Temperature diagnostics for a dual-arc FRTP tool

Vortek´s new 300 mm flash-assist RTP™ tool uses a pair of arc lamps to heat wafers at >200°C/s to an intermediate temperature of between 700°C and 1200°C. A high power, millisecond duration flash is then applied to the device side of the wafer, raising it to a higher peak temperature. Water-cooled windows and the cooling walls of the arcs attenuate incident radiation at the diagnostic wavelength of 1450 nm. This facilitates measuring the temperature of both wafer surfaces during the entire thermal process. A fast radiometer, which samples the back surface of the wafer at 25 kHz, provides feedback to a 1 kHz arc control system. An emissometer measures the back-surface emissivity, while one of its components, a near-infrared camera, provides a two-dimensional map of wafer temperature. An ultra-fast radiometer, which samples at up to 1 MHz, measures the device side of the wafer and estimates the peak temperature of the wafer during the flash. This radiometer has dynamic re-calibration and temperature-compensated electronics. All detectors are InGaAs. The fast radiometer, the ultra-fast radiometer, and the camera have effective resolutions of 16, 14, and 11 bits respectively. The individual components of the temperature measurement system are described. The methodologies used to achieve intermediate temperature control of better than ±2°C and emissometer stability of ±0.2% are discussed.