Xu Kai, Qin Jin, Wang Liang
Opt Lett. 2021 Oct 15;46(20):5185-5188. doi: 10.1364/OL.439623.
Direct laser writing (DLW) is a versatile and reliable lithography method widely used in many micro and nano fabrication areas. However, the resolution of DLW is limited by the optical diffraction limit. Many methods have been proposed to improve the lithography resolution, but with either high cost or increasing the complexity of the system. Here, we propose a high numerical aperture binary-amplitude-type zone plate lens that can achieve a sub-wavelength focal spot with a large depth of focus and long working distance. The critical dimension of such a lens is set at micrometer scale for ease of fabrication. By integrating the as-designed planar lens into a DLW system, we experimentally demonstrate less than 300 nm lithography resolution with exposure depth larger than 500 nm. Our results show the possibility of writing sub-micrometer scale structures with the integration of a planar lens into the DLW system, which enables miniaturization and compactness of lithography instruments for many applications.
直接激光写入（DLW）是一种用途广泛且可靠的光刻方法，在许多微纳制造领域都有广泛应用。然而，DLW的分辨率受光学衍射极限的限制。人们已经提出了许多方法来提高光刻分辨率，但要么成本高昂，要么会增加系统的复杂性。在此，我们提出了一种高数值孔径二元振幅型波带片透镜，它能够实现具有大焦深和长工作距离的亚波长焦点。这种透镜的关键尺寸设定在微米尺度，以便于制造。通过将设计好的平面透镜集成到DLW系统中，我们通过实验证明了光刻分辨率小于300纳米，曝光深度大于500纳米。我们的结果表明，将平面透镜集成到DLW系统中写入亚微米级结构是有可能的，这使得光刻仪器能够实现小型化和紧凑化，适用于许多应用。
