3D proximity effect correction based on the simplified electron energy flux Model in electron-beam lithography

摘要

We have confirmed the adequacy of simplified electron energy flux (SEEF) model which can be used in proximity effect correction (PEC) in electron beam lithography. The SEEF model enables calculation of the backscattering energy in a multiwiring structure by obtaining a transmission and reflection energy flux map. We prepared a substrate which contained three pairs of W-plug layers and inter-metal dielectric (IMD) layers, and obtained parameters for correction. The extracted transmittance and reflectance were 1 and 0 for the dielectrics; and 0 and 1.7 for the W plugs. The backscattering energies calculated by using these parameters corresponded with experimental data under the various conditions. We also extracted the scattering range of incident and reflected electrons in dielectrics. We found that the ranges of the reflected electrons were greater than those of the incident electrons because of a wider spread of angle. PEC based on the SEEF model enabled high CD accuracy even at the end of the W-plug area. We thus confirmed that the SEEF model can accommodate complex effects, such as scattering in a multiwiring structure or the screening effect, by following the electron's path.