Progress of UV-NIL template making

The variation of residual layer thickness (RLT) by the difference of pattern density is a difficult problem in UV nanoimprint lithography (NIL). A capacity-equalized mold was proposed to solve the problem, and the effectiveness of the concept was validated using a mold with various pattern sizes of hundreds of micrometers. However, the effectiveness should be evaluated at nanometer scales to prove the concept. Here the first challenge has been to fabricate and evaluate a two-step-depth mold with tens of nanometer patterns for the capacity-equalized mold. A two-step-depth mold with sub-100 nm patterns was fabricated by a combination of electron beam lithography and laser beam lithography. We succeeded in fabricating a two-step-structure with a width of around 40 nm, and the widths of the deeper grooves were found to have slightly increased during the second RIE process. The differences in widths were found to vary approximately from 10 to 30 nm. UV nanoimprint was carried out using the two-step-depth mold in order to examine its depth modulation, and to judge whether it could be applied to a NIL process, including a residual-layer-removal process. Fine patterns of 40 nm width were successfully transferred onto the underlying Si wafer from two-step-height resin patterns that were fabricated by UV nanoimprint.

Section: Mold Fabricationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fabrication Processes for Capacity-Equalized Mold with Fine Patterns

Suzuki

Youn

Wang

et al. 2011

“…EBL is a well-known method for realizing a pattern with the highest resolution on a resist. [18][19][20][21] In our previous studies, the line and space (L=S) and bit pattern resolutions were enhanced by EBL using a polymer positive EB resist ZEP520A with a poor (low-solubility) solvent, such as a fluorocarbon and alcohol mixture, for resist patterning and by RIE for quartz patterning. It was shown that 12-nm-hp L=S and 22-nm-bp hole patterns were realized to have the highest resolution.…”

Section: Introductionmentioning

confidence: 99%

Nanohole and dot patterning processes on quartz substrate by R–θ electron beam lithography and nanoimprinting

Watanabe¹,

Taniguchi²,

Suzuki³

et al. 2016

Fine hole and dot patterns with bit pitches (bp’s) of less than 40 nm were fabricated in the circular band area of a quartz substrate by R–θ electron beam lithography (EBL), reactive ion etching (RIE), and nanoimprinting. These patterning processes were studied to obtain minimum pitch sizes of hole and dot patterns without pattern collapse. The patterning on the circular band was aimed to apply these patterning processes to future high-density bit-patterned media (BPM) for hard disk drive (HDD) and permanent memory for the long life archiving of digital data. In hole patterning, a minimum-22-nm-bp and 8.2-nm-diameter pattern (1.3 Tbit/in.2) was obtained on a quartz substrate by optimizing the R–θ EBL and RIE processes. Dot patterns were replicated on another quartz substrate by nanoimprinting using a hole-patterned quartz substrate as a master mold followed by RIE. In dot patterning, a minimum-30-nm-bp and 18.5-nm-diameter pattern (0.7 Tbit/in.2) was obtained by introducing new descum conditions. It was observed that the minimum bp of successful patterning increased as the fabrication process proceeded, i.e., from 20 nm bp in the first EBL process to 30 nm bp in the last quartz dot patterning process. From the measured diameters of the patterns, it was revealed that pattern collapse was apt to occur when the value of average diameter plus 3 sigma of diameter was close to the bp. It was suggested that multiple fabrication processes caused the degradation of pattern quality; therefore, hole patterning is more suitable than dot patterning for future applications owing to the lower quality degradation by its simple fabrication process.

“…[7][8][9][10][11][12][13][14] A master mold for NIL is generally made by electron beam lithography (EBL) for the ultimate pattern resolution. [15][16][17][18] A polymer positive electron beam (EB) resist ZEP520A, with a poor (low-solubility) solvent developer such as a fluorocarbon and alcohol mixture, has provided the best resolution, as far as we have studied, for the last 10 years. Its resolution limit was hp 16 nm in L/S patterns and bp 22 nm hole array for BPM in a large and practical patterning area, as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

A master-mold fabrication by electron beam lithography followed by nanoimprinting and self-aligned double patterning

Watanabe¹,

Suzuki²,

Iyama³

et al. 2014

As a new scheme of master-mold fabrication, a half pitch (hp) 12 nm line and space (L/S) pattern was fabricated from hp 24 nm L/S resist mandrels, which were prepared by electron beam (EB) writing as well as nanoimprinting, followed by the self-aligned double-patterning (SADP) technique. It was observed that the line width roughness (LWR) was reduced and improved by single and multiple nanoimprintings in the new scheme of the master-mold fabrication to make hp 24 nm resist mandrels. We have studied the phenomena and revealed that the resist pattern of nanoimprinting had sharper and smoother shoulders and bottom edges in cross section than those of the EB resist. These shoulder shapes of nanoimprinting seemed to be reflected in its LWR improvement. The new scheme has advantages of resolution enhancement and better pattern quality of LWR on a master mold for nanoimprint lithography, in comparison with conventional optical and EB lithography technologies.