TRANSIENT HEAT-TRANSFER IN BATCH THERMAL-REACTORS FOR SILICON-WAFER PROCESSING

Precise thermal control; of multi-zone batch furnaces has become incre asingly important in semiconductor industry to prevent defect generati on during device fabrication. This work analyzes fundamental heat tran sfer processes during fast furnace ramping. Model simulations show two significant thermal features: (1) the radial temperature distribution on wafers follows a universal parabolic profile; and (2) a wafer stac k produces a strong cavity effect for thermal radiation. An engineerin g model is developed based on these features to characterize the depen dence of wafer temperature nonuniformity on processing conditions, inc luding the ramp rate and wafer spacing. This simple yet accurate model is useful for real-time process control. (C) 1998 Elsevier Science Lt d. All rights reserved.