Background In advanced integrated circuit (IC) manufacturing, photoresist stripping in the back-end of line (BEOL) is achieved through a process which involves dry ashing and wet cleaning. The rinsing and drying of the wafer also takes place. These processes are time consuming and involve a significant amount of energy and water. Moreover, wet processes are limited in their effectiveness of removing residues, and can have some damaging effects; the swelling of porous materials is one example. The use of Supercritical Carbon Dioxide (extraction) - scCO2 – could be a solution. This process has liquid-like solvating properties, but is also highly diffusive and has no surface tension. ScCO2 cleaning offers the potential for effective residue removal and rinsing/drying of the wafer in a single step. Objectives The OMERUS project set out to demonstrate a Supercritical CO2 (scCO2) cleaning prototype in a semi-industrial environment in which 200mm sized wafers are processed. The project was to assess particle cleanliness and compatibility with advanced porous materials, which are the major potential obstacles for an introduction of this technology on an industrial scale. If proved successful, the environmental benefits of using this process would be significant in terms of energy and water saving. CO2 is non-toxic, non-hazardous and the solubility properties enable it to be recycled. During the strip and clean process no water rinsing or drying is necessary. The beneficiary estimated that water consumption for a standard wafer fabrication would be reduced by about 200 000 litres per week or 10 million litres per year. Results The OMERUS project was the first attempt to demonstrate the application of the scCO2-based technology in a real industrial manufacturing environment. While the project did have successful results regarding particle contamination and material compatibility, disappointing results were obtained for metal contamination on the wafers and the scCO2 tool itself. The following key results were reported by the beneficiary: The 'super clean' cleaning process was very difficult to scale up from a lab-scale reactor to an industrial-sized reactor. Background contamination was difficult to control and was too high, making it incompatible with the high cleanliness requirements of the Integrated Circuit manufacturing industry. The prototype hardware (scCO2 tool) was not sufficiently reliable: problems included leaks, control software, etc. Clearly additional work is needed by tool manufacturers (that operate outside the IC manufacturing sector) before this technology is proved successful for IC manufacturing. The scCO2 seems to be 'ahead of its time' for application at the IC manufacturing scale. To conclude, due to the disappointing results of the project and the lack of interest by the industry for the scCo2 technology, the future commercialization of this technology is questionable. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).