Process for deposition of AlF3 thin films

Area of Science:

• Materials Science
• Thin Film Deposition
• Optical Coatings

Background:

• Aluminum fluoride (AlF(3)) is a crucial material for optical coatings.
• Conventional methods for AlF(3) thin film fabrication often rely on expensive fluoride compounds.

Purpose of the Study:

• To develop a more economical fabrication process for AlF(3) thin films.
• To investigate the impact of sputtering parameters on the optical and microstructural properties of AlF(3) thin films.
• To explore alternative deposition and annealing techniques for AlF(3) thin films.

Main Methods:

• Fabrication of AlF(3) thin films using pulsed DC magnetron sputtering with an aluminum target.
• Systematic variation of carbon tetrafluoride (CF(4)) flow rates and sputtering powers.
• Characterization of optical properties (e.g., extinction coefficient) and microstructure.
• Investigation of deposition at different substrate temperatures and UV light annealing.

Main Results:

• Optimized sputtering conditions (20 W power, 110 SCCM CF(4) flow) at room temperature yielded AlF(3) films with excellent optical quality.
• Achieved an extinction coefficient below 7 x 10(-4) at 193 nm.
• Demonstrated the feasibility of using an inexpensive high-purity aluminum target.

Conclusions:

• Pulsed DC magnetron sputtering with an aluminum target offers a cost-effective route to high-quality AlF(3) thin films.
• The developed method provides a viable alternative to conventional deposition processes for optical applications.
• Further research into substrate temperature effects and UV annealing can further optimize film properties.