Consistently Produce the Highest Index TiO2 FilmsPeter Finn
Telemark Low Pressure Ion Sources consistently produce the highest index TiO2 films at ambient temperatures
Telemark research lab continues to test materials using the Telemark Low Pressure Ion Sources.
TiO2 is a very popular material for interference coatings and is used heavily across our industry. The ability to push the index of TiO2 up should be the goal of all coating operations using this material. Increasing the index affords; less layers to achieve better film properties, faster turn times for high layer count stacks and higher profitability.
Recent work with TiO2 and the Telemark Ion Sources showed consistent indexes for TiO2 films. Indexes of 2.35 – 2.4 or better in the visible region were consistently produced under various conditions. All testing was done at ambient temperatures.
- Telemark found under poor system conditions; system dirty, pumps operating poorly and unstable deposition rates, that consistent indexes of over 2.35 were still achieved.
- Conversely; when the testing was done under best system conditions; system clean, pumping good and stable deposition rates attained, consistent indexes exceeding 2.4 were achieved.
It was also discovered that the starter materials had an impact. Starter materials with less gas were faster to condition, had less spitting and generally were easier to use. Saving time on the conditioning process also increases system throughput.
The Telemark Ion Current Monitor was used in these experiments to track the real-time ion dose at the substrate for each run. This was a very “revealing” piece of data. Every company that uses IAD ebeam processes should have such a device working real-time to assure the films are being deposited under optimum, consistent conditions.
This testing was done with the Telemark ST55 ion source using pure O2 at a distance of 30”. Deposition pressures ranged from 10e-4 for the lower indexes and 10e-5 for the higher indexes.
Information from a few of our partner labs using traditional end hall sources report consistent indexes of 2.25 or less for TiO2 films in the visible region. They also report very long material condition campaigns and very strict system parameters needed to achieve such poor indexes.
The days of using high pressure (10e-4) plasmas from traditional end hall or other “overly expensive” ion sources and settling for lessor high index film results are over.
For a full report on this work and to discuss how the Telemark Technology can improve your films, improve system throughput and profitability, please contact Telemark at email@example.com .