This presentation summarizes the relationships between resist outgassing and contamination deposition for EUV
resists, in the case of EUV irradiation with high illumination intensity (>100mW/cm2). These relationships were
obtained by determining the resist outgassing species by gas chromatography-mass spectroscopy (GC-MS) and the
contamination on optical elements by witness sample testing.
This paper summarizes the development of EUV resists based on various new materials: the lithographic evaluation results of EUV resists from resist material manufacturers using the small field exposure tool (SFET). We discuss the screening results of new resin materials based on
calixresorcinarene, "Noria" and fullerene.
This paper summarizes the investigation of the evaluation methods of EUV resist outgassing based on pressure-rise,
gas chromatography mass spectrometry (GC-MS) and quadrupole mass spectrometry (QMS). We discuss the merit
and demerit about these three methods and propose an optimal employment of each evaluation method. In addition,
detail results of resist outgassing evaluated from GC-MS were reported.
Extreme ultraviolet (EUV) lithography is the leading candidate for the manufacture of semiconductor devices at the hp-
22-nm technology node and beyond. The Selete program covers the evaluation of manufacturability for the EUV
lithography process. So, we have begun a yield analysis of hp-2x-nm test chips using the EUV1 full-field exposure tool.
However, the resist performance does not yet meet the stringent requirements for resolution limit, sensitivity, and line
edge roughness. We reported on Selete standard resist 4 (SSR4) at the EUVL Symposium in 2009. Although it has better
lithographic performance than SSR3 does, pattern collapse limits the resolution to hp 28 nm. To improve the resolution,
we need to optimize the process so as to prevent pattern collapse. An evaluation of SSR4 for the hp-2x-nm generation
revealed that a thinner resist and the use of a TBAH solution for the developer were effective in mitigating this problem.
Furthermore, the use of an underlayer and an alternative rinse solution increased the exposure latitude by preventing
pattern collapse when the resist is overexposed. These optimizations improved the resolution limit to hp 22 nm.
In ArF immersion lithography process, material surface and wafer bevel hydrophobicity is an important factor in
minimizing defects and water droplet residue. The application of topcoat and topcoat-less materials has been reported to
increase hydrophobicity. The hydrophobicity of wafer bevel plays an important role in the effective inhibition of the
immersion fluid from leaking to the wafer backside. The hydrophobicity at the wafer bevel can be optimized through
the optimization of the film edge cut height (FECH), which is defined as the distance from the film surface down to the
film cut edge at the wafer bevel. Special bevel rinse modules have been introduced in track systems to control FECH
with a high degree of accuracy. In this work, various types of FECH were analyzed and measured using a newly
developed inspection system. Based on these results, the quantification of the FECH for all the materials analyzed was
It was found that FECH changed depending on the bevel rinse condition applied. For example, wafer rotation and bevel
rinse flux significantly influence FECH. These results show the possibility of controlling the FECH for optimization.
Proc. SPIE. 6151, Emerging Lithographic Technologies X
KEYWORDS: Lithography, Electron beam lithography, Etching, Photomasks, Extreme ultraviolet lithography, Critical dimension metrology, Photoresist processing, Semiconducting wafers, Failure analysis, Back end of line
In this study, we have demonstrated a resist process to fabricate sub 45-nm lines and spaces (L&S) patterns (1:1) by using electron projection lithography (EPL) for a back-end-of-line (BEOL) process for 45-nm technology node. As a starting point we tried to fabricate sub 45-nm L&S (1:1) patterns using a conventional EPL single-layer resist process. There, the resolution of the EPL resist patterns turned out to be limited to 70 nm L&S (1:1) with aspect ratio (AR) of 3.3 which was caused by pattern collapse during the drying step in resist develop process. It has been common knowledge that pattern collapse of this type could be prevented by reducing the surface tension of the rinse-liquid and by decreasing the AR of the resist patterns. Therefore, we first applied a surfactant rinse to a single-layer resist process that could control the pattern collapse by its reduced surface tension. In this experiment, we used the ArF resist instead of the EPL resist because the surfactant that we were able to obtain was the one optimized to the ArF resist materials. From the results of ArF resist experiments, it was guessed that it was difficult for the EPL resist to obtain the L&S patterns with AR of 3.5 or more even if we used the surfactant optimized to the EPL resist. And we found that it was considerably difficult to form 45-nm L&S patterns with AR of 5.1 that was our target. Next, we evaluated a EPL tri-layer resist process to prevent pattern collapse by decreasing the AR of the resist patterns. Because in a tri-layer resist process the purpose of the top-layer resist is to transfer pattern to the middle-layer, a thinner top-layer resist was selected. By using the tri-layer resist process we were able to control the resist pattern collapse and thus were successful in achieving 40-nm L/S (1:1) top-layer resist patterns with AR of 2.3. The process also gave us 40-nm L&S (1:1) patterns after low-k film etching. And moreover, using our tri-layer resist process we were able to fabricate a wiring device with Cu/low-k. Although it was our first attempt, the process resulted in a high yield of 70 % for a 60-nm (1:1) wiring device. As a part of our study we conducted failure analysis of the results of our experiment. We found that the failures were located at the edge of the wafer and might originate in the bottom-layer pattern collapse. We thought that the wiring yield could be increased by control the bottom-layer pattern collapse. These findings indicated that our tri-layer resist process had a high applicability for device fabrication in BEOL.