Enabling EUV Resist Research at the 1x and Smaller Regime

Abstract

With the slipping of the insertion node for extreme ultraviolet lithography, demands on resist resolution have increased further stressing sensitivity requirements. A variety of resists, both chemically amplified and not, have been developed meeting resolution needs, but falling short on sensitivity and line-width roughness (LWR). Note that resolution is an absolute mandatory requirement, the true tradeoff that must be considered is between sensitivity and contact hole printing is a crucial application for extreme ultraviolet lithography and is particularly challenged by resist sensitivity due to inherent inefficiencies in darkfield contact printing. Checkerboard strong phase shift masks have the potential to alleviate this problem through a 4× increase in optical efficiency. The feasibility of this method is demonstrated using the SEMATECH-Berkeley Microfield Exposure Tool pseudo phase shift mask configuration and preliminary results are provided on the fabrication of an etched multilayer checkerboard phase shift mask.

Stochastics and EUV Patterning in the 1x-nm Regime

“…As previously reported [11], the MPPM model has been shown to be a good predictor of both mean-field (non-stochastic) effects as well as overall stochastics. Here we use the model ability to isolate specific stochastic effects to study the relative importance of the various terms described above.…”

“…If we instead assume a sensitivity of 80 mJ/cm 2 and a chemical blur of 7 nm (a parameter that has been demonstrated experimentally [11]), while keeping the other parameters as described for Table 3, the MPPM shows that a CDU of 1.2 nm can be achieved. Figure 3 shows the MPPM output.…”

“…Dose requirements for contacts, however, can be mitigated through the implementation of a checkerboard chromeless phase shift masks [9][10][11][12]. EUV aerial image microscopy [11] has been used to report on the feasibility of this method for dose reduction. Demonstration of the method has now been extended to lithographic patterning using the Berkeley MET.…”

“…These requirements, however, can be mitigated through the implementation of a checkerboard chromeless phase shift masks [9][10][11][12]. Using this method, a throughput gain of 8X has been demonstrated using an EUV aerial image microscope [11,13].…”