Abstract: One inventive aspect relates to a method for forming hermetically sealed cavities, e.g. semiconductor cavities comprising fragile devices, MEMS or NEMS devices. The method allows forming hermetically sealed cavities at a controlled atmosphere and pressure and at low temperatures, for example, at temperatures not exceeding about 200° C. The method further allows forming sealed cavities with short release times, for example, release times of about a few minutes to 30 minutes. The method may, for example, be used for zero level packaging of MEMS or NEMS devices.