A novel resist system for enhanced resist spreading in nanoimprint lithography

Imprint lithography is a promising technology for replication of nano-scale features. For semiconductor device applications, Canon deposits a low viscosity resist on a field by field basis using jetting technology. A patterned mask is lowered into the resist fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. There are two critical components to meeting throughput requirements for imprint lithography. The first component uses a similar approach to what is already done for many deposition and etch processes. Imprint stations can be clustered to enhance throughput. The FPA-1200NZ2C is a four station cluster system designed for high volume manufacturing. The second component is resist fill. For a single station, throughput includes overhead, resist dispense, resist fill time, exposure and separation. Resist exposure time and mask/wafer separation are well understood processing steps with typical durations on the order of 0.10 to 0.20 seconds. To achieve a total process throughput of 20 wafers per hour (wph) for a single station (or 80 wph for a four station NZ2C system), it is necessary to complete the fluid fill step in 1.1 seconds. There are several parameters that can impact resist filling. Key parameters include resist drop volume (smaller is better), system controls (which can impact spreading after jetting), Design for Imprint or DFI (to accelerate drop merging) and material engineering (to promote drop spreading after dispense). In addition, it is mandatory to maintain fast filling, even for edge field imprinting. In this paper, we address the improvements made in DFI and material engineering. By optimizing the drop pattern layout and introducing a two component resist system that enhances resist spreading, throughputs of 80 wafers per hour or more are achieved.