Hardness measurement at penetration depths as small as 20 nm

TLDR

The study investigates indentation hardness at sub‑micrometre scales in nickel, gold, and silicon. Indentations with penetration depths down to 20 nm were performed, with indenter area measured by electron microscopy and penetration continuously monitored during loading and unloading. Hardness can be accurately derived from penetration depth, elastic relaxation is quantifiable, hardness rises sharply as indent size decreases, and silicon indents exhibit no cracking but display atypical deformation.

Abstract

Abstract In this paper we investigate the properties of indentation hardness on the sub-micrometre scale in nickel, gold and silicon. Indenter penetration depths as low as 20 nm are used. The area of the indents is determined by electron microscopy, and thus the Meyer hardness calculated. The indenter penetration is monitored continuously during loading and unloading. We show that indent areas, and therefore hardness, may be determined from penetration depth with reasonable accuracy, and that elastic relaxation can be quantitatively understood. We discuss the marked increase of indentation hardness with decreasing indent size on the sub-micrometre scale. Small indents in silicon showed no evidence of cracking, but did show unusual deformation characteristics.