a-Si Pinhole Detection and Characterization using Haze Monitoring : CFM: Contamination Free Manufacturing

This paper describes a novel methodology for identifying pinholes (defects in thin films) in an amorphous silicon (a-Si) film using a KLA Surfscan® SP5 laser scattering-based unpatterned wafer inspection system. Inherent to the deposition mechanism, pinholes exist at the interface between a-Si/substrate. It is crucial to find the optimized film thickness that is free of pinholes. In this study we developed a unique process monitoring method adapted to quantify pinhole defects using surface haze. Haze is the background scattering signal of the wafer obtained from the inspection system [1] and the defect signal from scanning electron microscope (SEM) images from an eDR® e-beam defect review system. A macro program was developed to automatically process the SEM images and quantify the defect signal. A strong correlation between haze and a-Si pinhole count was observed. The method can be extended to different films including SiN, TiN and similar scenarios, where unconventional defect detection methods are needed.