WET-DEVELOPED BILAYER RESISTS FOR 193-NM EXCIMER LASER LITHOGRAPHY

A high-contrast resist process using polysilynes has been developed for 193-nm excimer laser lithography. Copolymerization allows for control of both polymer molecular weight and the net polymer solubility parameter. Optimal formulations yield sensitivities of 35-60 mJ/cm2 and line-edge roughness of <20 nm. Addition of sensitizers into the resist further improves sensitivity and values from 5 to 30 mJ/cm2 have been demonstrated. Use of high-density, low-bias etching sources for the oxygen-plasma pattern transfer improves process windows. For example, etch rate selectivities of 80:1 for the planarizing layer versus the polysilyne imaging layer have been observed even when the planarizing layer etch rate exceeds 1 mum/min. Under these conditions, the exposure latitude is 40% for k1=0.57 and the development latitude is 100% (20+/-10 s) for 10% linewidth control.