Modeling and Simulation of a Tungsten Chemical Vapor Deposition Reactor

Abstract

Chemical vapor deposition (CVD) processes are widely used in semiconductor device fabrication to deposit thin films of electronic materials. Physically based CVD modeling and simulation methods have been adopted for reactor design and process optimization applications to satisfy the increasingly strigent processing requirements. In this research, an ULVAC ERA-1000 selective tungsten chemical vapor deposition system located at the University of Maryland was studied where a temperature difference as large as 120 oC between the system wafer temperature reading and the thermocoupled instrumented wafer measurement was found during the manual processing mode. The goal of this research was to develop a simplified, but accurate, three-dimensional transport model that is capable of describing the observed reactor behavior.A hybrid approach combining experimental and simulation studies was used for model development. Several sets of experiments were conducted to investigate the effects of process parameters on wafer temperature. A three-dimensional gas flow and temperature model was developed and used to compute the energy transferred across the gas/wafer interface. System dependent heat transfer parameters were formulated as a nonlinear parameter estimation problem and identified using experimental measurements. Good agreement was found between the steady-state wafer temperature predictions and experimental data at various gas compositions, and the wafer temperature dynamics were successfully predicted using a temperature model considering the energy exchanges between the thermocouple, wafer, and showerhead.