Dry Etching Durability Research Articles

Suppression of resist pattern collapse by crosslinker in ultraviolet nanoimprinting involving sequential infiltration synthesis with trimethylaluminum

The fabrication of resist patterns using UV nanoimprinting is required on consideration of the reduction of the use of hydrocarbons along recent amendments for environmental sustainability. In this study, we investigated the generation of resist pattern defects through UV nanoimprinting in a readily condensable trans-1,3,3,3-tetrafluoropropene (TFP) gas with a low global warming potential for elimination of nonfill defects arising from a bubble trap and subsequent sequential infiltration synthesis (SIS) to result in a vapor phase organic-inorganic hybridization for dry etching durability. A bisphenol A-based UV-curable imprint resin enabled the nanostructure fabrication of resist patterns without any nonfill defects in TFP; however, SIS consisting of subsequent mutual doses of trimethylaluminum and water caused a resist pattern collapse of 100-nm-height patterns with linewidths of <60 nm. A crosslinker with six acrylate moieties was selected based on its low TFP absorption. The crosslinker-containing imprint resin decreased the resist pattern collapse during SIS. Nanoindentation measurements suggest that the resist patterns made using the crosslinker-containing imprint resin were strengthened at 100 °C to carry out an SIS.

Healing surface roughness of lithographic nanopatterns through sub-10 nm aqueous-dispersible polymeric particles with excellent dry etch durability

Herein we demonstrate the design and use of sub-10 nm etch-durable polymeric particles for healing roughness in lithographic patterns.

Room-Temperature Nanoimprinting Using Ladder Hydrogen Silsesquioxane

Ladder hydrogen silsesquioxane (HSQ) has been proposed as a replication material to be used in nanoimprinting processes at room temperature. We replicated ladder-HSQ patterns by nanoimprinting at room temperature that were as accurate as replicated caged-HSQ patterns. Caged HSQ is the standard replication material currently used in nanoimprinting at room temperature. Caged-HSQ-imprinted patterns completely disappeared when annealed at 300 °C. However, ladder-HSQ-imprinted patterns retained almost the same rectangular profile as they had before annealing, even after being subject to high-temperature annealing at 1000 °C. Fourier transform infrared spectroscopy showed that high-temperature annealing transformed the HSQ into a SiOx structure. This vitrification of HSQ resin improved its dry-etching durability, with the dry-etching rate when subject to CHF3 reactive-ion etching decreasing from 32 to 27 nm/min, which is close to the value of 26 nm/min for thermally grown SiO2 and a quartz substrate.

48.2: The Chemical Durability of EAGLE XG™ in LCD Dry Etch Processes

AbstractThis work compared the chemical durability of EAGLE XG™, EAGLE2000™ and Code 1737 glasses in typical TFT dry etch processes. Active, dielectric, and metal films were etched with a resist mask. Glass surfaces were evaluated by dark field microscopy, SEM/EDX, and AFM. The results show dry etch durability is comparable for all three compositions.

Enhancing the dry-etch durability of photoresist masks: A review of the main approaches

A review is presented of the main approaches to the enhancement of photoresist-mask durability under dry etching. The physical and chemical processes involved are described.

Negative-Tone Polyphenol Resist using Intramolecular-Esterification Reaction for sub-50 nm Lithography

We report here a novel chemically-amplified negative-tone molecular-resist using 3M6C-MBSA-BL, which is a γ-hydroxycarboxylated polyphenol (4,4'-methylenebis[2-[di(2-methyl-4-hydroxy-5-cyclohexylphenyl)] methyl]phenol (3M6C-MBSA)) for EB and EUV lithographies to be used in hp32 and beyond technology nodes. After selection of photo acid generators (PAGs) and optimization of the concentration of PAG in the resist, we could demonstrate 40-nm line and space patterns resolution by EB exposure. The resist can make negative-tone by means of acid-catalyzed intramolecular-esterification reaction. Also dry-etching durability was confirmed. Small line-edge roughness (LER) values of 4.5 nm (inspection length: L = 620 nm) and 6.2 nm (L = 1800 nm) were achieved using the 3M6C-MBSA-BL resist.

