Characteristics of low E a 193-nm chemical amplification resists

Abstract

Polymers with methyl acetal ester moiety in the side chain as acid labile protecting group were synthesized and their thermal property, plasma stability and chemical amplification (CA) positive-tone resist characteristics were investigated. 2-Admantyloxymethyl (AdOM) groups in the copolymer indicated lower glass transition temperatures and higher thermal decomposition temperatures than those of 2-methyl-2-admantyl (MAd) groups in the copolymer. AdOM polymer film showed smooth surface roughness after Ar plasma exposure compared with MAd polymer film due to the high thermal stability. The activation energies (E a ) of these deprotection reactions were calculated from Arrhenius plots of these deprotection reaction rate constants. In the low post exposure bake (PEB) temperature region, the E a of these resists decreased in the order MAd > AdOM. The low E a methyl acetal resists displayed good thermal flow resist characteristics for contact holes printing. In addition, the low E a methyl acetal resist achieved a wide exposure latitude of 8.1 % and depth of focus of 400 nm for printing 80 nm 1:1 dense line pattern using NSR-306C (NA 0.78, 2/3 annular). Furthermore, the 65 nm 1:1 dense lines using ASML XT1400 (NA 0.93, C-Quad) for low E a methyl acetal resist pattern showed no tapered and no footing profiles and small roughness on the lines pattern sidewall was observed. 1, INTRODUCTION193 nm lithography including immersion lithography is drawing attention as the successor of optical lithography for the technology nodes of 65 nm, 45 nm, and possibly even beyond 32 nm. 1,2) Therefore, there has been many researches for the base polymer and monomer materials for 193 nm CA positive-tone resists. It is generally known that a suitable protecting group plays an important role in obtaining a good lithographic performance for CA positivetone resist. 3) In our previous work we reported effects of the newly bulky methyl acetal ester as acid labile protecting group on resist characteristics of methacrylate polymers and the relationship between the protecting group structure and deprotection reaction mechanism. 4-6) These results suggest that the newly bulky methyl acetal ester protecting group is effective for further controlling good lithographic performance such as exposure sensitivity, line-edge roughness and PEB sensitivity due to the lower E a compared with tertiary alkyl ester protecting group. However, the relationship between the methyl acetal ester protecting group structure and thermal property of copolymer was not fully discussed. In recent years many papers on low E a CA resist and thermal property of 193 nm CA resists have been reported for the purpose of applying immersion lithography process, thermal flow process and plasma cure process. [7][8][9][10][11] In this paper we report thermal property, plasma stability, deprotection reaction mechanism and high lithographic performance for low E a methyl acetal resist. 2, EXPERIMENT Materials2-Methyl-2-adamantyl methacrylate (M) and γ-butyrolactone-2-yl methacrylate (G) we...

EUV Resist Materials Design for 15 nm Half Pitch and Below

“…This tendency is consistent with previous reports about the deprotection reaction of typical chemically amplified resist [18]. In general, reaction-diffusion is controlled mainly by deprotection reaction in a low PEB temperature region [19]. In addition, several reports noted that difference of deprotection unit did not have a big impact on quantum yield of photo-acid generation [20].…”

Manipulation of Polymer Solubility: Crosslinking, Thermal Activation and Variable-Temperature Bakes

“…Our baseline 193-nm resist (described in the experimental section), is similar to other recently described open-source resists [6,12,13,17], and will function as a chemically-amplified resist by using a range of bake temperatures that are low enough to prevent PAG thermal decomposition of the PAG yet high enough to enable catalytic ester deprotection using the photogenerated acid (perfluorobutane sulfonic acid). In this step the TAG is designed to thermally decompose to generate acid, then this acid is designed to diffuse a finite distance into the overcoat and then catalyze the deprotection of the ester in that polymer.…”

“…As acid catalyzed deprotection reactions are at the heart of many DUV, 193-nm and EUV positive-tone photoresists (Figure 1A), there are many important kinetic studies in the literature. For the most part, these studies have been done in polymeric films and evaluated using FTIR [10][11][12][13][14][15][16].…”

Synthesis and evaluation of novel resist monomers and copolymers for ArF lithography: Part II

“…3) We focused on monomers with acid-cleavable protective groups, and we propose some novel monomers. 4) There were various reports about the deprotection reaction of CA positive-tone resists [5][6][7][8][9][10][11][12][13] , because the reactivity of a protective group is a factor affecting resist properties, i.e., sensitivity, dissolution behavior, resolution, and Line width roughness. However, there are few reports focused on the deprotection reactions of monomers with protective groups.…”