Laser-Based Optical Scattering Detection of Surface and Subsurface Defects in Machined Si3N4 Components

Abstract

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Methods for Detection of Subsurface Damage: A Review

“…Therefore, only the light reflected from the focal point in the sample goes through the detection pinhole and is then received. The confocal microscopy provides higher resolution detection compared to the traditional microscopy, and has been applied to detecting SSD in ceramics [15,82], optical parts [83] and semiconductor materials [5].…”

“…The Argonne National Laboratory and the Kansas State University jointly developed the cross-polarization confocal microscopy (CPCM) to measure SSD in the ground ceramics and silicon wafers [5,15,[85][86][87][88][89][90][91][92]. As shown in Figure 8, an incident light is linearly polarized and hits the surface of a sample.…”

“…Hard and brittle materials are widely used because of their excellent physical and mechanical properties, such as high hardness and strength at elevated temperatures, wear and corrosion resistances, etc. Among hard and brittle materials, single crystalline silicon is the predominant substrate material for integrated circuits (IC) [1][2][3][4][5]; optical glasses are for optical windows and lens [6][7][8][9][10][11] as well as high-power laser components [12]; ceramic materials are commonly used for bearings, cutting tools and machine parts [13][14][15][16]. However, these materials are also difficult to machine due to their hard and brittle nature.…”

Impact of Dislocation on Warpage of Thinned 4H-SiC Wafers

“…The corresponding morphology in section, investigated by TEM analysis (images not shown), reveals a damaged region with lateral and median cracks extending for a depth of about 600 nm. This damaged region is an area with high density dislocations and large strain [8,9]. Despite the same grinding process has been performed on all SiC wafers under investigation, different Cbow values have been measured as it is possible to see from data collected in fig.…”

Image Acquisition and Segmentation for Ceramic Bearing Ball Surface Inspection System

“…Laser scatter technology is a high precision method used to detect ceramic defects as small as 10μm. But only specimens with artificial cracks and subsurface cracks were detected [8,9].…”