Optical Emission

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Monitoring of reactive species or etch by-products provides endpoint signal.

Endpoint relies on etch stop layer.

Scanned monochromator allows full spectrum analysis.

Optical emission is also recommended for
system "fingerprinting".



Trace achieved when etching SiOx layers down to a Si substrate.

It shows a typical trace obtained when etching SiOx layers down to a Si substrate. The large picture shows the full emission spectra of the plasma. The blue and red marker lines correspond to the emission peaks of CO, which is an SiOx etch by-product, at 483 nm and 520 nm.
The small graph in the top right hand corner shows the fall in the intensity of these CO etch by-product emission peaks, as the last SiOx is removed. By monitoring the time derivative of this CO emission intensity it is possible to obtain a very reliable endpoint trigger.

single beam laser interferometry

SiO2 via hole ething


laser interferometry for the Bosch process