Liyuan Wang

Novel One-Component Positive-Tone Chemically Amplified I-Line Molecular Glass Photoresists

Maleopimaric acid, cycloaddition reaction product of rosin with maleic anhydride, was reacted with hydroxylamine to afford N-hydroxy maleopimarimide, which was then further esterified with 2-diazo-1-naphthoquinone-4-sulfonyl chloride (2,1,4-DNQ-Cl) to give N-hydroxy maleopimarimide sulfonate. The carboxylic acid group of the compound was then protected by the reaction of this compound with vinyl ether compounds to give the corresponding molecular glass compounds. Upon irradiation to 365 nm light, the 2,1,4-DNQ group undergo photolysis not only to be converted into indene carboxylic acid but also generate a few amount of sulfonic acid which can catalyze the deprotection of the acid labile group. So, novel one-component positive-tone chemically amplified i-line photoresists can be formed by the molecular glass compounds. The lithographic performance of the resists was evaluated using i-line exposure system with high photosensitivity and resolution.

Novel ester acetal polymers and their application for positive-tone chemically amplified i-line photoresists

Polyaddition reactions of N-hydroxy maleopimarimide with divinyl ether compounds were carried out to give novel polymers with ester acetal linkages in the main chain. The polymers have good solubility in common organic solvents and relatively high Tg temperatures. The number-average molecular weights of the polymers range from 4000 to 5500, with Mw/Mn of 1.7–2.3. The thermal decomposition temperatures of the polymers are above 220 °C. The film of the obtained polymers showed excellent transparency to UV light above 230 nm. The ester acetal linkage of the polymer chain can be cleaved in the presence of strong acid under mild heating. Making use of the high acidolytic activity of the polymers, positive-tone chemically amplified i-line photoresists can be formed from them and 2,1-diazonaphthoquinone-4-sulfonate, in which the well known photoactive compound can also function as a photoacid generator. The photolithographic performance of the photoresists was evaluated using an i-line exposure system with high photosensitivity and resolution.

The preparation of a novel polymeric sulfonium salt photoacid generator and its application for advanced photoresists

With poly(4-hydroxylstyrene) (PHS) as a raw material, a new type of polymeric photoacid generator (PAG) is synthesized with sulfonium perfluoroalkyl sulfonate groups bonded onto part of the benzene rings. The phenolic hydroxyl groups are esterified to increase the solubilities of the polymeric sulfonium salts in organic solvents. Upon irradiation to 254 nm light, the sulfonium units in the polymer effectively decompose to generate sulfonic acid. The photolysis is confirmed by UV spectroscopy and the generation of sulfonic acids which catalyze the decomposition of the t-BOC protection group of the polymeric PAGs. Making use of the polymeric PAGs, positive-tone chemically amplified 248-nm photoresists can be formed by them and ester acetal polymer with high acidolytic activity. The photolithography performance of the photoresist was evaluated using a KrF laser exposure system with high photosensitivity and resolution. This novel kind of polymeric sulfonium salt PAG is applicable for advanced chemically amplified resist materials.

Novel 193-nm positive photoresist composed of ester acetal polymer without phenyl group

1,3-adamantanedicarboxylic acid and acrylpimaric acid were reacted with an aliphatic divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, to give novel ester acetal polymers without phenyl group. These polymers can be dissolved in common solvents and possess high thermal stability. The ester acetal polymer can be quickly decomposed at the presence of strong acid generated by PAG above 100°C and become easily soluble in dilute aqueous base. Two-component photopolymer consisting of the ester acetal polymer and PAG can be used as positive photoresists. The polymer derived from 1,3-adamantanedicarboxylic acid displayed higher transparency at 193 nm and can be used for 193 nm photoresist.

An i-line molecular glass photoresist for high resolution patterning

Calix[4]resorcinarene was functionalized by photoactive 2-diazo-1-naphthoquinone-4-sulfonyl chloride (2,1,4-DNQ-Cl) to form a single-component non-chemically amplified i-line molecular glass photoresist. This single-component molecular glass photoresist afforded clean 100 nm line patterns with i-line interference lithography.

