Thermal Effect Induced Wafer Deformation in High Energy E-Beam Lithography

The incident surface power density in Massive Electron-beam Direct Write (MEBDW) during exposure is similar to 105 W/cm(2), much higher than similar to 8 W/cm(2) ArF scanners and 2.4 W/cm(2) EUV. In addition, the wafer's exposure in vacuum environment makes energy dissipation even harder. This thermal effect can cause mechanical distortion of the wafer during exposure and have has a direct influence on pattern placement error and image blur. In this paper, the thermo mechanical distortions caused by wafer heating for MEB system of different electron acceleration voltages have been simulated with finite element method (FEM). The global thermal effect affected by the friction force between the wafer and the wafer chuck as well as different thermal conductivities of the chuck material are simulated. Furthermore, the thermal effects of different lithography systems such as EUV scanners and conventional optical scanners are compared. The thermal effects of MEBDW systems are shown to be acceptable.