Compressed fluid technology: Application to RIE‐developed resists

A novel plasma‐developed resist lithographic process is described that uses compressed CO2 to extract nonvolatile siloxane molecules from host organic polymers. The process is capable of at least 0.75 μm resolution with an X‐ray sensitive guest siloxane‐host polymer system. A processing window was investigated and defined to eliminate or minimize film damage during compressed fluid extraction. Polymer deformation was usually avoided by using supercritical CO2 rather than liquid CO2, provided that film thicknesses were ≤1 μm. Increased solute concentrations in the host polymer also adversely affected the quality of extracted films. An in situ capacitance process monitoring scheme was developed which indicated that film damage, when observed, was primarily caused by explosive decompression of the solvent from the host polymer.