Table 2 Overview of the etching rates of Si and Si75Ge25 in PAA obtained by direct measurement of the sidewall-loss and indirect measurement of the spoke retraction. The errors represent the standard error of the slope. Last column shows the calculated selectivity ratios of Si75Ge25/Si
Si etch rate (nm/min) | SiGe etch rate (nm/min) | Selectivity (SiGe/Si) | ||||
|---|---|---|---|---|---|---|
Sidewall | Retraction | Sidewall | Retraction | Sidewall | Retraction | |
{111} | 0.66 ± 0.04 | 0.71 ± 0.05 | 8.3 ± 0.9 | 7.8 ± 0.4 | 12.6 | 11.0 |
{110} | 0.73 ± 0.03 | 0.76 ± 0.09 | 12.3 ± 0.7 | 10.8 ± 0.3 | 16.8 | 14.2 |