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Abstract

A process for removing two or more contaminants from a substrate in a single process. The substrate to be cleaned is contacted with a dense phase gas at or above the critical pressure thereof. The phase of the dense phase gas is then shifted between the liquid state and the supercritical state by varying the temperature of the dense fluid in a series of steps between temperatures above and below the critical temperature of the dense fluid. After completion of each step in the temperature change, the temperature is maintained for a predetermined period of time in order to allow contact with the substrate and contaminants and removal of the contaminants. At each step in the temperature change, the dense phase gas possesses different cohesive energy density or solubility properties. Thus, this phase shifting of the dense fluid provides removal of a variety of contaminants from the substrate without the necessity of utilizing different solvents. In alternative embodiments, ultraviolet radiation, ultrasonic energy, or reactive dense phase gas or additives may additionally be used.

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First Claim