Electron beam-generated plasmas in NF3 environments for the passivation of UV/O/IR mirrors

Abstract

In previous work we demonstrated the feasibility of a new plasma process based on electron beam-generated plasmas in SF6 environments that effectively passivates the surface of aluminum mirror samples for applications in the UV/O/IR (ultraviolet/optical/infrared) by removing the native oxide layer and producing an AlF3 passivation layer with tunable thickness. This process provides good results in terms of far ultraviolet reflectivity, environmental stability, uniformity, polarization aberration, surface roughness, and does not require elevated substrate temperatures or ultra-high vacuum conditions. In this communication we show that, in addition to these characteristics, Al mirrors can be passivated faster with NF3 than with SF6 over a wide range of process parameters without the loss of optical performance independent of the working-gas choice adopted for the plasma.