This paper discusses the current performance and the evolution of five generations TWINSCAN immersion scanning exposure tools. It is shown that production worthy overlay and focus performance can be achieved at high scan speeds. The more critical part for immersion tools is related to defects, but also here improvements resulted in production worthy defect levels. In order to keep the defect level stable special measures are needed in the application of wafers. Especially Edge Bead Removal (EBR) design and wafer bevel cleanliness are important.

A new purged UV spectroscopic ellipsometer to characterize thin films and multilayers at 157 nm AIP Conf.Immersion lithography has recently emerged as the preferred lithography solution for manufacturing the next generation of semiconductor devices (likely to address the 65, 45, and possibly the 32 nm nodes). Full-field immersion scanners operating at = 193 nm with de-ionized water as the immersion fluid have been recently demonstrated. In this article we report imaging results from the AT1150i prototype, a 0.75 numerical-aperture full-field scanner from ASML. We experimentally confirm the depth-of-focus improvements that immersion enables, and explore the implications of this gain for semiconductor manufacturing. This article also highlights the challenges the technology faces before it can be successfully introduced for semiconductor manufacturing. We pay particular attention to defects, in the form of particles, bubbles, and other processing residues, and highlight evaporation as a key mechanism underpinning these challenges.

As the semiconductor industry looks to the future to extend manufacturing beyond 100nm, ASML have developed a new implementation of an old optical method for lithography. Immersion lithography can support the aggressive industry roadmap and offers the ability to manufacture semiconductor devices at a low k1.In order to make immersion lithography a production worthy technology a number of challenges have to be overcome. This paper provides the results of our feasibility study on immersion lithography. We show through experimental and theoretical evaluation that we can overcome the critical concerns related to immersion lithography. We show results from liquid containment tests focussing on its effects on the scan speed of the system and the formation of microbubbles in the fluid. We present fluid-to-resist compatibility tests on resolution, using a custom-built interference setup. Ultimate resolution is tested using a home build 2 beam interference setup. ASML built a prototype full field scanning exposure system based on the dual stage TWINSCAN TM platform. It features a full field 0.75 NA refractive projection lens. We present experimental data on imaging and overlay.keywords: immersion lithography, high NA, TWINSCAN, bath, shower 1.INTRODUCTIONFor more than 25 years the semiconductor industry has predicted the end of optical lithography. Recent developments, however, show us that optical lithography is more alive than ever before. Immersion lithography has emerged as the potential technology for extending optical lithography. Immersion lithography makes use of fluids with refractive indexes that are greater than 1.0 (the refractive index of air) to enable the use of lenses that have Numerical Apertures (NAs) larger than 1.0. Immersion, in principle, is not a new technique. Its viability for microlithography, however, has become a practical consideration because of advances made in lens manufacturing technology, especially a-spherical surface figuring. For 193-nm lithography, water proves to be a suitable immersion fluid. The refractive index for water is 1.43, which makes lens NAs above 1.2 feasible. Immersion offers the potential to extend conventional optical lithography to the 45-nm node and even potentially to the 32-nm node. The main challenges for deployment of immersion are in the design of the exposure tool. Early work done by International Sematech shows that existing photo resists can be compatibility with immersion. However, further work is required in this area.In this paper we discuss the achievements of both exposure tool design and the interaction between existing photoresists and immersion fluids. Section 2 provides the results of our feasibility study on immersion lithography. Section 3 shows the results of our prototype TWINSCAN TM immersion scanner, and finally section 4 summarizes the conclusions of this paper.

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Defectivity has been one of the largest unknowns in immersion lithography. It is critical to understand if there are any immersion specific defect modes, and if so, what their underlying mechanisms are. Through this understanding, any identified defect modes can be reduced or eliminated to help advance immersion lithography to high yield manufacturing. Since February 2005, an ASML XT:1250Di immersion scanner has been operational at IMEC. A joint program was established to understand immersion defectivity by bringing together expertise from IMEC, ASML, resist vendors, IC manufactures, TEL, and KLA-Tencor. This paper will cover the results from these efforts.The new immersion specific defect modes that will be discussed are air bubbles in the immersion fluid, water marks, wafer edge film peeling, and particle transport. As part of the effort to understand the parameters that drive these defects, IMEC has also developed novel techniques for characterizing resist leaching and water uptake. The findings of our investigations into each immersion specific defect mechanism and their influencing factors will be given in this paper, and an attempt will be made to provide recommendations for a process space to operate in to limit these defects.

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