Mask defect is one of the biggest problems in Extreme Ultraviolet Lithography (EUV) technology. EUV mask must be free of small defects, requiring development of new inspection tools and low defect fabrication processes. So, we studied the influences of the defects on the mask for 22 nm line and space pattern. First, we changed the light quality caused by the various wavelength shift, incident angle, and the defect material with different refractive index. Second, we changed the defect size from 20 nm to 16 nm because 18 nm defect is assumed to a critical defect size for 22 nm node. Third, we also changed the defect positions; on top of the absorber, on the valley of the absorber, and at the sides of the absorber. Finally, we simulated the influence for the different shaped defect. A square pillar defect shows very different behavior compared to the more realistic round shaped defect. Defect of higher refractive index gives little influence, while defect of lower refractive index gives larger influence. A more realistic elliptical shaped defect gives less influence compared to square shaped defect. All the defect and EUV parameters will influence to the printability of the defect, but more study is needed to judge whether a certain defect can influence the printed pattern.
In the past several years, ArF immersion lithography has been developed rapidly for practical applications. ArF
immersion lithography is now researched actively and developed for the purpose of implementing the 45-nm technology
node. For the device designs involved immersion lithography, line width roughness (LWR) and film wettability are very
important criteria to control in the point of high resolution and defectivity.
Free radical polymerization in the presence of thiocarbonylthio compounds of general structure Z-C(=S)S-R provides
living polymers of predetermined molecular weight and narrow molecular weight distribution by a process of reversible
addition-fragmentation chain transfer (RAFT). A rationale for selecting the most appropriate thiocarbonylthio
compounds for a particular monomer type is presented with reference to the polymerization of methacrylates, styrenes,
acrylates, acrylamides, and vinyl acetate.
In this study, resist polymers with narrow polydispersity (PD) and controlled molecular structure were prepared using
controlled radical polymerization techniques, such as RAFT polymerization. PD index of polymers showed between
about 1.2 to 1.4 and in some instances, between about 1.1 to 1.2 or less. Additionally, each polymer chain has a RAFT
end group. That is the resulting polymer contains a chain transfer agent (CTA) moiety at each terminal end of polymer
backbone. It is possible that hydrophobic CTAs can be used to decrease the hydrophilicity of resist film.
As the feature size becomes smaller, it is difficult for the lithography progress to
keep pace with the acceleration of design rule shrinkage and high integration of memory device.
Extreme Ultra Violet Lithography (EUVL) is a preferred solution for the 32nm node. In this
paper, we have synthesized two types of polymers. One is based on hydroxy phenol, the other
is based on hydrocarbon acrylate type polymer. We have diversified each polymer type
according to different activation energies for deprotection reaction. In this experiment, we have
observed on the resist lithographic performance such as resolution, LER (Line Edge
Roughness), photo-sensitivity, and out-gassing during exposure. Different properties according
to activation energy were well explained by acid diffusion and polymer free-volume.
ArF Immersion lithography is the most promising technology for 45nm node and possibly beyond. However, serious
issues in ArF immersion lithography for semiconductor mass production still exist. One of the issues is immersion
specific defects, which are caused by photoresist component leaching and residual water droplets. In order to minimize
immersion specific defects, preventing water penetration into the resist film is regarded as an important factor. Several
research groups have reported that higher receding contact angle reduced defectivity. High receding contact angle of
film surface prevent water penetration into the resist film due to the hydrophobic nature. Resist component leaching
phenomenon also can be caused by the water penetration into the film, so hydrophobic resist can reduce leaching
In this paper, to investigate chemical leaching from resist surface, we evaluated the leaching value of PAG anion and
contact angles of various polymers according to their hydrophobicity. Hydrophilicity of a polymer was changed by the
degree of hydrophobic group substitution to polymer chain. We measured receding contact angle with four different
resists composed of water-repellent functiona group. Receding contact angle of resist surface increased as the portion of
water-repellent functional group increased. Also, the leaching amount of PAG anion decreased as the receding contact
angle of film surface increased. We expect that higher receding contact angle prevents chemical leaching from resist film
by repelling water at the surface. We will report detailed results in this paper.
Post exposure bake temperature sensitivity (PEB sensitivity) becomes important as the pattern pitch size shrinks gradually. There are several factors affecting the PEB sensitivity including acidity and diffusion of photogenerated acid, activation energy for deprotection reaction, free volume of base polymer, and so on. Our works were conducted as a part of the basic study for searching influential parameter of PEB sensitivity. We found that PEB sensitivity relies largely on not only acid diffusion parameter, but also the hydrophilicity of base polymer and protection group ratio. Also, we observed that bulkiness of deprotection group has great influence on PEB sensitivity. Detailed results will be reported in this paper.