Energy Quenching Effects on Dry-Etching Durability of Alicyclic-Aliphatic Copolymers and Polymer Blends Enhanced by Polymer-Chain Entanglement

A correlation between the macromolecular structure and dry-etching durability is essential to design a resist of high performance. Ohnishi and ring parameters are known to be useful for estimating the durability, but some limitations are apparent, since the etching rate of a multicomponent matrix polymer is not only dependent on the composition. Previously, we have demonstrated that the etching rates of copolymers and polymer blends, which are composed of fragile aliphatic monomer and stable aromatic or alicyclic monomer units, are lower (the durabilities are higher) than the values calculated from those of the constituent homopolymers with the assumed wt% additivity. In this study, we prepared methyl methacrylate [MMA]/tricyclodecanyl methacrylate [TCDMA] copolymers of various compositions, and attempted to evaluate the dependence of etching rates on TCDMA content. The dependence was found to be inconsistent with those in the cases of α-methyl-styrene, 2-vinyl-naphthalene, and isobornyl methacrylate copolymers and polymer blends reported in the previous papers.

Improvement in 193 nm Photoresists Performance by 172 nm VUV Curing

In order to make the enhancement of dry etching durability of methacrylate-based ArF resists induced by VUV curing consistent with low film shrinkage, i.e., less CD deviation, characteristics of several methacrylate-based polymers were studied. It was found that the film shrinkage mainly depended on the side chain structures and polymers containing acrylate group in main chain and norbornane lactone group in side chain portion showed dry etching resistance equal to commercially available KrF resists with lower film shrinkage than methacrylate-based ArF resists by VUV curing and suitable for the process. Curing reaction mechanism of methacrylate-based polymers were also studied using an infrared micro spectrometry with gradient shaving preparation. It was confirmed that the linkage radiolysis around carbonyl sites, mainly lactone portion of methacrylate-based ArF resist polymers induced by 15sec VUV light irradiation proceeded from the film surface to the interface with the substrate. VUV curing less than 1 minute was noticed to be effective for improvement in methacrylate-based ArF resists performance and might be met with the process tact time required for mass production phase.

P‐28: Dry‐Etching Durability of LCD Glass Substrate Against Chlorine‐Based Gas

AbstractDry etching durability of Corning EAGLE2000 and code 1737 glass substrates was compared under aluminum gate metal over‐etching conditions of chlorine based reactive ion etching. The durability upon EAGLE2000 and code 1737 was equivalent against simulated aluminum dry etching condition. The etching rates of EAGLE2000 and code 1737 were less than 1/10 of sputtered aluminum film etching rate.

Multi-adduct derivatives of C60 for electron beam nano-resists

Abstract Methanofullerenes, C 60 derivatives, work as negative type electron beam resists, which have 10-nm scale resolution and high dry-etch durability. Their sensitivity (∼10 −3 C/cm 2 ) is one order of magnitude better than that of C 60 . We studied side-chain dependence of the sensitivities of methanofullerene resists, and found that the methano bridge and >CO near the C 60 cage in the side chains play important roles in the sensitivity enhancement. We have improved the sensitivity further by synthesizing multi-adduct methanofullerene (four to six side chains), which has about two orders of magnitude higher sensitivity (3.8×10 −4 C/cm 2 ) than that of C 60 .

Improved Sensitivity of Multi-adduct Derivatives of Fullerene.

Methanofullerenes, a class of C60 derivatives, act as negative type e-beam resists with 10-nm resolution and high dry-etch durability. Their sensitivity is -10-3C/cm2, one order of magnitude better than that of C60. We studied sensitivities of methanofullerene resists by systematically changing side chains and have found that the methano bridge and >C=O in the side chains are important in the sensitivity improvement. We realized further sensitivity improvement by synthesizing methanofullerene with 4-6 side chains. This has about two orders of magnitude higher sensitivity (3.8×10-4C/cm2) than that of C60.

