16 April 1993 Closed-loop temperature control system for a low-temperature etch chuck
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Proceedings Volume 1803, Advanced Techniques for Integrated Circuit Processing II; (1993) https://doi.org/10.1117/12.142927
Event: Microelectronic Processing '92, 1992, San Jose, CA, United States
Abstract
A closed-loop temperature control system has been developed for use in a low-temperature (-135 degree(s)C) plasma etch system. The system employs an optical fluorescence probe on the chuck (a second probe monitors the wafer temperature as well) to provide feedback to the heating element on the input line of the chuck closed-loop coolant fluid. A simple proportional-integral-derivative (PID) controller with a learn mode controls the rate of current pulses applied to the heater. Innovations include the direct measurement of chuck temperature for the control signal, and the coupling of large cooling and heating capacities in close proximity to the chuck along with a fast fluid flow to guarantee quick response. The system has been tested in prolonged etch runs of many wafers. It provides reliable, tight temperature control (3(sigma) as low as 0.6 degree(s)C). This level of control is significantly tighter than could be achieved by merely monitoring chiller bath temperatures.
© (1993) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
D. Rex Wright, Wayne D. Clark, Dennis C. Hartman, U. C. Sridharan, Martin Kent, Ralph C. Kerns, "Closed-loop temperature control system for a low-temperature etch chuck", Proc. SPIE 1803, Advanced Techniques for Integrated Circuit Processing II, (16 April 1993); doi: 10.1117/12.142927; https://doi.org/10.1117/12.142927
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