Reactor optimized for chemical vapor deposition of titanium

Abstract

A plasma reaction chamber particularly suited for plasma-enhance chemical vapor deposition of titanium using TiCl.sub.4 as the precursor. The reactor includes a perforated showerhead faceplate and a perforated blocker plate within the showerhead to evenly distribute the atomized TiCl.sub.4. Both the showerhead faceplate and the blocker plate are made of solid nickel. RF power is applied between the showerhead faceplate and the heater pedestal supporting the wafer to excite the processing gas into a plasma. A shield ring is set on the periphery of the heater pedestal to confine the plasma to the processing region above the wafer. The shield ring is supported on the heater pedestal by a downwardly descending ridge, thereby minimizing thermal flow. The shield ring also protects the periphery of the top surface of the heater pedestal not covered by the wafer. An isolator electrically insulates the RF-driven showerhead from the chamber body and is disposed generally above the shield ring. The bottom of the isolator and the top of the shield ring are similarly curved with a nearly constant gap between them. The small gap creates a flow choke between the processing region and an annular pumping channel. The curve of the gap prevents the plasma from extending into the pumping channel. The bottom of the chamber below the heater pedestal is covered with a quartz thermal shield insert to reduce the flow of heat to the chamber wall. A lift ring for raising lift pins selectively lifting the wafer is also composed of quartz.