Integrated Dynamic Simulation of Rapid Thermal Chemical Vapor Deposition of Polysilicon
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A physically-based dynamic simulator has been constructed to investigate the time-dependent behavior of equipment process, sensor, and control system for rapid thermal chemical vapor deposition (RTCVD) of polysilicon from SiH4. The simulator captures the essential physics and chemistry of mass transport, heat transfer, and chemical kinetics of the RTCVD process as embodied in equipment. In order to complete the system-level description, reduced-order models are also employed to represent processes involving high complexity of physics. Integration of individual simulator elements for equipment, process, sensors, and control systems enables the evaluation of not only the deposition rate and film thickness, but also of a broad range of dynamic system properties such as equipment performance, gas flow conditions, wafer temperature variation, wafer optical properties (absorptivity/emissivity), gas composition in reactor, total process cycle time, consumables volume, and reactant utilization. This makes the simulator directly applicable to the optimization of process recipe and equipment design, to process control strategy, and to fault classification. This case study of polysilicon RTCVD demonstrates (1) that integrated dynamic simulation is a versatile tool for representing system-level dynamics, and (2) that such representation is pivotal in successful application of modeling and simulation for manufacturing optimization and control.