Chromeless phase lithography using scattering bars and zebra patterns

Abstract

Resolution enhancement technology refers to a technique that extends the usable resolution of an imaging system without decreasing the wavelength of light or increasing the numerical aperture (NA) of the imaging tool. Off-axis illumination and a phase shift mask (PSM) are essentially accompanied by optical proximity correction (OPC) for most devices nowadays. Chromeless phase lithography (CPL) is one of the PSM technologies. To obtain the best resolution, proper OPC is required with CPL. While the most common application of OPC is to provide mask bias, an additional technique is the use of scattering bars (SBs) and zebra patterns. We compared zebra patterns for 65 nm lines and spaces (L/S) and 45 nin isolated line (I/L) with Sl3s. To optimize zebra pattern density, we vary the line width and pitch of the zebra patterns. We confirmed that the use of SB and zebra patterns could realize the target linewidth and control necessary for acheiving dense L/S and I/L.