26 March 2008 Characterization of array CD uniformity with respect to pattern density in 193nm dry photolithography
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As we move toward printing sub-100nm features using 193nm dry photolithography with high-contrast photoresists, effects of mask transmission and pattern density start to play an important role in critical dimension uniformity (CDU). With these two factors in existence, the linewidth for a dense feature block gradually increases from the center to the edge of the array of the block. This change in CD is typically observed for low-transmission reticles. In this paper, we have characterized variables, such as reticle tone and resist processing parameters, which have an effect on the CD uniformity. Use of high-contrast photoresist can increase the effect of chemical flare and can have higher CDU. We have further shown that by using a topcoat or by making changes in the resist bake temperature and time, the effect of chemical flare can be reduced. We also propose a mechanism by which resists exhibit this characteristic and show that both the photoacid generator and quencher can contribute to chemical flare.
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Vishal Sipani, Vishal Sipani, David A. Kewley, David A. Kewley, Kaveri Jain, Kaveri Jain, Erik R. Byers, Erik R. Byers, Bruce Daybell, Bruce Daybell, Anthony Krauth, Anthony Krauth, "Characterization of array CD uniformity with respect to pattern density in 193nm dry photolithography", Proc. SPIE 6923, Advances in Resist Materials and Processing Technology XXV, 69233O (26 March 2008); doi: 10.1117/12.773316; https://doi.org/10.1117/12.773316

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