XeF2 etchining system is designed to expose samples to xenon difluoride gas (XeF2) in a cyclic mode in which the etch chamber is repeatedly filled with XeF2 gas and pumped out again. The main advantage of XeF2 etching system in comparism to other silicon etchants is in high selectivity to silicon with respect to aluminum, photoresist, and silicon dioxide. Since this technique etch silicon isotropic, large structures can be undercut.