Title :
Decoupled flux control for molecular beam epitaxy
Author :
Garrett, Patrick H. ; Heyob, Jeffrey J. ; Hunt, Victor J. ; LeClair, Steven R. ; Patterson, Oliver D.
Author_Institution :
Dept. of Electr. & Comput. Eng., Cincinnati Univ., OH, USA
fDate :
11/1/1993 12:00:00 AM
Abstract :
Improvement of the manufacturing capability for the molecular beam epitaxy (MBE) process is demonstrated with respect to the consistent achievement of effusion cell flux stability of 1% of setpoint values. This performance was obtained by decoupling the principal sources of flux variability from each cell temperature control system including: cell shutter opening flux disturbances with implementation of a feedforward compensator that precisely cancels evaporant mass enthalpy transients; electric power frequency-correlation flux disturbances with substitution of heater DC drivers for the standard AC triac drivers; and flux process disorder resulting from coupled temperature controller proportional-integral-derivative (PID) tuning values with identification of decoupled trapezoidal PID tuning values
Keywords :
molecular beam epitaxial growth; process control; semiconductor device manufacture; semiconductor epitaxial layers; semiconductor growth; temperature control; three-term control; PID tuning; cell shutter opening flux disturbances; cell temperature control system; coupled temperature controller; effusion cell flux stability; electric power frequency-correlation flux disturbances; feedforward compensator; flux process disorder; flux variability; heater DC drivers; manufacturing capability; mass enthalpy transients; molecular beam epitaxy; setpoint values; Frequency; Manufacturing processes; Molecular beam epitaxial growth; Pi control; Stability; Temperature control; Three-term control; Thyristors; Tuning; Weight control;
Journal_Title :
Semiconductor Manufacturing, IEEE Transactions on
