Hot viscous glass micromachining on wafer level enabling miniaturized high precision and low roughness concave mirrors for optical cavities

The hot viscous glass micromachining is one of the cornerstone modules in Silicon technology enabling the fabrication of glass based optical components on wafer-level. This technology allows the realization of spherical, aspherical, parabolic, ellipsoidal or dome-shaped glass elements with radii of curvature starting from smaller than 150 μm on wafer-level for application fields ranging from transparent hermetical sealings over concave ultra-smooth reflective surfaces in an ion-trap to micro-lens arrays. A technology platform for the glass micromachining will be shown in this paper. In addition to the description of the standard process flow, we introduce process simulations to determine and optimize process parameters and use them as guidelines for design rules to improve the component quality. Since the shape fidelity and surface roughness belong to the most relevant characteristics of a glass-based component, several examples for micro lenses and concave mirrors with very smooth surfaces of 0.6±0.2 nm roughness for an ion-trap and infrared applications will be discussed and reported.