Enhanced process capability for sputtered ferroelectric films using low frequency pulsed dc and rf power supplies

Abstract

An improved sputtering method for sputter deposition from non-conducting metal oxide, ceramic, and ferroelectric targets is disclosed. Enhancements in deposition rate and composition control have been demonstrated using a pulsed DC sputtering method using a power supply in the frequency range of 100 to 250 KHz and a low frequency RF sputtering method using a power supply in the range of 200 to 500 KHz. The enhancement in composition control comes from an improvement in the sticking efficiencies of the volatile components in ferroelectric films. The low frequency and/or pulsed DC supplies provide lead content control for optimizing ferroelectric performance in pressure regimes that favor better cross wafer composition and thickness uniformity in PVD (Physical Vapor Deposition) sputtering tools. Because of the enhanced composition control, the low frequency pulsed DC and RF supplies can easily match the compositions generated by existing prior art high frequency RF approaches, but with significantly higher deposition rates and more favorable sputter pressure regimes. In addition to the improvements in process capability, the pulsed DC and low frequency supplies do not exhibit the radio frequency interference issues which typically plague RF sputter process repeatability and monitoring capabilities.