A novel method for measuring the strength of microbeams

A novel method and test structure for measuring the strength of brittle microbeams is presented. The method does not require any measurement of forces or displacements. The test structure includes a microbeam that is wrapped over a curved side-wall by application of an unmeasured force. With the progression of wrapping, increasing tensile stresses are induced in the microbeam. When sufficiently high stresses are induced, the beam breaks. The failure stress is deduced by measuring the length of the remaining ligament of the broken beam. The method is demonstrated by measuring the strength of microbeams in bulk-micromachined test structures.