Improvement of Czochralski Silicon Wafers By

High- temperature anneal ing in hydrogen, argon, and oxygen ambients improves the electrical per formance of Czochralski Si wafers considerably. The gate oxide integrity of such wafers can approach values close to 100 % yield after anneal ing for 1 to 2 h at 1200 ~ in argon and hydrogen ambient wh ich is related to a significant reduction of near-surface crystal defects as compared to nonannea led polished wafers. The perfection of epitaxial wafers is, however, not obtained. The high-temperature treatment deteriorates the surface of polished wafers depending on the ambient used. A protective oxide layer g rown during anneal ing in an oxygen ambient prevents roughening due to desorption of SiO. A more pro-nounced roughening occurs by anneal ing in hydrogen or argon wh ich is tightly connected to the chemical composit ion of the Surface. A hydrogen terminated 2 • ] reconstructed Si (i00) surface is observed after annealing in hydrogen. An oxygen-denuded zone is fo rmed close to the surface during high-temperature annealing preventing oxygen precipitation in this region of the wafer. The oxygen precipitation in the bulk of the wafers depends significantly on the details of the anneal ing process. A precipitation behavior similar to nonannea led Si wafers can be obtained by appropriate process parameters