A triphenylene derivative as a novel negative/positive tone resist of 10 nanometer resolution

We show that a triphenylene derivative, 2,3,6,7,10,11-hexapentyl-oxytriphenylene, acts as an electron beam resist of 10-nm resolution with high dry-etch durability. The triphenylene derivative exhibited positive and negative behaviors depending on the dose and developers. When pentanol was used as a developer, positive behavior was observed for electron doses between ∼ 3 × 10 −4 and ∼ 1 × 10 −3 C/cm 2 at 20 keV, and at higher doses, the resist exhibited negative behavior. When monochlorobenzene was used as a developer, only the negative behavior was observed with a sensitivity of 2× 10 −3 C/cm 2 at 20 keV. Performance of the resists were demonstrated defining 10-nm dots and lines (negative tone), and fabricating a high aspect-ratio Si nanostructure with a single layer process.

Pattern Fabrication Technique for Ta–Ge Amorphous X-Ray Absorber on a SiC Membrane by Inductively Coupled Plasma

We developed a pattern etching method for Ta–Ge (Ta3Ge) amorphous X-ray absorbers on a SiC membrane using a mixture of Cl2 and BCl3 gases with a single-layer e-beam resist. For this work, an inductively coupled plasma (ICP) etcher with a helium back surface cooling system was used. High etching selectivity and anistropic etching were achieved by regulating electrode temperature and BCl3 concentration ratio. The etching selectivity of Ta3Ge to the resist is 6.5. Ta3Ge patterns of 0.1 µm dimensions with vertical sidewalls were fabricated. Good etching rate uniformity was also obtained over a 61-mm-diameter membrane field. We found that Ru film was a suitable etching stopper material because it has high dry-etching durability and can be easily removed by oxygen plasma etching.

A Fullerene derivative as an electron beam resist for nanolithography

We have explored the application of chemical derivatives of C60 as high-resolution electron beam resists. Facile spin coating was used to produce ∼100-nm-thick films of a C60 tris adduct (three functional groups) on Si surfaces. We find that these films function as high-resolution negative resists for electron beam lithography using monochlorobenzene as a developer. The film has a sensitivity of ∼1 mC/cm2 for 20 keV electrons, an order of magnitude higher than that of C60 itself, and the dry-etch durability is much better than that of conventional novolac based electron beam resists. Features with widths of 20 nm were produced.

Energy Quenching Effects on Dry-Etching Durability of Copolymers and Polymer Blends of Vinylnaphthalene or α-Methyl Styrene with Methyl Methacrylate

Durabilities for O2 reactive ion etching (O2RIE) were studied as a function of number-average molecular weight (Mn) of poly(methyl methacrylate) [PMMA], poly(α-methyl styrene) [PMSt] and poly(2-vinylnaphthalene) [PVN]. Etching rates were independent of the Mn and in the descending order of PMMA, PMSt and PVN. Dry-etching durability which was defined as the reciprocal of etching rate relative to PMMA, of PVN was higher than that of PMSt. 2-Vinylnaphthalene (VN) moiety was found to be more effective for enhancing dry-etching durability than α-methyl styrene (MSt). Dry etching durabilities of copolymers (PMMA-co-MSt, PMMA-co-VN) were equal to those of polymer blends (PMMA/PMSt, PMMA/PVN) of the same composition and larger than the values calculated from the constituent homopolymers assuming the wt% or vol% additivity as the estimated bombardment probability by ion and neutral active species.

Functionalization of Fullerene for Electron Beam Nanolithography Resist.

