Coulomb Interaction Effect Correction in Electron-Beam Block Exposure Lithography

A new proximity effect correction technique for variably shaped beam and block exposure tools capable of correcting pattern size variations due to the Coulomb interaction effect is proposed. The Coulomb interaction affects the forward scattering term of a double-Gaussian energy intensity distribution. The double-Gaussian energy intensity distribution function is modified so that the forward scattering term has an electron-beam current dependency. The relationship between the electron-beam current and electron-beam blur is determined by a knife-edge electron-beam profile measurement. Experiments show that the relationship between the electron-beam blur and the current can be roughly approximated by a linear function of the electron-beam current below 1.5 µA. This relationship is applied to the double-Gaussian-based proximity effect correction program. Successful correction is demonstrated for 0.13 µm L/S test patterns.