Precision of noninvasive temperature measurement by diffuse reflectance spectroscopy

Abstract

Diffuse reflectance spectroscopy can be used as a noninvasive probe for measurement of temperature in real time. We have measured the precision of this technique to determine the temperature of Si and GaAs substrates during semiconductor processing. Our results show that the standard deviation of the noninvasive optical technique is less than 1.5 °C for GaAs and less than 2.0 °C for Si over the temperature range 25 °C<T<600 °C. This standard deviation compares favorably to that for a type-K thermocouple used in the same measurements: s.d.<1.5 °C. These results support the notion that noninvasive optical temperature measurement can be used in semiconductor processing with a precision approaching that of a thermocouple.

Real-Time Pseudodielectric Function of Low-Temperature-Grown GaAs

“…We actively controlled the substrate temperature during the growth by using a Thermionics DRS system supplying feedback to a commercial temperature controller [10,13,14]. The DRS system determines the substrate temperature by measuring the substrate absorption edge wavelength and comparing it to an empirical calibration table.…”

Real-time measurements of the pseudodielectric function of low-temperature-grown GaAs

“…14 We actively controlled the substrate temperature during the growth using a Thermionics DRS system supplying feedback to a commercial temperature controller. 12,15,16 The DRS system determines the substrate temperature by measuring the substrate absorption edge wavelength and comparing it to an empirical calibration table. This technique yields a demonstrated precision of better than 1°C and a measurement speed of better than 1 s. Figure 1 displays the DRScontrolled substrate temperature during the growth of four samples of LT-GaAs 100 nm thick at various growth temperatures.…”

Monitoring and Control in Vapor phase Epitaxy

“…Some of the technology areas where process control can be expected to have an important impact are: temperature measurement, flux measurement both for chemical composition and concentration, growth / etch rates, surface composition, and particle detection. [2][3] …”