Full field analysis of lithography performance for ArF immersion lithography

Full field analysis of pattern displacement caused by lens aberrations for ArF immersion lithography is presented for the critical dimension (CD) of the 65 nm node. Pattern displacement (PD) is the most critical issue for lithography performance if the CD uniformity is constrained within ΔCD<±10% CD and the depth of focus is larger than 0.4 μm. In-house MicroCruiser software was developed and generated mass groups of 36 Zernike coefficients with certain root mean square of wave-front error (rms WFE) and peak-to-valley value of WFE in order to study the cross talk between different Zernike coefficients. MicroCruiser communicated with PROLITH 8.0 commercial software and processed mass data automatically. The mass results of lithography performance were completed under different conditions of lens aberrations, mask types, and exposure-tool settings at each field point. The results show that with the same rms WFE, the PD will be larger if an alternate phase-shifting mask and conventional illumination are employed as compared the PD if a binary mask and annular illumination are used. For the impact of aberrations on imaging performance, the cross talk between different Zernike coefficients is more essential than a mere rms WFE.