniques have also been utilized. These methods give no indication of how fast etching is progressing, nor do they compensate for changes in etchant concentration, temperature, pH, or other variables affecting the etching rate of the etchant. Thermal inertia of these systems does not allow simple feedback control.

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Method of Wet Etch Control

Previously in the wet etching of semiconductor material such as silicon wafers, control of etching processes has been accomplished by providing a timer which allows etching to continue for a predetermined length of time. Laser and electronic probe techniques have also been utilized. These methods give no indication of how fast etching is progressing, nor do they compensate for changes in etchant concentration, temperature, pH, or other variables affecting the etching rate of the etchant. Thermal inertia of these systems does not allow simple feedback control.

Sensitivity of the chemical etching reaction to temperature is said to be 8% per degree centigrade as a general rule.

An accurate, precise, and new method for etch control, especially where increased device line densities and decreasing line widths in the magnitude of 100 microinches is required, comprises sensing the actual temperature of the etchant solution or stream in a dynamic system at a point in close proximity to the area being etched, and computer calculate the momentary etch rates as a function of temperature.

Setting the desired thickness or extent of etch as a limit for integration, the computer terminates the etching and starts quenching or rinse automatically. Any suitable apparatus is useful and not limiting to this concept.

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