title: A study on the fabrication of nanostructures with high aspect ratio and large area uniformity.
abstract: Nanoimprint lithography (NIL), as a promising next generation lithography method, has the advantages of high throughput, sub-10-nm feature and low cost. However, the requirements, such as the structure with high aspect ratio, large area uniformity, and pattern transfer on nonflat surface, have barely been satisfied at the same time. In this study, the authors present a novel fabrication process by introducing a three-mask-layer (TML) Soft UV NIL technique which proves to be a simple and effective method. The initial mold with low aspect ratio can guarantee the imprint uniformity on large area under a high pressure in NIL. Meanwhile, high aspect ratio structure can be easily obtained due to a high etching selectivity of SiO2 to resist in O2 plasma dry etching. Using the proposed technique to fabricate 40 nm gratings with the aspect ratio as high as 6 is proved successful. Uniform photonic crystal (PC) structures with micrometer scale nonflat steps are obtained on large area. The photoluminescence enhancements of the PC light-emitting diode (LED) fabricated by the proposed method to the one with conventional process and un-patterned LED are 1.6 fold and 2.2 fold, respectively.
authors.affiliation: Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Tangyou
authors.initials: T
authors.lastname: Sun
authors.forename: Zhimou
authors.initials: Z
authors.lastname: Xut
authors.forename: Shuangbao
authors.initials: S
authors.lastname: Wang
authors.forename: Wenning
authors.initials: W
authors.lastname: Zhao
authors.forename: Xinghui
authors.initials: X
authors.lastname: Wu
authors.forename: Sisi
authors.initials: S
authors.lastname: Liu
authors.forename: Wen
authors.initials: W
authors.lastname: Liu
authors.forename: Jing
authors.initials: J
authors.lastname: Peng
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Wang
authors.forename: Xueming
authors.initials: X
authors.lastname: Zhang
authors.forename: Jian
authors.initials: J
authors.lastname: He