Reliability of micromachined membranes under particle impact

We report experimental and numerical results on the mechanical reliability of silicon nitride membranes under particle impact. Over 1000 membranes of various geometries were subjected to controlled particle bombardment leading to their failure. Based on the statistical analysis of the characteristic times to failure /spl tau/ and their dependence on geometry, on the optical failure analysis, and on numerical simulations of impact events, the following conclusions are drawn: failure is due to a singular event as opposed to fatigue, failure is caused by impacts close to the membrane edge, the absolute distance of the impact point to the nearest edge is the dominant factor, the characteristic lifetime /spl tau/ is inversely proportional to the perimeter length, reinforcing the membrane perimeter secures an up to tenfold increase in lifetime.