Selective etching and epitaxial refilling of silicon wells in the system SiH4/HCl/H2

Wells were etched in (100) silicon by different kinds of selective etching and were selectively refilled by using different gas systems. Masking materials were SiO₂ and Si₃N₄; for the refilling the systems SiCl₄/H₂ and SiH₄/HCl/H₂ were studied. By using a combination of weak anisotropic gas etching with HCl (Si₃N₄ films as mask) and of SiH₄/HCl/H₂ as refilling system, plane surfaces without ridges at the boundary of the mask and without nuclei on the mask were reached. The results were obtained by SEM, light microscopic and profile investigations and are compared with the other kinds of etching and refilling.