Measurement and Correlation of Ion Beam Current Density to Moisture Stability of Oxide Film Stacks Fabricated by Cold Cathode Ion Assisted Deposition.

Durable and dense dielectric optical stacks, deposited with the assist of a gridded, Kaufman-type ion source have been extensively reported upon. A primary limitation of this technique is a significant reduction of ion source lifetime when high levels of oxygen are required to achieve specific film properties. Cold cathode ion sources, which are capable of continuous operation with 100% oxygen, have traditionally been used in a high current/low energy mode to assist in the fabrication of low absorption, high index oxide films. This work reports on the use of the cold cathode ion source at high energy levels to generate moisture stable thin film optical stacks. The optical properties and moisture stability of optical film stacks made from these oxides are presented as a function of the cold cathode ion source’s operational parameters and the measured ion current density at the surface of the deposited films.