Finite element simulation of plane strain plastic-elastic indentation on single-crystal silicon

Meso-plasticity FEM technique was applied to simulate the dislocation generation and propagation during indentation of a single-crystal silicon. Dislocations were generated and concentrated under the indenter and propagated into the interior of the workmaterial as the indentation progresses. Similarly, the hydrostatic stress and the principal stress were concentrated directly underneath the indenter. The magnitudes of these stresses are found to increase with increase in the depth of indentation. It is proposed that pre-existing microcracks are not necessary for the defect generation in the workmaterial. Instead, a concentration of dislocations generated by plastic deformation under light loads and high hydrostatic pressures can play a similar role. The role of hydrostatic pressure in suppressing fracture was investigated. Based on these studies, it appears feasible to generate crack-free, smooth surfaces below a critical load or cut depth in ultraprecision machining of silicon. (C) 2000 Elsevier Science Ltd. All rights reserved.