An average diffraction intensity ratio (y=(h.sub.1, k.sub.1, l.sub.1)/(h.sub.2, k.sub.2, l.sub.2)) for a rotation angle () is obtained from a first diffraction chart and a second diffraction chart, and a surface temperature during deposition is calculated based on this average diffraction intensity ratio. Based on data on the surface temperature of a polycrystalline silicon rod calculated and supplied current and applied voltage during the deposition of the polycrystalline silicon rod, the supplied current and the applied voltage when newly manufacturing a polycrystalline silicon rod is controlled to control a surface temperature during the deposition process. By using such a temperature control method, it is also possible to control the difference T (=T.sub.cT.sub.s) between the center temperature T.sub.c and the surface temperature T.sub.s of a polycrystalline silicon rod during a deposition process to control the value of residual stress in the polycrystalline silicon rod.

A method can include collecting time traces for N calibration instances of a device and identifying a key feature for the device based on the time traces. The method can also include using an equation to determine a key feature variation based on a predicted value and a measured value for each new qualified instance of the device. The method can also include generating an alert based on the key feature variation.

The present invention provides a multi-wavelength spectral thermometry based on mobile narrow-band window and optimization and belongs to the field of thermal radiation temperature detection. A continuous spectrum of a thermal radiation object is collected by a spectrometer; the spectrum of the thermal radiation object is denoised, windowed and standardized; the whole detection wavelength range is traversed within an appropriate narrow-band window; through comparison with windowed and standardized black-body radiation spectra at different temperatures in a corresponding spectral window, the temperature and emissivity distribution of the thermal radiation object is calculated with high accuracy without depending on emissivity model estimation, and high universality and noise resistance are achieved.

A method of stabilizing temperature sensing in presence of temperature-sensing component temperature variation includes steps of: obtaining response value caused by black body at first temperature of a thermal imager core chip; obtaining high-temperature first-order linear function of high-temperature black body response value versus thermal imager core chip temperature; obtaining low-temperature first-order linear function of low-temperature black body response value versus thermal imager core chip temperature; obtaining response value of high-temperature first-order linear function at first temperature, response value of high-temperature first-order linear function at second temperature of the thermal imager core chip, response value of low-temperature first-order linear function at first temperature, response value of low-temperature first-order linear function at second temperature, and response value of black body and substituting the five values into an equation for correcting the response values; and obtaining instant corrected value of the response value of the black body.

A method of stabilizing temperature sensing in presence of temperature-sensing component temperature variation includes steps of: obtaining response value caused by black body at first temperature of a thermal imager core chip; obtaining high-temperature first-order linear function of high-temperature black body response value versus thermal imager core chip temperature; obtaining low-temperature first-order linear function of low-temperature black body response value versus thermal imager core chip temperature; obtaining response value of high-temperature first-order linear function at first temperature, response value of high-temperature first-order linear function at second temperature of the thermal imager core chip, response value of low-temperature first-order linear function at first temperature, response value of low-temperature first-order linear function at second temperature, and response value of black body and substituting the five values into an equation for correcting the response values; and obtaining instant corrected value of the response value of the black body.