We have found that chemical modification of C60 to the methanofullerenes improves the properties as an electron beam resist. Several types of methanofullerenes exhibit good resolution and high dry-etch durability, and the films can he prepared by spin coating. Thus they can be used for nanometer scale patterning. The sensitivity is -1×10-3C/cm2, an order of magnitude higher than that of C60. The performance of the resists was demonstrated by defining 20nm features. The results of Raman measurements suggest that the exposure mechanism may be due to destruction of the C60 cage by electron irradiation.We have shown that the chemical modification of C60 molecules dramatically improves the properties as a negative e-beam resist. The methanofullerene resists can be prepared by spin coating and their sensitivity is -10-3C/cm2, an order of magnitude higher than C60 itself. These resists exhibit good resolution and high dry-etch durability. The performance of this resist was demonstrated by defining 20nm lines. It was also shown that the exposure mechanism seems to be the fragmentation by e-beam irradiation.

Nanolithography Using Fullerene Films as an Electron Beam Resist.

Nanometer scale patterns have been fabricated using evaporated films of C60 and its derivative, C60(CH2)2(C10H6), as negative type electron beam (e-be am) resists. E-beam irradiation reduces the dissolution rate of the films in organic solvents such as monochlorobenzene. In addition, the rate of thermal sublimation in vacuum is also reduced by the exposure. These molecules have quite similar resist properties. They exhibits good resolution and high dry-etch durability. The performance of the resists was demonstrated by defining about 20nm dot patterns in the resist films and fabricating Si nanopillars, about 20nm in diameter and 100nm high, by subsequent plasma etching. The results of optical measurements suggest that the exposure mechanism of C60 resist may be due to destruction of the molecules by e-beam irradiation.

ArF surface modification resist process with enhanced water sorption ability

Surface modification resist (SMR) process, which gives negative-tone image owing to the polysiloxane formation in the exposed resist surface using chemical vapor deposition, was studied for subquarter micron pattern fabrication. SMR was based on the hydrolysis of alkoxysilane and the subsequent condensation reaction in the presence of an acid catalyst and water. This article describes the application of SMR to ArF excimer laser lithography with enhanced water sorption ability. We propose the copolymer of propylideneimino p-styrenesulfonate (PPISS) and methyl methacrylate with enhanced water sorption ability in order to improve the selectivity of the polysiloxane formation. PPISS generates sulfonic acid and acetone which acts as the diffusion promoter of water molecules. It was demonstrated that the hydrolysis reaction was promoted and the polysiloxane was more selectively formed with high sensitivity by using the proposed polymer. The influence of PPISS units ratio for the selectivity of polysiloxane formation and dry etch durability was investigated. Below 0.2 μm patterns fabrication was demonstrated by optimizing the ratio of the PPISS unit which functioned as the selective generation of acid and acetone.

Sensitivity-enhanced dry development process for VUV and EUV lithography using graft-polymerization

The proposed dry development process uses the graft-polymerization of Si-containing monomers to silylate the resist surface, thus enhancing oxygen plasma etching durability. Single-layer and negative-tone resist patterns can thus be delineated with very high sensitivity. Grafting sensitivity higher than that of wet-developed chemical-amplification resist is obtained by using a Si-containing monomer having acrylic acid ester. This is confirmed through experiments using PMMA as the resist, 3-acryloxypropylmethyldimethoxysilane (APMS) as the monomer, and a laser-plasma X-ray source for exposure. The dry-etching durability of PMMA grafted using APMS is about four times that of ungrafted PMMA. FT-IR measurements show that this is due to the resist-surface silylation caused by the grafting. These results indicate the applicability of this process to VUV and EUV lithographies.

Development of single‐layer positive resist process for electron beam direct writing technology

AbstractA single‐layer resist process using a high resistivity positive resist by solubility reversal (PSR) for electron beam direct writing is described. Conventional PSR designed for mask creation is found to have inhomogeneous dissolution characteristics due to a side effect during the stage of deprotection reaction. To overcome this problem, the efficiency of dissolution inhibition is improved by controlling the composition of base resin materials. Using an optimized base resin structure, 0.4‐μm contact window patterns were successfully delineated in a 1.6‐μm thick single‐layer with a sensitivity of 3.5 μC/cm2. The dry etching durability of a single‐layer PSR was also examined and a high level of dry etching durability for SiO2 etching was observed.