20 August 1986 Practical I-Line Lithography
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The continual push of the semiconductor industry to achieve higher density devices has placed tremendous demands on lithography. Several techniques have been used to achieve submicron feature sizes including multilayer resists, larger numerical aperture stepper lenses, and e-beam and X-ray exposure tools. Each of these approaches has been shown to have unique problems that limit its application in production processing. With the recent availability of large image field wafer steppers utilizing the 365 nanometer mercury emission line, optical lithography may now routinely achieve features on the order of 0.8 micron and below. This paper presents data on the practical application of a 10X i-line wafer stepper to VLSI and ULSI device fabrication. Performance data on a production worthy 0.8 micron single layer resist process are discussed. With i-line lithography important differences in the response of conventional photoresists have been observed. Because of the increased absorbance of the resist at i-line as compared to g-line, attenuation of the incident light reduces adverse reflection effects to give excellent linewidth control over topography even on highly reflective surfaces. The differences in resist absorption for g-line and i-line and the effects of absorption of i-line radiation on resist profiles is shown for several commercially available resists. Use of a multilayer resist system has allowed for the extension of the resolution to 0.5 micron. In contrast to previous i-line steppers useful primarily in laboratory and prototype operations, recent advances by equipment suppliers coupled with conventional or multilayer resist processing now provide a production worthy submicron lithography system for high volume semiconductor manufacturing.
© (1986) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Mike Tipton, Vic Marriott, Gene Fuller, "Practical I-Line Lithography", Proc. SPIE 0633, Optical Microlithography V, (20 August 1986); doi: 10.1117/12.963699; https://doi.org/10.1117/12.963699

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