EFFECTS OF PARTICLE CLOUDS IN A PLASMA ETCH SYSTEM ON SILICON DIOXIDEWAFER CONTAMINATION

Particle contamination of silicon dioxide wafers was studied in a Tega l MCR-1 etch system. The goal of the work was to understand the effect of ramping versus stepping the rf power and the effect of a magnetica lly induced local particle trap in close proximity to the wafer on waf er contamination. The effect of ramping the rf power versus not rampin g the rf power on wafer contamination was studied to test a hypothesis that ramping the power would cause a reduction in wafer contamination [G. S. Selwyn, J. E. Heidenreich, and K. L. Haller, J. Vac. Sci. Tech nol. A 9, 2817 (1991)]. For this reactor the results were inconclusive , but suggested that gas flow patterns played a dominant role. Wafers were passed through an etch process with and without a magnetically in duced particle trap. The results suggested particle deposition was inc reased in the presence of the trap, however, the number of particles a dded was of the same magnitude as the standard deviation.