Supercritical point drying apparatus for semiconductor device manufacturing and bio-medical sample processing

Abstract

A critical point drying apparatus for sample preparation in electron microscopy and semiconductor wafer production includes a computer system to automate the operational modes in drying the specimen. These operational modes controlled by the computer system are: cooling, in which a drying chamber is cooled; starting, in which the specimen chamber is filled with a transitional fluid; purging, in which the transitional fluid purges an intermediary fluid from the drying chamber and the purged intermediary fluid is collected by a collector condenser; heating, in which the drying chamber is heated to elevate the transitional fluid to its critical point temperature and pressure; and bleeding, in which the drying chamber is depressurized to atmospheric pressure at a very slow rate until the drying chamber is completely vented, which signals the end of the drying operation. The drying chamber incorporates concave surfaces for pressure dispersal and to facilitate purging the intermediary fluid completely. The drying chamber incorporates angled inlet ports and windows that are sealed with gaskets. The drying chamber also incorporates the usage of a wafer holder, spacer rings and inserts to allow for the secure suspension of wafers being processed. Passing the cooling fluid through a closed loop refrigeration system may also cool the drying chamber.