Abstract:
A method and apparatus for measuring the concentration of a very small amount of impurities in an object gas by an infrared spectroscopic analysis using a semiconductor laser. In order to carry out the analysis with a high sensitivity and a high accuracy, an object gas is introduced into a sample cell (5) and the cell is evacuated by a vacuum pump (16). An infrared beam of a wavelength in a region in which a high absorption peak due to impurities appears is emitted from a semiconductor laser (1) and passed through the sample cell (5) and a reference sample cell (8) in which impurities alone are sealed to measure a differential value absorption spectrum. The impurities are identified by comparing the spectrum of the object gas with that of impurities alone and determining a plurality of absorption peaks concerning the impurities, and the quantity of the impurities is determined on the basis of the absorption intensity at the highest peak. When impurity gas molecules form clusters in the object gas, the light of not less than 0.5 eV is applied to the clusters to dissociate the same, and the analysis of the gas is then carried out. This invention is suitably utilized, especially, for analyzing a very small amount of impurities in a semiconductor material gas.
Abstract:
Provided is a novel chamber effluent monitoring system. The system comprises a chamber having an exhaust line connected thereto. The exhaust line includes a sample region, wherein substantially all of a chamber effluent also passes through the sample region. The system further comprises an absorption spectroscopy measurement system for detecting a gas phase molecular species. The measurement system comprises a light source and a main detector in optical communication with the sample region through one or more light transmissive window. The light source directs a light beam into the sample region through one of the one or more light transmissive window. The light beam passes through the sample region and exits the sample region through one of the one or more light transmissive window. The main detector responds to the light beam exiting the sample region. The system allows for in situ measurement of molecular gas impurities in a chamber effluent, and in particular, in the effluent from a semiconductor processing chamber. Particular applicability is found in semiconductor manufacturing process control and hazardous gas leak detection.
Abstract:
The selectivity, that is to say the ratio between the analyte-proportional signal and the foreign body-proportional signal is an essential factor in spectrometric measurements. When a narrow spectral band of the spectral domain is filtered by means of filter arrangements or the like and when supplying a detector of which the output signal is displayed, a sensitive improvement of the selectivity is obtained. The filter arrangement is periodically offset with respect to the spectral domain to be analyzed so that the spectral band passing through the filter arrangement is periodically offset through the spectral domain to be analyzed and the output signal from the detector is displayed through a lock-in amplifier of which the phase reference signal is proportional to the displacement.