A simple method to calculate incident dose for the proximity effect correction

A simple method for correcting the proximity effect (PEC) is demonstrated. By modifying the discretized point spread function (PSF), the incident dose is expressed as a function of the ideal deposition energy density, the backscattering energy and the center energy fraction of the PSF matrix. The optimum incident dose can thus be solved iteratively. Then, the constraint to the iterative equation is discussed and the allowed value range of the center energy fraction in the discretized PSF is calculated under the different pattern densities. The correcting result is finally experimental verified. Results showed the line width deviation from the mean is decreased from the maximum of 0.01 μ. to that of below 0.003 μ.m after the PEC applied. The improved critical dimension (CD) uniformity indicating a uniformity energy distribution is achieved by this method.