Material removal mechanisms of monocrystalline silicon under the impact of high velocity micro-particles

Abrasive jet micromachining is a novel non-conventional machining process with applications in the opto-electrical and semiconductor industries. To understand the process, it is important to investigate the material removal mechanisms starting from a single particle impact. Different types of impressions or erosions produced by single particle impact on monocrystalline silicon and the effect of erosion parameters are presented and discussed. It is found that particle velocity, particle size and erosion angle all play an important role in the material removal process. Three types of impressions are broadly identified which include craters, scratches and microdents. Among these types of impressions, craters with brittle cleavage fractures cause instant material removal by crushing upon micro-particle impact. On the other hand, scratches are mainly responsible for crack network formation, which decreases material strength. The radial and lateral crack networks, which cause material spalling, are present in both surface and sub-surface region as shown by electron microscopy investigation. A transmission electron microscopy study shows the retention of crystalline structure below the crater impressions. It is also found that increasing the particle velocity, particle size and erosion angle increases the formation of crater-type impressions.