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对低能电子在光刻胶和衬底中的复杂散射过程进行分析和物理建模,采用Monte Carlo方法进行模拟研究。利用Browning拟合公式来解决Mott弹性散射截面计算速度慢的问题,采用D.C.Joy和S.Luo修正的Bethe能量损耗公式计算低能电子在固体中的能量损耗。通过跟踪电子的散射轨迹、计算电子的能量沉积密度、结合显影阈值模型,模拟出了电子束光刻的三维显影轮廓图。据此研究了入射电子束能量、剂量、光刻胶厚度、衬底材料、衬底和光刻胶形貌等不同条件下电子束曝光邻近效应的影响。此外,还将具有高斯分布特征的低能电子束入射产生的沉积能量密度进行移动处理,模拟一个以“T”字型为代表的较为复杂图形的电子束曝光过程,通过三维显影轮廓模拟图比较直观地显示了邻近效应的影响,并演示了采用电子束曝光剂量补偿的方法实现邻近效应校正的效果。
The complex scattering process of low energy electrons in photoresist and substrate is analyzed and physically modeled. The Monte Carlo method is used to simulate. The Browning fitting formula is used to solve the problem of slow calculation of the elastic scattering cross section of Mott. The energy loss of low energy electrons in solid is calculated by Bethe energy loss formula modified by D.C.Joy and S.Luo. By tracking the trajectories of electrons and calculating the energy deposition density of the electrons, the 3D imaging profile of electron beam lithography was simulated with the development threshold model. Based on this, the effects of electron beam energy, dose, photoresist thickness, substrate material, substrate and photoresist morphology on the proximity effects of electron beam exposure were studied. In addition, the deposition energy density generated by low-energy electron beam incident with Gaussian distribution is also shifted to simulate a relatively complex pattern of electron beam exposure represented by the “T” shape. The three-dimensional development contour simulation The effect of the proximity effect is more intuitively demonstrated, and the effect of correcting the proximity effect with the method of electron beam exposure dose compensation is demonstrated.