Blaikie R J, McNab S J
Appl Opt. 2001 Apr 1;40(10):1692-8. doi: 10.1364/ao.40.001692.
Simulation results are presented to illustrate the main features of what we believe is a new photolithographic technique, evanescent interferometric lithography (EIL). The technique exploits interference between resonantly enhanced, evanescently decaying diffracted orders to create a frequency-doubled intensity pattern in the near field of a metallic diffraction grating. It is shown that the intensity in a grating's near field can be enhanced significantly compared with conventional interferometric lithography. Contrast in the interference pattern is also increased, owing to a reduction in the zeroth-order transmission near resonance. The pattern's depth of field reduces as the wavelength is increased beyond cutoff of the first-order diffracted components, and results are presented showing the trade-offs that can be made between depth of field and intensity enhancement. Examples are given for a 270-nm-period grating embedded in material with refractive index n = 1.6 and illuminated with wavelengths near 450 nm. Under these conditions it is predicted that high-intensity, high-contrast patterns with 135-nm period can be formed in photoresists more than 50 nm thick.
给出了模拟结果，以说明我们认为是一种新型光刻技术——倏逝干涉光刻（EIL）的主要特征。该技术利用共振增强、倏逝衰减的衍射级次之间的干涉，在金属衍射光栅的近场中产生倍频强度图案。结果表明，与传统干涉光刻相比，光栅近场中的强度可显著增强。由于共振附近零级透射率降低，干涉图案的对比度也有所提高。当波长增加到超过一阶衍射分量的截止波长时，图案的景深减小，并给出了显示景深与强度增强之间权衡关系的结果。给出了一个周期为270 nm、嵌入折射率n = 1.6的材料中、用450 nm附近波长照射的光栅示例。在这些条件下，预计可在厚度超过50 nm的光刻胶中形成周期为135 nm的高强度、高对比度图案。
