26 May 1995 Impact of optical thin film effects on CD control in DUV lithography
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We examine the effects of optical thin films on CD control in DUV lithography. A number of different substrates typical of device lithography levels were fabricated. Film stack configurations were chosen for their optical properties as well as process integration compatibility. All wafers were then exposed with an open field to measure swing amplitude, followed by a resolution test pattern to measure proximity effect and dose latitude. The resolution test pattern consisted of 250 nm coded features varying in pitch from 500 to 1750 nm. Results will be presented for optimum CD control over four types of film stacks as a function of resist thickness. In general, it is always best to operate at an extremum of the swing curve in resist thickness. However, the underlying film stack effects the CD control differently at Emin versus Emax. We present the optimum exposure conditions for a number of film stacks, resist thickness, and types of illumination (conventional and annular). These results were corroborated by optical imaging software enhanced to incorporate resist thickness and thin film effects. A synopsis of the role of substrate optical properties on CD control will be presented.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Raymond A. Cirelli, Raymond A. Cirelli, Joseph G. Garofalo, Joseph G. Garofalo, Eric L. Raab, Eric L. Raab, Jiabei Xiao, Jiabei Xiao, Robert John Socha, Robert John Socha, Sheila Vaidya, Sheila Vaidya, } "Impact of optical thin film effects on CD control in DUV lithography", Proc. SPIE 2440, Optical/Laser Microlithography VIII, (26 May 1995); doi: 10.1117/12.209289; https://doi.org/10.1117/12.209289

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