SiO2 planarization by two-step rf bias-sputtering

Abstract

A new angled-surface-moving model for surface planarization by rf bias sputtering is proposed. This planarization is achieved by angular selective etching of SiO2 films on top of metal stripes. A two-step rf bias-sputtering technique was developed, based on the new model. In this technique, the substrate bias voltage was changed in two steps during bias sputtering. The first step was to fill gaps without microcracks. The second step was to planarize at higher substrate bias. The planarized SiO2 layer surface, deposited on thermally oxidized Si wafers with Mo stripe patterns, had good flatness. A planarized 4-level metallization test structure was fabricated by the two-step rf bias-sputtering.