In this work, we connected the analytical determination of the EUV Dill C parameter for different photodecomposable base quencher (PDB) architectures using a standard addition method, the influence of the underlying hardmask on postdevelop EUV resist residue formation, and the vertical PAG and PDB concentration profile throughout the depth of the film determined by GCIB-TOF-SIMS for a model EUV resist system. The collected experimental data was used to feed a resist patterning simulation engine, in order to understand the additive effect of component distribution and efficiency on EUV stochastics and its potential impact on defect control. Our results unveiled a link between PDB quantum yield and nanoscopic material distribution uniformity. In parallel, a differentiating behavior was observed among inorganic underlayers: metal oxide hardmasks (HMs) invariably induced more resist residue than non-metallic HMs. Last, a specific example of joint PAG and PDB concentration depletion at the resist-substrate interface was related to a potential increase in microbridge defectivity as a result of poor stochastic counts.
At IBM, one of the focus items for EUV patterning development is to enable the fullest extent of scaling to a second EUV node while maintaining single-exposure levels. The challenge for the next node of EUV patterning has been with attaining acceptable defectivity levels that can enable electrical yield at pitches 32nm and below. For single-expose EUV, the primary detractors to sub-32nm pitch yield are typically microbridging and line break defects, which have different root causes but can exist in the same dose range. Since the etch strategies for mitigating one of these defect types will result in exacerbating the other, the burden to improve defectivity cannot be placed solely on the pattern transfer process. Resist scumming, which is the root cause of microbriging, can be modulated through interactions with the resist-hardmask interface. The lack of acid at the substrate interface causes resist scumming, and therefore increasing the acidity at the resist hardmask interface can be expected to mitigate post-litho microbridge defects. As the number of EUV photons are significantly less compared to DUV exposures due to the high energy contained in each photon, an extra acid boost can also help to address the stochastics failures that dominate EUV patterning. This paper will demonstrate the concept of modulating the resist-hardmask interaction through surface activation layers, and show the subsequent effects on patterning process window and microbridging defectivity toward yield at pitches <32nm.
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