Reactive Ion Etching in the Gaseous Electronics Conference RF Reference Cell

This paper describes the results of using the GEC reference cell as a reactive ion etcher. Silicon wafers with layers of polysilicon and silicon dioxide on crystaline silicon patterned with photoresist have been investigated with fluorine and chlorine chemistries. Scanning electron microscopy (SEM), profilometry, and refraction techniques were used to determine the etch parameters such as etch rate, uniformity and selectivity. The discharges are in general monitored by measuring the optical emission spectroscopy and the bias voltages. For fluorine chemistries, etch rates ranged from 5 nm/min to 177 nm/min, and for chlorine chemistries, etch rates ranged from 25 nm/min to 90 nm/min. Depending upon the discharge and chemistry conditions, similar etch rates and etch patterns of different GEC cells were obtained. Etch rates and relative fluorine concentrations obtained from a commercial etcher were compared to the GEC reference cell and were found to be similar although the GEC cell generally gave lower etch rates than the commercial etcher.