Yasuo Shimizu

Image Reversal Trilayer Process Using Standard Positive Photoresist

Conventional trilayer schemes alleviate the decreasing photoresist budgets as well as satisfy the antireflection issues associated with high NA imaging. However, a number of challenges still exist with standard trilayer processing, most notable among which is the lack of broad resist compatibility and trade-offs associated with improving Si content, such as stability and lithography performance. One way to circumvent these issues is to use a silicon hard mask coated over a photoresist image of reverse tone to the desired pattern. Feasibility of this image reversal trilayer process was demonstrated by patterning of trenches and contact holes in a carbon hard mask from line and pillar photoresist images, respectively. This paper describes the lithography, pattern transfer process and materials developed for the image reversal trilayer processing.