CONTAMINATION CONTROL OF POLYSILICON GATES IN A VERTICAL REACTOR CLUSTER TOOL

This paper demonstrates that defect control is greatly improved when u sing the protected environment of a vertical reactor cluster tool comp rising a preclean station. The cluster tool investigated combines the established process stability of vertical reactors with new capabiliti es as native oxide removal, ultraclean wafer transport, and reactors s hielded from environmental contamination. An adequate combination of c lean gas usage and leak tightness makes it possible to apply HF vapor etching effectively in order to control the properties of the silicon- silicon oxide interface. For different precleaning conditions, interfa ce and bulk contamination was measured, the sources identified, and th e effect of improvements monitored. To this end, several electrical pa rameters were determined, including the analysis of Q(bd) and E(bd). Q uantitative TXRF and SIMS techniques were used to correlate the result s with metallic and organic contamination.