How does supercritical drying work?

From what I understand, you pressurise a gas so it becomes liquid. Then use it for whatever you want to use it inside the pressurised vessel and after you finish you reduce the pressure in the vessel, which causes the liquid to change back to gas and evaporate.

 

At least that's how it's used in supercritical extraction of essential oils by liquid carbon dioxide. Liquid CO2 is very good solvent for essential oils, very expensive procedure though.

in the super critical regime there is no difference between a liquid and a gas. they are no longer seperate phases.

The wikipedia article does a good job of explaining. If you need something clarified, feel free to ask.

 

http://en.wikipedia.org/wiki/Supercritical_drying

At high enough pressure and temperature, there it acts like both a liquid and a gas. A cool application is in making aerogels, in which case supercritical drying is vital so that the gel is not crushed by surface tension. Aerogels are fairly strong for their weight, and about as light as air.

Supercritical resist drying allows the fabrication of high aspect-ratio (AR) resist patterns. The potential of this drying technique to increase the maximum achievable AR and the resolution of the overall lithographic process is analyzed for Hydrogen SilsesQuioxane (HSQ). The maximum achievable AR is doubled compared to conventional nitrogen blow drying. Furthermore, the resolution is improved significantly.