Anisotropic Si(100) etching induced by high translational energy Cl2 molecular beams

Abstract
Si(100) has been etched by high speed Cl2 molecular beams, generated by seeding in He. The translational energy dependence for etch rates has been measured by changing the gas mixing ratio and nozzle temperature. The two methods provided the same results. A 2.1 eV energy threshold was observed at 530 °C substrate temperature. The Cl+/Cl+2 intensity ratio, directly monitored by a quadrupole mass spectrometer, was independent of the nozzle temperature. These facts indicate that the etch rate enhancement is not attributed to Cl radicals or vibrationally excited Cl2 molecules. Owing to the translational energy induced etching, anisotropic etching profiles are realized at 670 °C substrate temperature.