Analysis of dose modulation method for fogging effect correction at 50-KeV e-beam system

In this paper, the influence of dose modulation on CD trend by using electron beam exposure model has been investigated and simulated. To predict CD trend, we developed an analysis program, which shows the exposed energy profile and the corrected CD distribution in mask. First, it calculates the factor of fogging effect correction ( D f ) from pattern density distribution with the assumption that fogging effect depends on only pattern density. And then it calculates the modified dose for correcting both proximity and fogging effect. From dose distribution, the corrected CD is calculated analytically by using e-beam lithography model: see Figure 1. It can give a glance how the dose modulation method has an influence on the CD uniformity. Moreover, the result of global error correction such as side, radial error at the mask writing stage has been analyzed in this study.