Influence of gas composition on wafer temperature in a tungsten chemical vapor deposition reactor: Experimental measurements, model development, and parameter identification

Experimental measurements of wafer temperature in a single-wafer, lamp-heat ed chemical vapor deposition system were used to study the wafer temperatur e response to gas composition. A physically based simulation procedure for the process gas and wafer temperature was developed in which a subset of pa rameter values were estimated using a nonlinear, iterative parameter identi fication method, producing a validated model with true predictive capabilit ies. With process heating ramp power held constant, wafer temperature varia tions of up to 160 K were observed by varying the feed gas H-2/N-2 ratio. H eat transfer between the wafer and susceptor was studied by shifting the in strumented wafer off the susceptor axis, exposing a portion of the wafer ba ckside to the chamber floor. Model predictions and experimental observation s both demonstrated that the gas velocity field had little influence on the observed wafer and predicted gas temperatures. (C) 2001 American Vacuum So ciety.