In-line chemical shrink process for 70 nm contact hole patterns by the room-temperature electrostatic self-assembly

Electrostatic self-assembly (ESA) is combined with optical lithography to develop a novel process to form 70nm space patterns to overcome the resolution limit of ArF lithography with numerical aperture (NA) of 0.75. It is proven that patterned photo resist are useful template with specific topography to undergo the subsequent ESA. Weak polyelectrolytes are shown to control the attachment amount by adjusting pH. Puddle-assembly is applied instead of spin- or dip-assembly considering pattern profile and practicality to be used in the real FAB environment. With optimized composition and assembly method, it is successful to form 70 nrn spaces patterns by ESA-induced chemical attachment above 45 rim, combined with ArF lithography of 0.75 NA. Since it works at room temperature without extra process unit after exposure and development, it overcomes the disadvantages of the conventional chemical shrink processes such as thickness loss, dependence on pattern and photo resist, and throughput lowering. In addition, in-wafer uniformities are comparable to that of forming 120 nm spaces patterns with only ArF lithography, which proves that the combination of ESA and optical lithography can be a potentially and practically alternative way of forming uniform 70nm spaces patterns over 200 mm substrates. It also means that now it is time for top-down and bottom-up approaches to meet together to access nano world.