Nanoscale quantitative stress mapping with atomic force microscopy

A nanometer scale noninvasive method for quantitatively mapping tensile strain in metals or semiconductors is demonstrated. The technique is based on the Kelvin probe force microscopy detection of changes in the electronic work function of a material resulting from the tensile strain. Measurements are quantified using a simple microlever mechanical system by recording changes in the work function as a function of the applied strain. A linear relationship of the work function on the tensile stress is observed with a stress sensitivity of 1kPa. Finally, the stress distribution in a strained silicon membrane is imaged.