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End Point Detection for Reactive Ion Etching

IP.com Disclosure Number: IPCOM000088613D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Geipel, HJ: AUTHOR

Abstract

This is a technique to stop etching of oxide materials exactly at the silicon dioxide-silicon interface on the surface of a semiconductor diode during reactive ion etching. The reactive ion plasma, which performs the etching, together with the diode, forms an RF tuned generator. A strobe light, directed onto the region being etched will, when the surface of the semiconductor is exposed, cause a signal to be generated that will change the tuning of the RF generator. This generated signal is fed into an amplifier such that when the silicon dioxide is completely removed and the silicon surface is exposed the signal level changes at the output of the locked-in amplifier which stops the reactive ion etchant process.

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End Point Detection for Reactive Ion Etching

This is a technique to stop etching of oxide materials exactly at the silicon dioxide-silicon interface on the surface of a semiconductor diode during reactive ion etching. The reactive ion plasma, which performs the etching, together with the diode, forms an RF tuned generator. A strobe light, directed onto the region being etched will, when the surface of the semiconductor is exposed, cause a signal to be generated that will change the tuning of the RF generator. This generated signal is fed into an amplifier such that when the silicon dioxide is completely removed and the silicon surface is exposed the signal level changes at the output of the locked-in amplifier which stops the reactive ion etchant process.

In present etching technology reactive ion etching has become increasingly effective and more interesting. In the production of most semiconductor devices it is required that a silicon dioxide layer directly above a silicon surface be removed or etched away. Unfortunately, reactive ion etching etches both silicon dioxide and silicon at about the same rate. Therefore, it is difficult to determine when the silicon dioxide-silicon interface is reached. This technique eliminates this uncertainty and permits exact interface determination.

A typical reactive ion etching apparatus configuration is shown schematically in the drawing. A wafer 10, containing a junction 10a and having a silicon dioxide layer 11 and a mask...