Tadayuki Fujiwara

Effect of end group structures of methacrylate polymers on ArF photoresist performances

The relationship between the sensitivity of ArF photoresist and the end group structures of copolymers consisting of (beta) -hydroxy-(gamma) -butyrolactone methacrylate (HGBMA) and 2-methyl-2-adamantyl methacrylate (MadMA) was investigated. The sensitivity is strongly dependent on the kind and amount of end groups. It has been found that the copolymer with relatively non-polar end group structure has higher sensitivity than that with polar end group structure, and that the sensitivity of copolymer with end groups of methylisobutyrate and 1-octhylthio moieties showed approximately three times higher than that of copolymer with end groups of isobutyronitrile and 2-hydroxyethylthio moieties. The difference of sensitivity among these copolymers has been discussed from the view point of the change of development rate attributed to the amount of carboxylic acid groups formed in the resist film by exposure of 193nm light.

Newly developed acrylic copolymers for ArF photoresist

We have developed novel acrylic copolymers for ArF photoresist which have more etching durability than usual. The excellent one of those copolymers in handling contains 8- or 9- methacryloyloxy-4-oxatricyclo[5.2.1.02,6]decan-3-one (OTDMA) and (gamma) ,(gamma) -dimethyl-(alpha) -methylene-(gamma) -butyrolac tone (DMMB). OTDMA is a new methacrylic ester monomer having a lactone unit with bridged structure. DMMB introduces a lactone structure to the main chain of acrylic copolymers. It was suggested that the solubility of monomers depends on the hindrance of their polar group, and the role of the hydrophilic monomers has been discussed from the standpoint of the position of their hydrophilic parts.

Design and development of novel monomers and copolymers for 193-nm lithography

Design and development of novel monomers and copolymers for 193-nm lithography are described. At the present time, 193-nm lithography is required for 65-nm node and below. Novel monomers and copolymers are considered to be candidates for the development of higher performance resist materials. We focused our attention on pattern profile and line edge roughness. In design of novel monomers, molecular orbital calculation was adopted. It was revealed that CN-group has a higher potential than other polar groups. Novel monomers that contain CN-group were designed, synthesized and co-polymerized with traditional acrylate monomers. It is expected that these copolymers could be higher performance resist materials that could be used in 65-nm node and below.

Development of advanced ArF resist using alicyclic methacrylate copolymer: the optimum quenchers for this copolymer

We have investigated alicyclic methacrylate copolymers for positive ArF resist. The resist utilizing developed copolymer had so high sensitivity and so high resolution that we could believe its potentiality to be high. When any quenchers were not added, the limited resolution of the developed resist was by 0.14 micrometer L/S. Therefore we carried out the investigation of quencher in order to improve the resolution of the resist. As a result, it found out that amide compounds were effective as a quencher for this system, and a certain kind of an amide compound made the resist profiles good. Then we studied the relationship between the resist performance and the basicity or the polarity of the basic organic compounds used as quencher.