Stress-induced curvature of focused ion beam fabricated microcantilevers

Microcantilevers with very low spring constants, as required to measure the short-range Casimir force, can be fabricated by focused ion beam thinning of conventional atomic force microscope cantilevers, but the resulting beams have a stress-induced curvature. This can be explained by consideration of the implanted gallium ions and associated damage effects in the etched surface. The problem can be overcome by using a complementary etch method in which top and bottom surfaces of the microcantilever are etched by the same amount.