Ichiki Takemoto

Standard developer available ArF resist and performance

Alicyclic groups are preferable resin components of ArF resists due to better dry-etching resistance and higher transparency at 193 nm. On the other hand, Alicyclic groups bring poor adhesion of ArF resists during wet development, because of their higher hydrophobic nature. To avoid the peeling problem diluted developer has been suggested to use. However, the compatibility with existing standard developer of i-line and KrF resists is necessary for the mass production. In this paper we compared two kinds of resists for the standard developer (TMAH 2.38%) application. The former has AdCEE unit and norbornene derivative/maleic anhydride alternating copolymer, together with relatively weak organic acid generating PAG. The latter having 2MAdMA/GBLMA copolymer and onium salt PAG shows better lithographic performance.

Positive ArF resist with 2EAdMA/GBLMA resin system

We compared 2MAdMA(2-Metyl-2- Adamantylmethacrylate)/GBLMA((gamma) -butyrolactone methacrylate) resin system and 2EAdMA(2-Etyl-2- Adamantylmethacrylate)/GBLMA resin system. 2EAdMA/GBLMA resin system showed higher sensitivity, dissolution contrast and better adhesion to silicon substrate than 2MAdMA/GBLMA resin system. These results shows that 2EAdMA/GBLMA resin system is suitable for practical ArF positive resist.

Quantitative structure-activity relationships of herbicidal N′-substituted phenyl-N-methoxy-N-methylureas

Abstract Relationships between three types of herbicidal activity of N′-substituted phenyl- N -methoxy- N -methylureas and substitution at the benzene ring were analyzed by the Hansch-Fujita method. First, the Hill inhibitory activity was correlated with electronic (σ) as well as hydrophobic (π) substituent constants. The existence of an optimum value of hydrophobicity for substituents was suggested to reach the target site of action. Second, bliaching activity observed for the 3-substituted but not for 4-substituted compounds was correlated with π, σ, and steric substituent constant, E s . Third, the postemergent herbicidal activity was shown to correlate linearly with the Hill inhibitory activity, p I 50 , and hydrophobic parameter, π.

Molecular resists for EUV and EB lithography

Extreme ultraviolet lithography at a wavelength of 13.5 nm has been prepared for next generation lithography for several years. Of primary concern in EUV lithography is line edge roughness as well as high sensitivity. In recent years, various types of resist, such as protected PHS resin resist and molecular resist, have been investigated. In order to reduce LER, we have studied novel molecular resists which are promising alternative to polymeric photoresists for use as imaging materials with improved resolution and line edge roughness. The work reported in this paper has focused on the development of a new class of chemically amplified molecular resists that are composed of a single molecule which contains all of the different functionalities desired in a chemically amplified resists. For the purpose of improvement of the resist performance, we have designed the resist material of a protected polyphenol derivative (protected Compound A). PAG moiety is bonded to Compound A to achieve uniform PAG density and to control the acid diffusion length in a resist film. We analyzed uniformity of PAG density in a resist film by using gradient shaving preparation and TOF-SIMS analysis. From the TOF-SIMS spectra, the ions intensities of the PAG moiety are almost constant from the surface to the bottom of the film. Therefore, we can conclude that PAG is distributed homogeneously. Under e-beam exposure, a 100nm thick film of the PAG bonded molecular resist resolved lines down to 100nm. We also discussed the new design for molecular resists, their synthesis and lithographic performance.

Tailoring thermal property of ArF resists resins through monomer structure modification for sub-70-nm contact hole application by reflow process

Numerous resolution enhancement techniques have been introduced over the past few years as the design rule decreases rapidly. Among them are thermal reflow, SAFIER and RELACS just to name a few. Resist reflow is one of the simplest processes with a minimum process modification that only requires an additional baking step at or above its glass transition temperature after the contact holes have been developed. Since most of the methacrylic-based ArF resins have Tgs in vicinity of their thermal decomposition temperature, it is not desirable to expose the resins near Tg for a prolonged time. An approach to construct a resin that is physically or thermally viable, yet chemically stable is necessary and the easiest way of achieving this goal is to bring down Tg of the resin significantly so that there would be enough working space between thermal decomposition and glass transition. Out of several conceivable ways to lower the Tgs such as employing acrylic polymers, COMA type polymers etc., we have chosen to maintain the methacrylic platform because of its superior resolution capability. Our design strategy is to work on the pendent groups of methacrylic monomers to make polymer matrix more flexible. Thus, the incorporation of a more flexible unit, such as 2-methyl-2-adamantyloxycarbonylmethyl methacrylate, in our existing copolymer system reduced Tg almost by 30°C. In addition to its thermal property tuning ability, the resist sensitivity also has increased, presumably due to the out-stretched position of an acid labile protecting group for easy access of incoming acid molecules. Our newly developed resists based on the design concept showed a good C/H pattern profile and improved LER by reflow process at sub-70 nm node. We will discuss our newly designed materials in this paper in terms of material properties, resist characteristics and lithographic performances in relation to reflow processes.

Tailoring surface properties of ArF resists thin films with functionally graded materials (FGM)

Our recent research effort has been focused on new top coating-free 193nm immersion resists with regard to leaching of the resist components and lithographic performance. We have examined methacrylate-based resins that control the surface properties of ArF resists thin films by surface segregation behavior. For a better understanding of the surface properties of thin films, we prepared the six resins (Resin 1-6) that have three types fluorine containing monomers, a new monomer (Monomer A), Monomer B and Monomer C, respectively. We blended the base polymer (Resin 0) with Resin (1-6), respectively. We evaluated contact angles, surface properties and lithographic performances of the polymer blend resists. The static and receding contact angles of the resist that contains Resin (1-6) are greater than that of the base polymer (Resin 0) resist. The chemical composition of the surface of blend polymers was investigated with X-ray photoelectron spectroscopy (XPS). It was shown that there was significant segregation of the fluorine containing resins to the surface of the blend films. We analyzed Quantitative Structure-Property Relationships (QSPR) between the surface properties and the chemical composition of the surface of polymer blend resists. The addition of 10 wt% of the polymer (Resin 1-6) to the base polymer (Resin 0) did not influence the lithographic performance. Consequently, the surface properties of resist thin films can be tailored by the appropriate choice of fluorine containing polymer blends.