On-Chip High-Voltage Charge Pump With MEMS Post-Processed Standard 5-V CMOS on SOI for Electroosmotic Flow Micropumps

A novel on-chip integrated high-voltage (HV) generator is realized by our unique MEMS post-processing method with the standard CMOS process on a silicon-on-insulator (SOI). Foundry-made charge-pump elements with standard 5-V transistors on an SOI are isolated with deep reactive ion etching and isotropic etching. This method facilitated the successful operation of a HV-requiring MEMS device, the nominal working voltage of which is greater than 50 V, and by using the silicon device, the driving of an electroosmotic flow micropump was demonstrated. The measured output was proportional to the number of pump stages, and it was observed as 95.2 V with 20 stages. The post-processed CMOS-on-SOI can sustain voltages up to 800 V, and various MEMS with very high voltages can be driven using this technology.