Controlled stress-induced shaping of molybdenum microstructures

A reliable fabrication process for passive, monolithic microstructures is described. It is shown that by using pressure as a variable during physical vapour deposition (PVD), the stress in the deposited films can be controlled. A built-in stress gradient obtained by depositing the structural layer at different pressures results in a relatively predictable outof- plane deflection of the structure after release. Sacrificial aluminum underneath molybdenum structures was found to be the most reliable combination of materials. Thermal stress fracturing at the hinges of the cantilever structures was reduced by altering the deposition process.