Accurate Thickness Deposition Control for Chrome Evaporation
Original Publication Date: 1980-Jul-01
Included in the Prior Art Database: 2005-Feb-13
Thin film metals evaporation techniques employed in semiconductor processing commonly utilize a shutter placed between the source and the substrates which prevent the substrates from being coated by the evaporant during the source heat-up (see Fig. 1). A rate monitor or controller (controller 1, Fig. 1) is typically placed in a position near the substrates to be coated so as to accurately measure the rate of deposition and thickness of the coating on the substrate. When the shutter is swung to one side, the rate monitor/controller is subjected to an instantaneous increase in the evaporation rate. If the rate of evaporation is significantly greater or smaller than the control set point, there will be large fluctuations in the input power to the evaporant source.