A Novel Method for In Situ Estimation of Hg1−x Cd x Te Etch Rate in Real Time

A novel and noninvasive method to determine the in situ etch rate (ER) of inductively coupled plasma (ICP)-etched Hg1−x Cd x Te in real time is described. Various relevant output parameters from the ICP tool were analyzed with the goal of finding correlations with the Hg1−x Cd x Te ER. Of the parameters analyzed, the most promising is the chuck direct-current (DC) bias voltage. Correlations between the chuck DC bias voltage and two different types of Hg1−x Cd x Te detector wafers are reported with a correlation coefficient of R > 0.94. Analyses of these results are presented. Estimates of the Hg1−x Cd x Te ER for all the samples based on the new method are presented and compared with the actual ER. The results show less than 3% differential between the actual and estimated ER.