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What makes the COPRA so unique for the assist in precision optics?
The independent control of Ion Energy and Ion Current Density as a function of rf-power makes the COPRA so important for the next innovation step in precision optics thin film deposition. It is well known that the Energy of the ions itself is responsible for the required densification during deposition whereas the current density just needs to be sufficient high enough. Ions with kinetic energies of more than 15 eV can already overcome all surface binding energies and densification will take place , but if the ion energies are to high above 150eV re-sputtering and defect generation occurs. The COPRA plasma assist allows one to operate with ion energies which only will cause densification without creating defects and simply by increasing the ion current density by increasing the rf-power leads you to a thermally stable drift free Oxide.
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