Etch Rate Predictor

It combines input from the HF monitor and operator input specifications to calculate and then provide in real-time a recommendation for the amount of HF or H2O to add to the bath. It adjusts and maintains the appropriate ratio of chemicals to achieve accurate etching of the wafers. This real-time process feedback can result in the reduction of, or even elimination of, process monitor wafers, which translates into considerable savings in operating expenses. Real-time monitoring makes closed loop solutions possible.


Inputs from the HF Monitor

HF concentration in weight percent

Inputs from the Operator

Total bath volume

Bath target HF to H2O mix ratio

Bath target temperature limits

Etch rate adjust factor

Feedback displayed from the Etch Rate

Inputs from the HF Monitor

Actual bath mix ratio

Actual bath temperature

Warning if the HF concentration is out of limit

Recommendation on how much HF or H2O to add (spike) if the mix ratio is out of limit

Estimated SiO2 etch rate


Valid for HF concentration ranges of .1 to 5.0 weight percent

Valid for HF bath temperatures from 14 to 34 degrees Celsius

Accuracy of estimated SiO2 etch rate is +/- 2% with proper etch adjustment factor 110 AC

Connection to the HF monitor with a 9 pin RS232 cable