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1 July 1991 Use of antireflective coatings in deep-UV lithography
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This paper discusses issues concerning the use of a thin absorbing organic anti-reflective (AR) coating for 0.5 micrometers excimer laser lithography. Linewidth profiles, CD control, substrate dependence and etching are all affected by the presence of the AR coating. The advantages of implementing highly absorbing organic AR coatings are that CD control with resist thickness (swing curve) is improved, substrate reflectivity effects becomes negligible, adhesion is improved and reflective notching is decreased, leading to better CD control over topography. For example, the swing curve was reduced from 0.18 micrometers to 0.04 micrometers by using an absorbing AR film. Exposure/focus latitudes were modeled using Obelisk software. This gave an exposure dose of 26 mJ/cm2 for printing 0.5 micrometers dense lines on aluminum, poly- silicon, oxide, nitride and tungsten. In addition, the exposure latitudes for these substrates was found to be +/- 10% when the total depth of focus was 1.2 micrometers . Statistically designed experiments were used to optimize resist profiles of the SNR248 resist images on AR coating. Issues relating to implementing organic AR coatings under a 1300 angstrom absorbing AR coating reduced reflectivity variation on poly-silicon from 38% to 6% over a resist thickness range of 350 angstrom. By using the AR coating the swing curve variation was reduced from 0.18 micrometers to 0.04 micrometers .
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Satyendra S. Sethi, Romelia G. Distasio, David H. Ziger, James E. Lamb III, and Tony D. Flaim "Use of antireflective coatings in deep-UV lithography", Proc. SPIE 1463, Optical/Laser Microlithography IV, (1 July 1991);

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