Advanced Processes for 193-nm Immersion Lithography

Abstract

One unique aspect of 193i lithography is the use of water situated between the final lens element and the resist. The resist stack (with or without topcoat) on the wafer is dynamically exposed through this water with the step-and-scan process. The photoacid generator (PAG), quencher, and other small molecular components of the resist may leach into this water. These leached components contaminate the water and may degrade resist performance. This contaminated water can additionally contaminate the lens and wafer stage of the scanner. To master these leaching problems, we must understand the dynamics of resist leaching, transportation of leached contaminates in the immersion water, and the impact of these contaminants on the lens during exposure.Additionally, water can penetrate the topcoat and diffuse into the resist film. This penetration and diffusion of water can cause the topcoat or the resist to swell, which will affect their lithographic performance. This chapter specifically addresses the following issues: (1) leaching test methods, (2) leaching dynamics, (3) leaching with 193-nm exposure, (4) pre-rinse to partially remove leached contaminants, (5) lens contamination caused by resist leaching, and (6) water uptake in resist film.

Secondary Electrons in EUV Lithography

“…One of the key differences between traditional photolithography and EUV is the fundamental mechanism by which photons used in these imaging technologies interact with matter. At conventional wavelengths (365, 248, and 193 nm), a photon promotes an electron in a chromophore within the resist from a bonding to an anti-bonding orbital, which causes these molecules to decompose and produce acid [1,2].…”

Anti-aliased Euclidean distance transform

“…Such sub-pixel erosion and dilation of anti-aliased images are useful for e.g. digital photolithography, where there is a need to compensate for imperfections in the exposure and etching process which yield an erosion or dilation of the final outlines (Wei and Brainard, 2009). Level sets created from DT images with our method will be more accurate, in particular near the edge, even from lower resolution input data.…”

The new method of fabrication of submicron structures by optical lithography with mask shifting and mask rotation

“…Other approaches to increase pattern resolution, without changing the lithographic system optics, are double patterning lithography (DPL) [5] and double exposure lithography (DEL) [6]. DPL and DEL are well described in the literature as methods that make it possible to increase the number of structures per square [3]. In the article, both techniques were presented.…”

“…The application of shorter wavelengths is connected with increased cost and system complexity. For this reason, mixed techniques, like immersion lithography [3] or special phase-shift masks [4], are used. Such combined methods enable higher resolution production while using well-known UV lithographic equipment.…”