Bottom antireflective coatings (BARCs) for 157-nm lithography

Bottom anti-reflective coatings (BARCs) are essential for achieving the 65-nm node resolution target by minimizing the substrate reflectivity to less than 1% and by planarizing substrates. We believe that the developments in 157-nm BARC products are on track to make them available for timely application in 157-nm lithography. We have made some significant improvements in resist compatibility and etch selectivity in relation to the latest available 157-nm resists. Two chromophores having desired high light absorbance at the 157-nm wavelength have been identified. The prototype BARC formulations basically meet the critical requirements for workable 157-nm BARCs, including optical properties, thermal stability, photo-stability, etch rate and selectivity, and compatibility with photoresists. The BARCs also show good coating quality and stripping resistance. Another essential feature of the BARCs is that they are formulated in industry-accepted safe solvents. The lithographic profiles of a benchmarked 157-nm photoresist on our prototype BARC LH157B show straight 60-nm L/S patterns. LH157B also exhibited excellent lithography performance as an ArF BARC. Optimization of the BARC formulations is in progress.