High density plasma etching of Ta₂O₅-selectivity to Si and effect of UV light enhancement

Etch rates up to 1200 Å·min^-1 for Ta₂O₅ were achieved in both SF₆/Ar and Cl₂/Ar discharges under Inductively Coupled Plasma conditions. The etch rates with N₂/Ar or CH₄/H₂/Ar chemistries were an order of magnitude lower. There was no effect of post deposition annealing on the Ta₂O₅ etch rates, at least up to 800°C. Selectivities to Si of ∼1 were achieved at low source powers, but at higher powers the Si typically etched 4-7 times faster than Ta₂O₅. UV illumination during ICP etching in both SF₆/Ar and Cl₂/Ar produced significant enhancements (up to a factor of 2) in etch rates due to photo-assisted desorption of the TaF_x products. The UV illumination is an alternative to employing elevated sample temperatures during etching to increase the volatility of the etch products and may find application where the thermal budget should be minimized during processing.