对光刻胶内光强分布进行了计算与模拟,结果表明,来自基底的反射光与入射光干涉,光强在垂直基底的方向上呈现强弱周期性变化,即驻波效应.进一步的分析与实验结果表明,随着基底反射率的增加,驻波效应变得严重,进而影响光栅掩模的槽形、占宽比并限制线条高度.为减弱驻波效应的影响,尝试了使用减反射膜降低基底反射光强度,实验结果表明,在基底与光刻胶之间增加一层减反射膜吸收来自基底的反射光强度,减弱驻波效应的效果显著.
The distribution of intensity of incident irradiation in photo-resist during exposure is figured out,and it is shown that the pattern in photo-resist on surface with high reflectivity will suffer standing wave due to the fact that the incidence irradiation interferences with the reflective beam from the photo-resist-substrate interface.The higher the reflectivity,the worse the effect of standing wave is,and it is shown that the standing wave will have adverse effects on the profile and the duty cycle of photo-resist grating and restricts the most groove depth.Inserting a layer of anti-reflection coating(ARC) can minimize the effect of standing wave.Experimental results show that it is a good way to use ARC between photo-resist and substrate to attenuate standing wave.