Deep Etching of Silicon Based on Metal-Assisted Chemical Etching

A deep etching method for silicon microstructures was successfully developed.This wet etching process is based on metal-assisted chemical etching (MACE), which waspreviously mainly utilized to etch the features that have lateral dimensions ofnanometers.In thisnovel MACE, the critical improvement was to promote theout-of-planemass transfer at themetal/Si interface with an ultrathin metalfilm. This enabled us to etch micrometer-wide holes,which was previously challenging due to the mass transport limitation. In addition, it was foundthat when ethanol was used as a solvent instead of water, the formation of porous defects wassuppressed. Under the optimized etch conditions, deep (>200 mu m) and vertical (>88 degrees) holescould be carved out at a fast etch rate (>0.4 mu m/min). This novel deep MACE willfind utility inapplications such as microelectromechanical systems (MEMS) devices or biosensors

Automated summary

This research successfully developed a deep etching method for silicon microstructures using metal-assisted chemical etching technology, achieving fast etching of deep and vertical holes with high precision under the action of ultra-thin metal film, and avoiding the formation of porous defects.