TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The amount of fluid modifier ranges between 0-30%, preferably 0.5-10% of the total volume of the mixture.Preferred Process: The supercritical composition contacts the substrate at 0-300 degreesC and at a pressure of 500-10500 psi and then, at 0-300 degreesC and at a pressure of 550-10500 psi sequentially. The temperature and pressure during the first and second processes are preferably 50-100 degreesC, 500-10500 psi and 50-100 degreesC, 2000-4000 psi, respectively. The first and second processes are repeated until the photoresist material is completely removed from the substrate. Preferred Definitions: Fluid modifier has formula (III) or (IV)    R1,R2,R3 and R4 = H, 1-10C (halogenated) hydrocarbons, halogens.    SPECIFIC COMPOUNDS - The phase fluid modifier is chosen from propylene carbonate (4-methyl-1,3-dioxalane-2-one), ethylene carbonate, butyl carbonate, dimethyl sulfoxide or gamma-butyrolacetone (2,4-dioxalane-3-one). The dense phase fluid is chosen from carbon dioxide, argon, helium, nitrogen, methane, ethane, propane or butane.    EXAMPLE - 95% of carbon dioxide and 5% of propylene carbonate mixture was used as feed material and introduced into a reservoir. The reservoir was connected to ballast tank and cleaning vessel through pipes and were maintained at 50 degreesC and 900 psi for 2 minutes. The ballast tank was pressurized to 1600 psi. Due to the pressure difference in the ballast tank and cleaning vessel, the mixture was sprayed onto the wafers with high pressure and velocity, thus removing photoresist from the wafers. The pressure in the cleaning vessel and ballast tank was allowed to equilibrate and dropped to 1100 psi. The ballast tank was repressurized to repeat the same procedure for 3 times. After 30 minutes static and 30 minutes dynamic contact with the mixture, the resist was removed easily. The silicon wafer was then removed from the cleaning vessel and rinsed with deionized and filtered water. The silicon wafer was analyzed and found that the photoresist material was completely removed. The pressure and/or temperature and concentration of propylene carbonate were varied, and the process was repeated. The process at low temperature and pressure was unsuccessful.