In situ, non-destructive cvd surface monitor

Abstract

A non-intrusive, in-situ monitoring technique and apparatus is used for evaluating the presence and extent of a critical contaminating or passivating layer on a transparent sample, prior to a subsequent process step. A multiple internal reflection apparatus and method without the need for aligning mirrors reduces the time to maximize the light intensity through the sample and to the detector and eliminates the intensity loss due to reflection from each mirror. The technique and apparatus can be used to monitor for a critical hydrogen passivation layer so that it is maintained on the silicon surface right up to the point at which the reactants are introduced for the deposition. The in-situ monitoring and process control technique uses Fourier Transform Infrared Spectroscopy with Multiple Internal Reflections (FTIRS-MIR) which looks at the Si--H bond vibration. Apparatus implementing the technique provides a means of insuring reproducibility in films through direct monitoring of the passivating layer. The technique can be utilized in UHV Chemical Vapor Deposition (CVD) Low Pressure CVD (LPCVD), mid-pressure and atmospheric Chemical Vapor Deposition (CVD) systems. The technique provides a powerful experimental technique for correlating imposed experimental conditions with the presence or destruction of the passivation and the subsequent film quality obtained. The method is applicable to any portion of the electromagnetic spectrum for which the sample is transparent and internally reflecting with the absorption of energy at the sample's surface attributable to any species of interest that can be detected.