| 摘要 |
PURPOSE:To raise the accuracy and stability of film thickness control by the procedure in which spectral permeability or spectral reflection factor on base plate is measured by at least more than 3 wave-length lights, and than a wave-length light with it max. value or min. value is obtained by mathmatical treatment for controlling the thickness of film. CONSTITUTION:The deposition base plate 13 is set on a holder fastened to the base 11 inside the bell jar 11. The signal light A is modulated to the chopper 32 by the light source 31 and parallel light is put in by the lens 33. On the other hand, the reference light B or a modulated light with phase 180 deg. different from the signal light A, is taken out of the lens 34 alternately with the signal light A. The signal light A reflected from the base plate 13 passes through the reference glass 20, and the reference light B is reflected at the reference glass 20. They alternately go into the high speed scanning spectrometer 40, where 9 points of the spectra of wave length 31 are selected by the spectral element 41 and the high frequency oscillator 52 to measure spectral reflection factor. They then enter the electronic computer 20 through the both digital and alalog signals treatment devices 51 and 60 and the photoelectronic amplifier 42, where a wave length with max. or min. value is obtained by a N-point comparison method for controlling the thickness of film, thus making the accuracy and stability of film thickness control higher. |
