APPLICATION OF UV RADIATION IN PRE-OXIDATION TREATMENTS OF SILICON WAFERS.

As the thickness of gate oxides employed in high density MOS integrated circuits decreases, attention must be given to the condition of the silicon surface prior to the thermal gate oxidation process. The interaction of chemically cleaned silicon surfaces with atomic oxygen generated from molecular oxygen either by ultraviolet radiation or by a microwave discharge is proposed and studied as a preoxidation treatment. The goals of this treatment are improved oxide thickness precision and an improvement in the overall quality of such thin, less than 15 nm, gate dielectrics. The results demonstrate the feasibility of achieving reduced carbon content at the SiO//2-Si interface and, providing the conditions of UV treatment are appropriately selected, reduced oxide charge density and improved oxide integrity.