Simulation Results of Uniaxial Micromirrors with Conic-Backside and V-Arm Flexures for Scanner and Display Applications

Performance simulations of uniaxial micromirrors with 1)conic backside to enhance flatness and 2)V-shaped suspension arms to reduce torsional stress and suppress unwanted sideways resonance modes are presented in this paper. Initial results indicate that circular and rounded-rectangular micromirrors with the V-arm flexures can resonate at 16.7 kHz and 3.2 kHz, respectively. Dynamic mirror warpages of about 100 nm is in accordance with the λ/4 criteria for visible light. At ±30° mirror deflections, besides having rounded junctions, the length and width of the flexures are adjusted such that the maximum stress is only about 1/3 the fracture strength of silicon. As the resonances are excited externally, and also with the acceptable reflectivity of silicon under the visible spectrum, the conductive wiring patterns and the reflective metal layer can both be omitted. In addition, since a single photomask can realize conic mirror backside, the microfabrication cost can be further reduced. We are confident that an assembly of these two uniaxial micromirrors on a 3D optical bench can generate high precision yet economical 2D microscanners for display applications.