A completely new concept for designing the illumination aperture filter is suggested. From experimental or simulative methods, we have extracted the performance of every individual beam component on the illumination plane. The optimal apertures are then obtained by superimposing the best components that meet the requirements demanded by the specific photo processes. Different kinds of optimal apertures were successfully implanted to deal with different process problems. Therefore, it is called the customized illumination aperture filter (CIF). The zero 1D OPE CIF, as a proof of concept, was designed to eliminate the OPE of low k process. Without any OPC, O.6.tm DOF ofthe common ED window was obtained, where ki 0.39 for our NA0.55 stepper to print 0. 18.tm line patterns. To push to smaller ki, another CIF was designed to maximize the individual DOF and overcome the reduced power problem accompanied with the typical aggressive OAI.Using this CIF, we achieved I . Im common DOF with 7% EL for 0. 1 8.tm line patterns. The CIF doubles the power of the Nikon's strong quadrupole, shrinc. An ultimate resolution limit of 0. 1 1.tm line pattern was reached as well with the CIF. Finally, a contact/via CIF was designed combined with a half-tone PSM (6%). The CIF gives about O.8im common DOF with 7% EL for O.2.tm holes and O.7.tm DOF for 0. l7prn holes using thinner resist. The CIF approach is, therefore, proven to be a cost effective and relatively easy realizable alternative to the alternating PSM for extremely low ki process applications.

Abstract. This letter reports record-breaking low defect counts for immersion lithography, the mechanism for formation of particle-printing defects, and for two new exposure routings to achieve the low defect counts. Both new routings make the slot-scan directions parallel to the field-stepping directions, whereas in the normal routing the two directions are perpendicular to each other. From experimental data, the average defect count for one of the special routings is 4.8 per wafer, while it is 19.7 per wafer for normal routing.

This paper reports the water-leakage mechanism of the immersion hood in an immersion scanner. The proposed static analysis reveals the immersion hood design performance in defect distribution. A dynamic water-leakage model traces the leaked water and identifies its position on the wafer, during exposure. Comparing simulation to experimental results on bare-silicon and resist-coated wafers, the defect type, source of residuals, and critical settings on the immersion system were clearly identified. 1.INTRODUCTIONImmersion lithography is the only viable choice to produce 65-nm and 45-nm half-pitch circuits. Although 193-nm immersion lithography is being developed at an unprecedented pace, it still needs enormous efforts to meet the extremely tight requirements for the 45-nm node. 1,2,3 One of them is defect density. It needs to be as low as 1 defect per wafer pass, especially when many device layers are exposed with immersion scanners.The immersion hood (IH) is an important component of the immersion scanner for supplying, confining, and draining the water during exposure. Unfortunately, the fluid will leak from the IH due to insufficient constrain and the droplets left will produce watermark defects. Besides watermarks, the liquid coupling medium is more likely to carry particulates than the air coupling medium, no matter these particles are from materials, the wafer, or the exposure system itself. The particulates may be left through water leaking from the IH during wafer movement and cause printing and fall-on defects.Hence, preventing water leakage is one of the most critical issues for immersion defect reduction. This paper reports a static residuals analysis to monitor the IH design performance and define the correlation between airflow instability and water leakage in the IH. Furthermore, a dynamic water-leakage model has been setup, basing on the mechanism discussed in Section 3. This dynamic model traces the water-leakage trajectory during exposure routing.

193-nm immersion lithography is the only choice for the 45-nm logical node at 120-nm half pitch and extendable to 32-and 22-nm nodes. The defect problem is one of the critical issues in immersion technology. In this paper, we provided a methodology to trace the defect source from optical microscope images to its SEM counterparts after exposure. An optimized exposure routing was also proposed to reduce printing defects. The average defect count was reduced from 19.7 to 4.8 ea/wafer.

A simple graphic analysis technique named the illumination chart method is introduced to aid the customization of the illumination aperture filter for synergistic combination with a high transmission rimtype attenuated phase-shifting mask (PSM) for deep submicron contact hole printing. This graphic method gives direct visualization of the relationship between the interference condition in the pupil and the incident angle of illumination. The working ranges of oblique illuminations with different numbers of diffraction beams taking part in imaging can be easily clarified by this graphic method, which explains the dependence of depth of focus (DOF) on pattern duty. A customized illumination aperture filter (CIF) is synthesized by collecting the effective source elements for every pattern pitch to remedy the inability of the attenuated PSM for dense patterns. To preserve the merits of off-axis illumination to dense patterns and on-axis illuminations to sparse patterns in a single exposure, the illumination chart suggests a zeroth-order-reduction mask design for dense hole pattern. We applied this integrated resolution enhancement technique to 0.17 m contact hole printing in 248 nm wavelength, 0.55 numerical aperture optics. The experimental results show our CIF illumination not only balances the DOF enhancement throughout the pattern pitches but also suppresses the best focus shift due to spherical aberration. © 2002 Society of Photo-Optical Instrumentation Engineers.