Andrew Trisha L, Tsai Hsin-Yu, Menon Rajesh
Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.
Science. 2009 May 15;324(5929):917-21. doi: 10.1126/science.1167704. Epub 2009 Apr 9.
In the past, the formation of microscale patterns in the far field by light has been diffractively limited in resolution to roughly half the wavelength of the radiation used. Here, we demonstrate lines with an average width of 36 nanometers (nm), about one-tenth the illuminating wavelength lambda1 = 325 nm, made by applying a film of thermally stable photochromic molecules above the photoresist. Simultaneous irradiation of a second wavelength, lambda2 = 633 nm, renders the film opaque to the writing beam except at nodal sites, which let through a spatially constrained segment of incident lambda1 light, allowing subdiffractional patterning. The same experiment also demonstrates a patterning of periodic lines whose widths are about one-tenth their period, which is far smaller than what has been thought to be lithographically possible.
过去，利用光在远场中形成微观图案时，其分辨率受到衍射限制，大致为所用辐射波长的一半左右。在此，我们展示了通过在光刻胶上方施加一层热稳定的光致变色分子薄膜，制作出平均宽度为36纳米（nm）的线条，约为照明波长λ1 = 325 nm的十分之一。同时照射第二个波长λ2 = 633 nm，使该薄膜对写入光束不透明，除了在节点位置，这些节点会让入射的λ1光的空间受限部分通过，从而实现亚衍射图案化。相同的实验还展示了周期性线条的图案化，其宽度约为周期的十分之一，这远比人们认为光刻所能达到的尺寸要小得多。
