In near-field scanning optical microscopy, a light source or detector with dimensions less than the wavelength (lambda) is placed in close proximity (lambda/50) to a sample to generate images with resolution better than the diffraction limit. A near-field probe has been developed that yields a resolution of approximately 12 nm ( approximately lambda/43) and signals approximately 10(4)- to 10(6)-fold larger than those reported previously. In addition, image contrast is demonstrated to be highly polarization dependent. With these probes, near-field microscopy appears poised to fulfill its promise by combining the power of optical characterization methods with nanometric spatial resolution.

In this work we demonstrate the power, speed and effectiveness of an automated rules-based approach for performing optical proximity correction. The approach applies to both conventional and phase-shifting mask layouts for optical lithography. Complex imaging, substrate and process phenomena can be folded into comparatively few rules parameters. Using simple arithmetic, these parameters pre-compensate the layout for the combined proximity effects. The rules consist of edge rules and corner rules for biasing feature edges and for adding sub-resolution assist features. This paper describes an integrated solution which includes rules parameter generation and fast, hierarchical rules application. Experimental results demonstrate improved edge placements and wider process latitude than for non-corrected layouts.

While off-axis illumination has been demonstrated to improve contrast and depth of focus for low k1, packed line–space (L/S) patterns [S. Asai, I. Hanyu, and K. Hikosaka, J. Vac. Sci. Technol. B 9, 2788 (1991); K. Kamon et al., Jpn. Appl. Phys. 30, 3021 (1991); K. Tounai et al., Proc. SPIE 1674, 753 (1992)], application of this approach to the more discordant patternings associated with random logic levels is suspect. We introduce a conventional mask ‘‘assist’’ feature technique that extends the off-axis L/S enhancements to more isolated features (both spaces and lines). It will be shown that the effective process window is substantially improved and exhibited proximity effects are mitigated for this technique. Also, a comparison to a phase-shifting mask solution for the patterning mix expected in random logic layouts is performed. Simulation results are verified on a 0.53 NA, DUV stepper.

Exposure characteristics of an alternate aperture phase-shifting mask fabricated using a subtractive process will be discussed. The subtractive process, where the phase-shifted regions are etched into a layer below the chromium, is attractive because it allows for the use of conventional chromium-an-quartz blanks, as well as providing more processing flexibility, However, recent results using a subtractive fabrication process have determined that a linewidth variation of -0.05 f..lm exists between features imaged with etched and nonetched regions of the alternate aperture pattern. This article examines some of the potential causes for this linewidth variation, including mask linewidth control, surface roughness, contamination during phase-shift forming etch step, and sidewall profile and position. Results indicate that the sidewall profile and position are critical parameters in defining the wafer feature size. The impact of phase is also investigated. The wafer feature size depends on the depth of the quartz etch and accurate endpointing of the phase-shift depth is essential for maintaining critical dimension uniformity across an features imaged with a phase-shifting mask.

A multilayer inorganic antireflective system for use in 248 nm deep ultraviolet lithography Plasmask(R) resist and its associated dry development process called DESIRE constitute one product which has incorporated surface imaging for lithography at 436 and 366 nm. Based on its performance at these wavelengths, Plasmask® 150U resist is predicted to have a resolution limit of -0.3 pm at 248 nm with a 0.38 NA lens. Using best focus exposures of 1.5-pm thick films we have examined a variety of factors that influence the resolution and sensitivity of Plasmask® 150U resist at 248 nm. These include standard processing steps as well as silylation with hexmethyldisilazane, plasma development conditions and equipment, and various descum techniques. Processing without a descum step resolved 75° profile, 0.3 pm line and space patterns at high exposure doses, but always afforded a grassy residue. Use of Ar sputter etching to remove -2200 A from unexposed areas prior to plasma development afforded vertical profile O.3-pm resolution patterns with no grassy residue.