Apparatus and method for controlling heating of base within chemical vapour deposition chamber
Provided are an apparatus and a method for controlling the heating of the base within a chemical vapour deposition chamber, which apparatus is applicable to an MOCVD reaction chamber. The apparatus comprises a heater located within a chamber; a tray located near the heater within the chamber and spaced apart from the heater and used for carrying the base; a first temperature control unit coupled with a surface of the tray for carrying the base and used for measuring the temperature of the tray surface and outputting a first control signal as a function of a set temperature and the temperature of the tray surface; and a second temperature control unit connected to the first temperature control unit and used for measuring the temperature of the middle of the area between the tray and the heater, and also for outputting a second control signal as a function of the first control signal and the temperature of the middle, with the heater being coupled with the second temperature control unit to heat according to the second control signal. Further provided is a method for controlling the heating of the base within a chemical vapour deposition chamber. A steady base temperature can be obtained via the apparatus.
1. An apparatus for controlling heating of a substrate in a chemical vapor deposition chamber, comprising:
a heater located in the chamber;
a tray located near the heater and spaced apart from the heater in the chamber, and configured to support the substrate;
a first temperature control unit, coupled with a first temperature measurer, the first temperature measurer configured to measure a first actual temperature of a surface of the tray, the first temperature control unit configured to generate a first control signal based on a set temperature value and the first actual temperature of the surface of the tray and convert the first control signal into a set intermediate temperature; and
a second temperature control unit, connected to the first temperature control unit and to a second temperature measurer, the second temperature measurer configured to measure a second actual temperature of an area between the tray and the heater, the second temperature control unit configured to output a second control signal based on the set intermediate temperature and the second actual temperature,
wherein the heater is coupled with the second temperature control unit and configured to heat based on the second control signal.
2. The apparatus according to claim 1 , wherein a time constant of the second temperature control unit is less than a time constant of the first temperature control unit.
3. The apparatus according to claim 1 , wherein a ratio of a time constant of the first temperature control unit to a time constant of the second temperature control unit is in a range from 1 to 25.
4. The apparatus according to claim 1 , wherein
the first temperature control unit comprises a first temperature setter, a first temperature controller and a signal converter, wherein
the first temperature measurer is connected with a first input terminal of the first temperature controller and is configured to measure the first actual temperature of the surface of the tray and send the first actual temperature to the first temperature controller;
the first temperature setter is connected with a second input terminal of the first temperature controller and is configured to provide the set temperature value to the first temperature controller;
the first temperature controller is configured to compare the first actual temperature with the set temperature value and output the first control signal based on a difference between the first actual temperature and the set temperature value; and
the signal converter is connected with an output terminal of the first temperature controller and is configured to receive the first control signal, convert the first control signal into the set intermediate temperature and send the set intermediate temperature to the second temperature control unit.
5. The apparatus according to claim 4 , the signal converter is provided with a linear relationship or a non-linear relationship between the first control signal and the set intermediate temperature, and the signal converter is configured to receive the first control signal, convert the first control signal into the set intermediate temperature corresponding to the first control signal and send the set intermediate temperature to the second temperature control unit.
6. The apparatus according to claim 4 , wherein the second temperature control unit comprises a second temperature controller,
the second temperature measurer is located between the tray and the heater and connected with the second temperature controller, and is configured to measure the second actual temperature of a measuring point between the tray and the heater and send the second actual temperature to the second temperature controller; and
the second temperature controller is connected with the signal converter, and is configured to compare the second actual temperature with the set intermediate temperature and output the second control signal based on a difference between the second actual temperature and the set intermediate temperature.
7. The apparatus according to claim 6 , wherein the apparatus further comprises a driving power supply connected with the second temperature controller and the heater, and the driving power supply is configured to receive the second control signal, supply a heater current based on the second control signal and input the heater current to the heater.
8. The apparatus according to claim 4 , wherein the first temperature measurer is an optical temperature measurement instrument based on multi-wavelength.
9. The apparatus according to claim 6 , wherein the second temperature measurer is a thermocouple.
10. The apparatus according to claim 6 , wherein the second temperature measurer is located at a position which is between the tray and the heater and closer to the heater.
11. The apparatus according to claim 6 , wherein the second temperature measurer and a heat radiating surface of the heater are in a same plane.
12. The apparatus according to claim 6 , wherein a bottom of the chamber is provided with an gas outlet configured to exhaust gas, and the second temperature measurer is located near the gas outlet.
13. The apparatus according to claim 6 , wherein the second temperature controller is a temperature controller with a P mode.