The supercritical fluid is highly diffusible and resolvable without the attraction due to surface tension. Through the use of supercritical drying, it is possible to dry delicate materials whilst maintaining their structure, whereas conventional drying methods cause extensive deformation and deterioration in structure. Carbon dioxide is often used as the supercritical fluid. This is because that it is possible to take out a dried-sample from cleaning liquid since the supercritical carbon dioxide can resolve various materials and vaporizes below the critical point. It is used for the drying process without stiction in MEMS device fabrication..