Recently, many fluorine compounds are used widely in photolithography. We synthesized some novel fluorinated
polymers for application in 193-nm lithography and 193-nm immersion lithography. Their fundamental properties were
characterized, such as transparency at 193-nm (wavelength) and solubility in water and a standard alkaline developer.
High transparency, i.e., absorbance better than 0.2 pm-' at 193-nm wavelength, was achieved. The dissolution
behaviors of them were studied by using the Quartz Crystal Microbalance (QCM) method. Several polymers dissolved
in water and showed high transparency and a low refractive index by a wavelength of 193-nm. These results show that
their polymers were able to apply to top anti reflective coating (TARC). The dissolution rates of the fluoropolymers in
water and a 0.262N can be controlled by optimizing counter monomers containing hexafluoroisopropanol (HFA) unit,
carboxylic acid unit and so on. In addition, we have collect water contact angle and sliding angle data. This data shows
that fluoropolymers can be used as top-coats for 193-nm immersion lithography resists.
Shrinking design rules have decreased film thickness specifications and are creating challenges as multi-layer structures and new materials are introduced. Film thickness measurement is one of these challenges that must be addressed. Not only are the structures and materials challenging to measure but in the 300mm wafer process it is required to implement these measurements on small test pads to eliminate dummy wafers and save costs. To meet these requirements, Dainippon Screen Mfg. Co., Ltd. has developed a spectroscopic ellipsometer, RE-3200, which can measure several parameters with a spot size down to 30um. This state-of-the-art film thickness measurement tool has a unique design to support spectroscopic ellipsometry and also optical interferometry and monochromic ellipsometry(optional). The advantages include high long-term repeatability, high accuracy, short measurement time, and low COO. The simple optics does not require any components between polarizers and ensure high optical efficiency and stability. The high-precision aspheric mirrors are developed specifically for this system and allow the measurement of the small areas on the device. In addition, the use of high-contrast polarizers minimizes measurement errors. The RE-3200 system is also strongly recommended for scatterometry applications.
In this paper, the optical design and performance of RE-3200 including measurement results will be presented.
Various fluorinated polymers were synthesized for application in 193-nm immersion lithography with the goal of improving 157-nm photoresist performance. Their fundamental properties were characterized, such as transparency at 193-nm and 157-nm (wavelength) and solubility in water and a standard alkaline developer. High transparency, i.e., absorbance better than 0.3 μm-1 at 193-nm wavelength, was achieved. The dissolution behaviors of them were studied by using the Quartz Crystal Microbalance (QCM) method. We find that the dissolution rate of Poly(norbornene-2-fluoro-2-hexafluoroalchol) (PNB1FVIP) in 0.065N tetramethylammonium hydroxide (TMAH) was >200 times (nm/s) faster than that of the copolymer of tetrafluoroethylene (TFE) and norbornene-2-fluoro-2-hexafluoroalchol (TFE/NB1FVIP). A resist based on TFE/NB1FVIP was able to delineate 75 nm dense lines by exposure at 193-nm (wavelength) with an alternating phase shift mask using a 0.75 NA ArF scanner. The dissolution rates of the fluoropolymers in water and a 0.262N and 0.065 TMAH can be controlled by optimizing counter monomers containing hexafluoroisopropanol (HFA) unit, carboxylic acid unit and so on. In addition, we have collect water contact angle data. This data shows that fluoropolymers can be used as resist cover materials for 193-nm immersion lithography.
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