No abstract

We have studied the etching of silicon, SiGe and germanium layers with gaseous HCl in reduced pressure-chemical vapour deposition (RP-CVD). We have observed the occurrence of two etch regimes depending on the etching temperature. The first regime takes place at high temperatures and is characterized by low activation energies (∼7 kcal mol −1 ), this whatever the germanium content of the etched layer. The other regime occurs at low temperatures and has associated high activation energies (which strongly depend upon the germanium concentration of the etched layer: 86 kcal mol −1 for pure Si versus 28 kcal mol −1 for pure Ge). Modifying the HCl partial pressure has different effects depending on the regime. In the high temperature regime, increasing the HCl partial pressure will almost quadratically increase the etch rate (ER ∝ P HCl 1.76), this both for Si and Si 0.67 Ge 0.33 . Meanwhile, the dependence is sub-linear in the low temperature regime (Si ER ∝ P HCl 0.53 and Si 0.67 Ge 0.33 ER ∝ P HCl 0.82