Two-component photoresists based on acidolytic cleavage of novel ester acetal polymer

The reaction of acrylpimaric acid and several divinyl ether compounds, including 1,3-Bis(2-(vinyloxy)ethoxy)benzene, 2,2-bis(4-[2-(vinyloxy)ethoxy]phenyl)propane, and 1,4-Bis(2-(vinyloxy)ethoxy)benzene, can take place in the presence of organic solvents to form novel ester acetal polymer with the average molecular weight of 4000-6000(Mn) measured by GPC. These polymers can be easily dissolved in common solvents and show high thermal stability. The ester acetal polymers can be quickly acidolyzed at the presence of strong acid generated by PAG above 100oC and become easily soluble in dilute aqueous base. Two-component positive photoresists can be formed by the ester acetal polymer and PAG. The lithographic performance of the resist material composed of the ester acetal polymer and a sulfonium triflate PAG was studied on i-line exposure instrument. Clear pattern with 2 &mgr;m resolution was obtained and the photosensitivity was below 20mj/cm2.

Study on a few α-disulfone compounds as photoacid generators

In this work a few α-disulfone compounds with different substituents were prepared by a simple nitric acid oxidation of corresponding disulfonylhydrazines which were prepared by reaction of sulfonyl chloride and aqueous hydrazine. Most of the compounds are soluble in common organic solvents for photoresists. The thermal decomposition temperatures of the compounds were detected to be above 190 °C. The UV absorption spectra of the α-disulfone compounds were measured with the absorption peaks (λmax) around 250 nm. Quantum yields of the disulfone compounds in solution were determined to be in the range of 0.4-0.6 with low pressure Hg lamp as exposure light source.

Novel polymeric sulfonium photoacid generator and its application for chemically amplified photoresists

Chemically amplified resists (CARs) which involved the photoacid generator (PAG) have been widely used because of the high sensitivity. The inherent incompatibility between the polymer matrix and small molecular PAGs leads to problems including PAG phase separation, non-uniform initial PAG and photoacid distribution, as well as acid migration during the post-exposure baking (PEB) processes. The polymeric PAGs based resist systems which incorporated the PAG units into the main chain showed improved lithographic performance, such as faster photospeed and higher stability, lower outgassing, and lower LER than corresponding blend resists. In this paper, a novel type of polymeric PAGs based on poly (4-hydroxylstyrene) (PHS) was discussed. Chemically amplified photorssists were formed by the polymeric PAG and other film forming material containing acid labile groups. The polymeric PAGs showed advantage over the common small molecular PAG and patterns with 180 nm resolution was obtained in the 248-nm lithography.

A novel single-component resist based on poly (4-hydroxylstyrene) applicable for EUV lithography

With the growing demand of the electronics industry for smaller, higher resolution features, next generation lithographic techniques, such as Extreme Ultraviolet(EUV) lithography have caused widely attention of the scientists. As the EUV absorption is determined by the nature of atoms but not by the structure of molecules, poly(4- hydroxylstyrene) (PHS) based resists can be employed in EUV lithography. Single-component resist system is constructed by the polymers consisting of two major functional components, photoacid-generating unit and the acidlabile group, which can help to alleviate the problem derived from the poor compatibility in multi-component resist system. In this paper, PHS was used as raw material to prepare a novel polymer with sulfonuium salt group attached on part of the benzene rings and the hydroxyl groups partly protected by t-BOC, which can be used as a novel kind of single-component CA resist. The polymer can be dissolved in common resist solvents. The thermal stability, photolysis and photolithographic property of the resist material were investigated.

Molecular glass positive i-line photoresist materials containing 2,1,4-DNQ and acid labile group

Recent years increasing attention has been given to molecular glass resist materials. In this paper, maleopimaric acid, cycloaddition reaction product of rosin with maleic anhydride, was reacted with hydroxylamine and then further esterified with 2-diazo-1-naphthoquinone-4-sulfonyl chloride to give N-hydroxy maleopimarimide sulfonate. The carboxylic acid group of the compound was then protected by the reaction of this compound with vinyl ethyl ether or dihydropyran. Thus obtained compounds were amorphous. When irradiated with i-line light, the 2,1,4-DNQ group undergo photolysis not only to give off nitrogen gas but also generate sulfonic acid which can result in the decomposition of the acid labile group. So, a novel chemically amplified positive i-line molecular glass photoresists can be formed by the compound and other acidolytic molecular glass compounds. The lithographic performance of the resist materials is evaluated.