Microlens Array Fabrication by Chemical Mechanical Polishing

Chemical mechanical polishing (CMP) was used to shape hexagonally arranged 20 μ m diam cone-shaped structures, prepared by wet etching of Corning 2496 glass, into microlenses. Edge rounding, which occurs during CMP due to a higher removal rate at the edges, was utilized for shaping of the microlenses. Microlenses with an H ∕ D ratio of ∼ 1 ∕ 10 and radius of curvature of 27.5 μ m were obtained. CMP variables that affect the contact pressure and material removal rate are downpressure, linear velocity, slurry, and properties of the pad. These variables being external to substrate provide great flexibility and, hence, suitability of the process for a wide range of materials.