In-situ-spectroscopic monitoring for SiC-CVD process control

The objectives of this contribution are the integration of a FTIR spectrometer onto a waste gas line of a SiC-CVD demonstrator unit and the correlation of the measured gas phase spectra with formation of polychlorosilane deposits. The formation of polychlorosilanes during low pressure CVD processes of SiC is the most limiting factor in scaling up of CVD units. Therefore, it is absolutely necessary to monitor and to control this waste gas process. It is shown that FTIR measurements can be applied to solve such a problem. The paper is subdivided in the following three parts. First, the optical and mechanical adaption of the FTIR equipment are shown; second, FTIR measurements in the SiC-CVD demonstrator and interpretation of the measured spectra are presented; and third, the opportunities for process control are discussed.