Fabrication of the nanoimprint mold with deep-subwavelength structures

To overcome the disadvantages of high-cost, low-efficiency and the difficulty in the realization of the high aspect ratio structure in the fabrication of nanoimprint mold with deep-subwavelength structures by electron beam lithography (EBL), the holographic immersion lithography - ion beam etching is adopted. There are two major challenges of this method: the holographic immersion lithography and the ion beam etching. The former one is to fabricate the photoresist mask with deep-subwavelength structures; and the latter one is to transfer the photoresist mask to the fused silica. Both the two steps have been optimized to achieve the accurate control of the high aspect ratio of the profile. The experiment indicates that titled rotation of the ion beam etching combined with reactive ion beam etching can achieve the accurate control of the high aspect ratio structure. The nanoimprint mold with the period of 180nm and the groove depth of 233nm has been fabricated.