Advanced underlayer film to enhance the productivity of nanoimprint lithography

To improve the throughput of inkjet-type nanoimprint lithography, reduction of a resist filling times is essential. Highly permeable underlayer films reduce the resist filling time by rapidly defoaming trapped gas. The gas permeability of helium and air in several conventional underlayer films was experimentally evaluated by measuring defoaming speeds; however, the use of helium is an expensive solution. The defoaming speed of a particular underlayer film and air was found to be about three times faster than a conventional underlayer film and helium. Validating this combination of film and gas, a throughput of over 100 wafers per hour and low-cost operation in air were realized without deteriorating the underlayer’s performance as a hard mask. Understanding the theoretical background of the interactions between underlayer films and gases enabled us to realize an underlayer film with high gas permeability for the air.