Optimization of Amorphous Carbon-Deposited Antireflective Layer for Advanced Lithography

Critical dimension variation due to the multiple interference effect is the greatest problem for improving the actual resolution limit in optical lithography. To overcome this problem, amorphous carbon-deposited antireflective layer has been developed. This paper reports on the results of optimization for the antireflective layer film and application to advanced lithography. First, we optimized the deposition process of antireflective layer by measuring the reflectivity. Second, we applied the antireflective layer films in i-line (365 nm) and KrF excimer laser (248 nm) lithography. With the antireflective layer films, the reflectivity from the substrate reduces to less than 20%, which leads to a multiple interference eff ect of less than 1/7. With optimized antireflective layer films, resolution and depth-of-focus are almost same as those of the films without antireflective layer.