Analysis of transition metal induced surface defects in silicon following apid thermal processing

Abstract

Rapid Thermal Processing(RTP) is extensively used in VLSI technology for implant activation, licidation, oxidation, and passivation glass reflow. The diffusion of back-side depositions of transition metals during rapid thermal annealing and the resulting front-side defect formation in silicon has recently been investigated by several authors but a detailed analysis of the defect structure, morphology, and chemistry is lacking. The defect structure and chemistry on both the front and back sides of the wafers ter RTA were investigated by TEM on plan-view and cross-section foils. A Philips EM430 microscope ierating at 300 KeV and a Hitachi H-800 microscope operating at 200 KeV were used. Ni and Cu sputter deposited on the back-side of 4 inch diameter (100) Si wafers were diffused for 10 sec at 1150°C in trogen ambient. The thickness of the metal film was 50 nm. A Heatpulse 2101 RTA system was used.Fig. 1 is a CDF micrograph showing a group of precipitates on the front surface of a sample nickel diffused from the back surface.