Patent ID: 6962161

Claim:
A processing method for removing an unnecessary substance on a surface of a workpiece by bringing the surface of the workpiece into contact with supercritical carbon dioxide and additives in a pressurized processing chamber, said method comprising: sealing said processing chamber after loading said workpiece in said processing chamber; pressurizing said processing chamber with a first predetermined amount of pressurized carbon dioxide supplied to said processing chamber to a predetermined pressure and a predetermined temperature higher than a critical pressure and a critical temperature thereof respectively to form supercritical carbon dioxide in the processing chamber; dissolving said additives and a co-solvent in a second predetermined amount of the supercritical carbon dioxide by mixing said additives and said co-solvent with said supercritical carbon dioxide in an upstream portion of said processing chamber to form a pressurized fluid mixture thereof; removing an unnecessary substance on said workpiece while maintaining an interior pressure of said processing chamber higher than the critical pressure and the critical temperature of carbon dioxide, by supplying continuously a third predetermined amount of said pressurized fluid mixture to said processing chamber and removing from said processing chamber a substantially equal amount of a reacted pressurized fluid containing a dissolved amount of the unnecessary substance in the pressurized fluid mixture obtaining a first rinse fluid in which said co-solvent is dissolved in said supercritical carbon dioxide by stopping feed of said additives and mixing said co-solvent with said supercritical carbon dioxide in the upstream portion of said processing chamber; performing a first rinsing process for replacing the reacted pressurized fluid mixture in said processing chamber with said first rinse fluid while maintaining the interior pressure of said processing chamber higher than the critical pressure and the critical temperature of carbon dioxide, by supplying continuously said first rinse fluid to said processing chamber and removing from said processing chamber a substantially equal amount of the reacted pressurized fluid mixture to that of the first rinse fluid added; performing a second rinsing process for replacing said first rinse fluid in said processing chamber with said supercritical carbon dioxide as a second rinse fluid while maintaining the interior pressure of said processing chamber higher than the critical pressure and the critical temperature of carbon dioxide, by stopping supply of said co-solvent, supplying continuously only supercritical carbon dioxide to said processing chamber and removing from said processing chamber a substantially equal amount of the first rinse fluid to that of the supercritical carbon dioxide added; stopping feed of carbon dioxide to said processing chamber; decompressing said processing chamber to atmospheric pressure; and unloading said workpiece from said processing chamber.