The quencher mechanisms in Chemically-Amplified (CA) resists have been investigated. To explain the acid distribution with a variety of acid strengths in the presence of quencher, a new full Acid-Equilibrium-Quencher model (AEQ model) is proposed and examined in solid-model-CA-resist systems. To observe the reactions in the CA resists, real-time Fourier-Transform-Infrared Spectroscopy (FTIR) is employed during post-exposure bake (PEB). The FTIR peaks of the protection groups are detected to measure the reaction kinetics during PEB. The solid-model-CA resists used in this work consist of both a KrF-acetal-type resist with a diazomethane Photo-Acid Generator (PAG) (weaker-photoacid system) and an ArF-ester-type resist with a sulfonium-salt PAG (stronger-photoacid system). The obtained FTIR results are analyzed using conventional Full-Dissociation-Quencher model (FDQ model) and the new AEQ model. The kinetic analysis of the model resists was performed for different quencher loadings. For the weaker-photoacid system, the AEQ model much more accurately predicts the deprotection-reaction kinetics than the FDQ model with the change of quencher content. This suggests the necessity of introduction of the acid-dissociation concept in the case of the weaker photoacid. For the stronger-photoacid system, both the AEQ and conventional FDQ models adequately predict the kinetic results. This shows that the conventional FDQ model is accurate enough to simulate the super-strong photoacid system. Finally, the new AEQ model is introduced in the UC Berkeley STORM resist simulator. Some simulation examples are shown in the paper.
Recently 193 nm immersion lithography is considered the most promising next generation technology which will enable a 45 nm and below node device to be manufactured. This will lead to not only depth of focus (DOF) enlargement, but immersion lithography enables the use of a hyper numerical aperture (NA) larger than 1.0 and achieve higher resolution capability. For 193 nm lithography, water is an ideal immersion fluid, providing suitable refractive index and transmission properties. Furthermore the higher refractive index fluid is expected to provide a potential extension of optical lithography to the 32 nm node. This paper describes the critical issues of the water immersion lithography process, such as photoresist component leaching into water, defectivity etc. Leaching materials were analyzed by liquid chromatography‐mass spectrometry (LC‐MS) and were found to be composed of the photoacid generator (PAG) and its decomposed chemicals. The leaching amount is in the order of 10−12 mol/cm2 with a normal 193 nm photoresist. An other issue to be studied is the water‐mark defect caused by small waters droplets left on the exposed wafer. These undesirable phenomenons could be prevented by applying a topcoat material onto the photoresist film. Material design for the topcoat material and its physical and lithographic properties are discussed in detail. Development of a high refractive index fluid is also discussed in this paper. A promising high refractive index fluid HIL‐001 was developed which has a higher refractive index (n = 1.64) than water and high transparency (98%/mm) at 193 nm wavelength. Immersion exposure experiments using high refractive index fluid with and without topcoat material was carried out and 32 nm L/S imaging capability was demonstrated by using a two‐beam interferometric exposure tool. Copyright © 2006 John Wiley & Sons, Ltd.
ArF immersion lithography using a high-refractive-index fluid (HIF) is considered to be a promising candidate for the 32nm node or below. At SPIE 2005 we introduced a new immersion fluid, JSR HIL-1 ¶ , which has a refractive index and transmittance of 1.64 and >98%/mm (193.4nm, 23 o C), respectively [3] . With HIL-1 immersion and a two beam interferometric exposure tool, hp32nm L/S imaging has been demonstrated. In this paper, we will report another novel immersion fluid, HIL-2, which has a transmittance of >99%/mm, which is almost as high as that of water, and a refractive index of 1. 65 (193.4nm, 23 o C). Furthermore, an ArF laser irradiation study has shown that the degree of photodecomposition for both HIL-1 and HIL-2 is small enough for immersion lithography application. A "fluid puddle" defect study confirmed that HILs have less tendency to form immersion-specific photoresist defects and the refractive indices of HILs were found constant under laser irradiation. Batch-to-batch variation in refractive index during manufacture of HILs was not observed. By refining prism designs, hp30nm L/S patterns have also been successfully imaged with two interferometric exposure tools and HIL immersion.
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