Scanning and transmission electron microcopies of single-crystal silicon microworn/machined using atomic force microscopy

Atomic force microscopy (AFM) is commonly used for microwear/machining studies of materials at very light loads. To understand material removal mechanism on the microscale, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies were conducted on the microworn/machined single-crystal silicon. SEM studies of micromachined single-crystal silicon indicate that at light loads material is removed by ploughing. Fine particulate debris is observed at light loads. At higher loads, cutting type and ribbon-like debris were observed. This debris is loose and can be easily removed by scanning with an AFM tip. TEM images of a wear mark generated at 40 mu N show bend contours in and around the wear mark, suggesting that there are residual stresses. Dislocations, cracks, or any special features were not observed inside or outside wear marks using plan-view TEM. Therefore, material is mostly removed in a brittle manner or by chipping without major dislocation activity: crack formation, and phase transformation at the surface. However, presence of ribbon-like debris suggests some plastic deformation as well.