High temperature micro-glassblowing process demonstrated on fused quartz and ULE TSG

We report, for the first time, a MEMS fabrication process for building atomically smooth, symmetric 3-D wineglass and spherical shell structures, using low internal loss materials, namely fused quartz and ultra low expansion titania silicate glass (ULE TSG). The approach consists of three major steps: (1) a deep fused quartz cavity etch, (2) plasma activated bonding of fused quartz to fused quartz or TSG and (3) a high temperature (up to 1700 °C) micro-glassblowing process. An in-house process capability of 1800 °C glassblowing with a rapid cooling rate of 500 °C/min was developed. Feasibility of the process has been demonstrated by fabrication of fused quartz and TSG micro-glassblown structures. Spherical and inverted-wineglass shells with self-aligned stem structures were fabricated using this process. The approach may enable new classes of TSG and fused quartz MEMS devices with extremely low surface roughness (0.23 nm surface average), intrinsically low thermoelastic dissipation (QTED > 5E+10), and highly symmetric structures (radial error < 500 ppm).