Crystal Defect Analysis of Latent Scratch Induced during CMP Process on 4H-SiC Wafer Using Electron Microscopy
The dislocation analysis of latent scratch induced chemical mechanical polishing process on 4H-silicon carbide (SiC) using the multi directional scanning transmission electron microscopy (STEM) method and elastic stain measurement were performed. A scanning electron microscope image shows that a latent scratch extended toward the  direction and the width is about 50 nm. Cross sectional STEM images shows that the depth of latent scratch due to distortion is about 20 nm. From the result of plan view STEM observation along  direction, it was observed that a latent scratch had two defect lines toward the  direction, which were a loop type on upper side and a linear type on the lower side. The Burgers vector of each defect have a component in basal plane. Elastic strain mapping was performed using transmission electron microscope equipped with a procession diffraction system. Inside the latent scratch indicates stain-free field, however around latent scratch indicates compressive strain field. About 1.5 % compressive strain field x, y direction and shear strain along latent scratch exists on typical area. As a results of STEM and elastic strain analysis, the atomic arrangement in basal plane seems to be related with the compressive strain around latent scratch.
Robert Stahlbush, Philip Neudeck, Anup Bhalla, Robert P. Devaty, Michael Dudley and Aivars Lelis
T. Sato et al., "Crystal Defect Analysis of Latent Scratch Induced during CMP Process on 4H-SiC Wafer Using Electron Microscopy", Materials Science Forum, Vol. 924, pp. 531-534, 2018