The Advantages of Nanoimprint Lithography for Semiconductor Device Manufacturing

Imprint lithography is an effective and well known technique for replication of nano-scale features. Nanoimprint lithography (NIL) manufacturing equipment utilizes a patterning technology that involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the 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. The technology faithfully reproduces patterns with a higher resolution and greater uniformity compared to those produced by photolithography equipment. Additionally, as this technology does not require an array of wide-diameter lenses and the expensive light sources necessary for advanced photolithography equipment, NIL equipment achieves a simpler, more compact design, allowing for multiple units to be clustered together for increased productivity. Previous studies have demonstrated NIL resolution better than 10nm, making the technology suitable for the printing of several generations of critical memory levels with a single mask. In addition, resist is applied only where necessary, thereby eliminating material waste. Given that there are no complicated optics in the imprint system, the reduction in the cost of the tool, when combined with simple single level processing and zero waste leads to a cost model that is very compelling for semiconductor memory applications. Any new technology to be introduced into manufacturing must deliver either a performance advantage or a cost advantage. Given the risks associated with this introduction, generally a combination of both performance and cost advantage is preferred. In this paper both performance attributes and cost are discussed. NIL resolution and linewidth roughness do not have the limitations of conventional projection lithographic method. Furthermore, it is not subject to patterning restrictions that forced the industry towards one dimensional patterning. A cost example case of 20nm dense contacts is also presented. Because NIL utilized a single step patterning approach, process costs are substantially reduced relative to ArF immersion lithography. Overall, NIL currently realizes a 28% cost advantage for this case, but as mask life continues to improve, the cost advantages become much more significant.