KrF excimer laser lithography with a phase‐shifting mask for gigabit‐scale ultra large scale integration
| Autor: | Toshihiko P. Tanaka, Akira Imai, Tsuneo Terasawa, Naoko Asai, Shinji Okazaki, Norio Hasegawa |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Dynamic random-access memory
Materials science Excimer laser Aperture business.industry medicine.medical_treatment General Engineering Atomic and Molecular Physics and Optics law.invention Light intensity Optics law medicine Optoelectronics Photolithography Photomask business Phase shift module Lithography |
| Zdroj: | Optical Engineering. 35:2970 |
| ISSN: | 0091-3286 |
| DOI: | 10.1117/1.600980 |
| Popis: | Resolution-enhancement technologies such as alternatingtype phase-shifting masks (PSMs), half-tone PSMs, and the off-axis illumination method in optical lithography are necessary for manufacturing gigabit-scale ultra large scale integration (ULSI) devices. Because an alternating-type PSM is the most effective way to enhance resolution, we examine the resolution capabilities of KrF excimer laser lithography combined with the use of an alternating-type PSM through simulations. Our goal is to apply this technique to attain pattern delineation smaller than 200 nm. We simulate light intensity profiles for various types of PSMs in terms of the 3-D mask structure, and find that a PSM structure with a spin-on glass (SOG) phase shifter on a Cr layer that is thinner than in a conventional mask is one of the best choices for KrF excimer laser lithography. We examine potential problems such as the durability of the SOG phase shifters to KrF excimer laser irradiation exposure, and phase angle error due to the surface topography of the Cr aperture patterns. From our experimental results, we confirm that the optical characteristics of the PSM are not degraded, and the phase angle can be controlled with an accuracy sufficient for gigabit-scale ULSI device fabrication. Improved PSMs with a thin Cr layer and SOG phase shifters were successfully used to fabricate several layers of experimental 1-Gbit dynamic random access memory (DRAM) devices with sufficient resolution capability. |
| Databáze: | OpenAIRE |
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