This paper describes some of the recent advances and applications of biased target deposition for thin film optical coating. Biased target deposition (BTD) is a remote plasma sputtering technique that produces comparable film density without the overspill contamination or low rate generally attributed to ion beam sputtering. This work addresses the application of BTD to a four layer anti-reflective coating analyzed by spectral transmittance, ellipsometry, and secondary ion mass spectroscopy (SIMS). Layers of SiO_2 and Ta_2O_5 were deposited on a silicon substrate using BTD in a reactive sputtering environment. Interfacial abruptness was varied by depositing a low-bias seed layer before transitioning to faster high-bias modes. Modifying target bias with remote plasma enables constant stoichiometry and uniformity under both high and low target bias conditions.
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