Metals contamination in high and medium current implanters

Abstract

As +, 80 keV implants at specification beam currents were conducted on both the Varian E1000 and E220/E500 implanters to study metals contamination. The E1000 was configured with a silicon coated disc and spill-over cup and a newly designed low particulate acceleration column, with a graphite entrance collimator and a graphite exit electrode. The E220/E500 was configured with a metals reduction kit and, in one implant, with an experimental silicon coated acceleration tube. TXRF and SIMS measurements were performed on the implanted wafers. A TRIM based approximation was developed to analyze the aluminum contamination of 132 ppm, all of which was non-energetic. On the E220.2500 with the metals reduction kit the value was 91 ppm, with some energetic contribution. When the experimental silicon coated electrode acceleration tube was studied the energetic contribution was eliminated. TXRF measurements for Ti, Cr, Fe, Ni, Cu, and Zn indicated little or no added contribution from these metals for both implanter types as compared to an unimplanted reference wafer.