Tuning of nanogap size in high tensile stress silicon nitride thin films

High tensile stress suspended structures are demanded for high mechanical quality factor applications. However, high tensile stress causes distortion of the original shapes by contracting, buckling, and bending the suspended structures. We demonstrate a method to compensate for the shape deformation of suspended structures due to intrinsic tensile stress after they are released. With a new design, the distance between two suspended structures after wet etch can easily be tuned by a single fabrication beyond the lithographic resolution limits. The technique is simulated by finite element analysis and experimentally implemented to demonstrate a gap tuning capability with 2.4 nm standard error.