A method for bonding at low or room temperature includes steps of surface cleaning and activation by cleaning or etching. The method may also include removing by-products of interface polymerization to prevent a reverse polymerization reaction to allow room temperature chemical bonding of materials such as silicon, silicon nitride and SiO.sub.2. The surfaces to be bonded are polished to a high degree of smoothness and planarity. VSE may use reactive ion etching or wet etching to slightly etch the surfaces being bonded. The surface roughness and planarity are not degraded and may be enhanced by the VSE process. The etched surfaces may be rinsed in solutions such as ammonium hydroxide or ammonium fluoride to promote the formation of desired bonding species on the surfaces.

An interposer including stress-engineered nonplanar microsprings may provide interconnection of bonding pads of electronic structures disposed above and below the interposer. The lateral offset between an anchor portion of a microspring disposed for contact at a bottom surface of the interposer and the tip of the microspring located in a free portion of the microspring for contact and deflection over a top surface of the interposer permits the interconnection of devices having different bonding pad pitches. Microspring contacts at the free portion permit temporary interconnection of devices, while solder applied over the free portion permit permanent connection of devices to the interposer.