Structural and Electrical Effects on (A1-Si)/n+Si Ohmic Contact of in Situ Silicon Cleaning by Ar Ions Bombardment

In situ etching of native Si02 by Ar+ ion bombardment before metal sputter deposition can increase the contact resistance of the metal-semiconductor contact. This is commonly attributed to surface contamination produced by various mechanisms or to etch-induced surface damage. In this paper, in order to elucidate the cause of the increase of contact resistance, we have studied (Al-Si)/n+Si contacts prepared by various treatments of the Si surface. We attribute the higher postalloy contact resistance of the sputter etched contacts to the existence of an Al doped layer which formation was induced by the preexisting disordered layer created by the Ar+ ion bombardment.