System and process for calibrating pyrometers in thermal processing chambers
View Patent ↗A method and system for calibrating temperature measurement devices, such as pyrometers, in thermal processing chambers are disclosed. According to the present invention, the system includes a calibrating light source that emits light energy onto a substrate contained in the thermal processing chamber. A light detector then detects the amount of light that is being transmitted through the substrate. The amount of detected light energy is then used to calibrate a temperature measurement device that is used in the system.
1. A system, comprising:
a chamber adapted to receive at least one semiconductor wafer;
a lamp heat source in communication with said chamber;
a first temperature measuring device configured to detect radiation thermally emitted from a first location on the semiconductor wafer, the first location being positioned at a first radial distance from the center of the semiconductor wafer; and
a second temperature measuring device configured to determine the temperature of the semiconductor wafer based on a temperature dependence of an optical property of the semiconductor wafer, the second temperature measuring device comprising at least one light source that radiates light energy onto a second location on the semiconductor wafer, the at least one light source configured to be controlled independently of the lamp heat source, the second temperature measuring device further comprising at least one light detector positioned to detect the light energy from the light source after the light energy has been transmitted through or reflected from the semiconductor wafer;
wherein the second location is located at a second radial distance from the center of the semiconductor wafer, the difference between the first radial distance and the second radial distance being no greater than about 5 cm.
2. The system of claim 1 , wherein the difference between the first radial distance and the second radial distance is no greater than about 4 mm.
3. The system of claim 1 , wherein the first location and the second location are separated by a linear distance that is no greater than about 5 cm.
4. The system of claim 1 , wherein the first location and the second location are separated by a linear distance that is no greater than about 4 mm.
5. The system of claim 1 , wherein the semiconductor wafer has a thermal diffusion length, the first location and the second location being separated by a linear distance no greater than about three times the thermal diffusion length of the semiconductor wafer at a wafer temperature of 700° C.
6. The system of claim 1 , wherein the system further comprises a substrate holder configured to rotate the semiconductor wafer.
7. The system of claim 1 , wherein the system further comprises a controller in communication with said first temperature measuring device and said second temperature measuring device, said controller being configured to receive information from said second temperature measuring device and to use the information to calibrate said first temperature measuring device.
8. The system of claim 1 , wherein the system further comprises a controller in communication with said second temperature measuring device, said controller configured to use information received from said second temperature measuring device to determine the temperature of the semiconductor wafer at wafer temperatures less than 800° C.
9. The system of claim 1 , wherein the at least one light source of the second temperature measuring device radiates light energy at least a first wavelength and a second wavelength, the at least one light detector of said second temperature measurement device being configured to detect light energy at least the first wavelength and the second wavelength.
10. The system of claim 1 , wherein said first temperature measuring device comprises a pyrometer.
11. The system of claim 1 , wherein said at least one light detector comprises a photosensor.
12. The system of claim 1 , wherein said at least one light detector is configured to detect light energy comprising electromagnetic radiation at a wavelength from about 1 micron to about 2 microns.
13. The system of claim 1 , wherein said at least one light source comprises a laser, a light emitting diode, a super-luminescent light emitting diode, or a super-fluorescent fiber laser.
14. The system of claim 5 , wherein the linear distance is no greater than the thermal diffusion length of the semiconductor wafer at a wafer temperature of 700° C.
15. The system of claim 6 , wherein the difference between the first radial distance and the second radial distance is no greater than about 4 mm.
16. The system of claim 6 , wherein the difference between the first radial distance and the second radial distance is no greater than about three times the thermal diffusion length of the semiconductor wafer at a wafer temperature of 700° C.
17. The system of claim 6 , wherein the difference between the first radial distance and the second radial distance is no greater than the thermal diffusion length of the semiconductor wafer at a wafer temperature of 700° C.
18. The system of claim 9 , wherein said at least one light source comprises a first light source and a second light source, said first light source radiating light energy at the first wavelength and said second light source radiating light energy at the second wavelength.
19. The system of claim 9 , wherein said at least one light detector comprises a first light detector and a second light detector, said first light detector configured to detect light energy at the first wavelength and said second light detector configured to detect light energy at the second wavelength.
20. The system of claim 9 , wherein said system further comprises a controller in communication with said second temperature measuring device, said controller configured to determine a relative transmission based at least in part on the light energy detected at least the first wavelength and the second wavelength.
21. The system of claim 20 , wherein said controller is configured to determine a wafer temperature of the semiconductor wafer based at least in part on the relative transmission.
22. The system of claim 21 , wherein said controller is configured to control said lamp heat source based on the determined wafer temperature at wafer temperatures of less than about 800° C.