 Supercritical Fluid Wafer Cleaning System
 The complexity of integrated circuits has been increasing as lithography technology improves. In order to achieve pattern widths in the sub-micrometer range, the method of photoresist stripping and cleaning of silicon wafers is critical. Supercritical CO2 offers excellent performance as a cleaning solvent in the photoresist stripping/cleaning/drying processes due to unique properties such as low viscosity, high diffusivity, high permeability, no surface tension, among other reasons.
In addition, the fluid becomes a gas when reducing the pressure to atmospheric at ambient temperature. A liquid solvent can often collapse microstructures with a high aspect ratio due to its high surface tension. On the other hand, supercritical CO2 has no liquid-gas phase boundary and no surface tension occurs, therefore, the fluid can penetrate into microstructures without damaging the lithography pattern.
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