Closed field magnetron sputter deposition of carbide and nitrides for optical applications

17 April 2008

Magnetron Sputtering has many advantages over conventional evaporation processes for the deposition of carbides and nitrides for optical applications. The sputtering process is “cold”, making it suitable for use on the widest range of substrates including temperature sensitive substrates and polymers. Moreover, the drum format provide more efficient loading for high throughput production.

In contrast to previous reactive dc sputtering strategies the Closed Field process does not require a separate ion or plasma source for activation. Neither does it require the vacuum chamber to be separated by vacuum pumps or baffles into deposition and reaction zones. Reaction occurs on the target and all the way round the substrate carrier resulting in low absorption.

The use of the Closed Field and unbalanced magnetrons creates a magnetic confinement that extends the electron mean free path leading to high ion current densities. The combination of high current densities with ion energies in the range ~30eV creates optimum thin film growth conditions. As a result the films are dense, spectrally stable, supersmooth and low stress.

This paper presents optical, durability and stress data for CFM sputtered carbides and nitrides.