Substrate temperature accuracy and temperature control flexibility in a molecular beam epitaxy system

Abstract

A control system and method for controlling temperatures while performing a MBE deposition process, wherein the control system comprises a MBE growth structure; a heater adapted to provide heat for the MBE deposition process on the MBE growth structure; and a control computer adapted to receive a plurality of dynamic feedback control signals derived from the MBE growth structure; switch among a plurality of control modes corresponding with the plurality of dynamic feedback control signals; and send an output power signal to the heater to control the heating for the MBE deposition process based on a combination of the plurality of control modes. In one embodiment, the plurality of dynamic feedback control signals comprises thermocouple signals and pyrometer signals.

1 . A computer-implemented method of controlling temperatures while performing a molecular beam epitaxy (MBE) deposition process, said method comprising:
 providing a heating sequence for said MBE deposition process on a MBE growth structure;   receiving, in a control computer, a plurality of dynamic feedback control signals derived from said MBE growth structure;   switching, in said control computer, among a plurality of control modes corresponding with said plurality of dynamic feedback control signals; and   sending an output power signal from said control computer to said MBE growth structure to control said heating for said MBE deposition process based on a combination of said plurality of control modes.   
   
   
       2 . The method of  claim 1 , wherein said plurality of dynamic feedback control signals comprises thermocouple signals and pyrometer signals. 
   
   
       3 . The method of  claim 2 , further comprising:
 receiving data related to material properties of said MBE growth structure;   selecting temperature values based on said material properties of said MBE growth structure;   heating said MBE growth structure based on the selected temperature values;   growing crystals on the heated MBE growth structure; and   cooling said MBE growth structure.   
   
   
       4 . The method of  claim 2 , further comprising performing a thermocouple calibration sequence on a thermocouple and a pyrometer monitoring said MBE growth structure. 
   
   
       5 . The method of  claim 2 , further comprising setting proportional integrating derivative (PID) control parameters in said control computer to set a level of said output power signal. 
   
   
       6 . The method of  claim 1 , further comprising:
 establishing output power signal levels in said control computer;   directly sending said output power signal levels from said control computer to a power supply unit; and   controlling temperatures in said MBE deposition process based on said output power signal levels.   
   
   
       7 . A program storage device readable by computer, tangibly embodying a program of instructions executable by said computer to perform a method of controlling temperatures while performing a molecular beam epitaxy (MBE) deposition process, said method comprising:
 providing a heating sequence for said MBE deposition process on a MBE growth structure;   receiving, in a control computer, a plurality of dynamic feedback control signals derived from said MBE growth structure;   switching, in said control computer, among a plurality of control modes corresponding with said plurality of dynamic feedback control signals; and   sending an output power signal from said control computer to said MBE growth structure to control said heating for said MBE deposition process based on a combination of said plurality of control modes.   
   
   
       8 . The program storage device of  claim 7 , wherein said plurality of dynamic feedback control signals comprises thermocouple signals and pyrometer signals. 
   
   
       9 . The program storage device of  claim 8 , wherein said method further comprises:
 receiving data related to material properties of said MBE growth structure;   selecting temperature values based on said material properties of said MBE growth structure;   heating said MBE growth structure based on the selected temperature values;   growing crystals on the heated MBE growth structure; and   cooling said MBE growth structure.   
   
   
       10 . The program storage device of  claim 8 , wherein said method further comprises performing a thermocouple calibration sequence on a thermocouple and a pyrometer monitoring said MBE growth structure. 
   
   
       11 . The program storage device of  claim 8 , wherein said method further comprises setting proportional integrating derivative (PID) control parameters in said control computer to set a level of said output power signal. 
   
   
       12 . The program storage device of  claim 7 , wherein said method further comprises:
 establishing output power signal levels in said control computer;   directly sending said output power signal levels from said control computer to a power supply unit; and   controlling temperatures in said MBE deposition process based on said output power signal levels.   
   
   
       13 . A control system for controlling temperatures while performing a molecular beam epitaxy (MBE) deposition process, said control system comprising:
 a MBE growth structure;   a heater adapted to provide heat for said MBE deposition process on said MBE growth structure; and   a control computer adapted to:
 receive a plurality of dynamic feedback control signals derived from said MBE growth structure; 
 switch among a plurality of control modes corresponding with said plurality of dynamic feedback control signals; and 
 send an output power signal to said heater to control said heating for said MBE deposition process based on a combination of said plurality of control modes. 
   
   
   
       14 . The control system of  claim 13 , wherein said plurality of dynamic feedback control signals comprises thermocouple signals and pyrometer signals. 
   
   
       15 . The control system of  claim 13 , wherein said control computer is further adapted to:
 receive data related to material properties of said MBE growth structure;   select temperature values based on said material properties of said MBE growth structure; and   send power signals to said heater to allow heating of said MBE growth structure based on the selected temperature values,   wherein crystals are grown on the heated MBE growth structure.   
   
   
       16 . The control system of  claim 15 , further comprising a thermocouple and a pyrometer adapted to monitor said MBE growth structure, wherein said control computer is further adapted to perform a thermocouple calibration sequence on said thermocouple and said pyrometer. 
   
   
       17 . The control system of  claim 15 , wherein said control computer is further adapted to set proportional integrating derivative (PID) control parameters to set a level of said output power signal. 
   
   
       18 . The control system of  claim 14 , further comprising a power supply unit, wherein said control computer is further adapted to:
 establish output power signal levels;   directly send said output power signal levels to said power supply unit; and   control temperatures in said MBE deposition process based on said output power signal levels.   
   
   
       19 . The control system of  claim 14 , wherein said MBE growth structure comprises a substrate wafer. 
   
   
       20 . The control system of  claim 15 , further comprising a thermocouple and a non-contact temperature monitor adapted to monitor said MBE growth structure, wherein said control computer is further adapted to perform a thermocouple calibration sequence on said thermocouple and said non-contact temperature monitor.