Chamber Radiation Effects on Calibration of Radiation Thermometers With a Thin-Film Thermocouple Test Wafer

Published

June 1, 1999

Author(s)

Benjamin K. Tsai, D P. DeWitt, Francis J. Lovas, Kenneth G. Kreider, Christopher W. Meyer, David W. Allen

Abstract

In the semiconductor industry, Rapid Thermal Processing (RTP) utilizes a prescribed temperature-time recipe to silicon wafers undergoing processes such as annealing and oxide film formation. The National Technology Roadmap for Semiconductors (NTRS) requirement is to measure wafer temperatures with an uncertainty of1 K and reproducibility of 0.25K in the range from 800 K to 1300 K. (All uncertainties in this document correspond to a coverage factor of one or k=1, unless otherwise specified.) The purpose of our study is to demonstrate a methodology for using light-pipe radiation thermometers (LPRTs) for determination of temperatures in RTP chambers traceable to the International Temperature Scale of 1990 (ITS-90) [2] with the prescribed uncertainty. Spectral radiance temperatures, Tδ, are observed with an LPRT on a silicon wafer instrumented with wire-thermocouples and calibrated thin-film thermocouples (TFTCs). To determine the true temperature, the effective emissivity of the wafer must be estimated, accounting for wafer emissivity variability and RTP chamber radiation characteristics including surface geometries and radiative properties. Based upon five-region multizone classical diffuse/specular enclosure models the diffferences between the thermocouple temperature measurements and the corrected LPRT temperature are less than 3.5 K for a wafer-shield gap separation of 12.5 mm. The major contributions to this difference are the limitations of the enclosure model and the temperature gradient in the vicinity on the LPRT target area.

Proceedings Title

Proceedings of the Symposium on Temperature and Thermal Measurement in Industry and Science (TEMPMEKO '99)

Conference Dates

June 1-3, 1999

Conference Location

Delft, NL

Conference Title

Symposium on Temperature and Thermal Measurement in Industry and Science

Pub Type

Conferences

Keywords

accuracy, effective emissivity, enclosures, light pipe radiometer, modeling, rapid thermal processing, temperature, thin-film thermocouple, uncertainty

Citation

Tsai, B. , DeWitt, D. , Lovas, F. , Kreider, K. , Meyer, C. and Allen, D. (1999), Chamber Radiation Effects on Calibration of Radiation Thermometers With a Thin-Film Thermocouple Test Wafer, Proceedings of the Symposium on Temperature and Thermal Measurement in Industry and Science (TEMPMEKO '99), Delft, NL (Accessed December 15, 2024)