| AVS 58th Annual International Symposium and Exhibition | |
| Nanomanufacturing Science and Technology Focus Topic | Tuesday Sessions |
| Session NM+MN+MS+TF-TuM |
| Session: | Lithography Strategies for Nanomanufacturing |
| Presenter: | Masaru Kurihara, Hitachi, Ltd., Tokyo |
| Authors: | M. Kurihara, Hitachi, Ltd., Tokyo M. Satake, Central Research Laboratory, Hitachi, Ltd., Japan Y. Tsuchiya, Central Research Laboratory, Hitachi, Ltd., Japan T. Nishida, Central Research Laboratory, Hitachi, Ltd., Japan Y. Tada, Hitachi Research Laboratory, Hitachi, Ltd., Japan H. Yoshida, Hitachi Research Laboratory, Hitachi, Ltd., Japan N. Negishi, Central Research Laboratory, Hitachi, Ltd., Japan |
| Correspondent: | Click to Email |
Bit-patterned media (BPM) is one of the promising candidates for hard disk media with areal density greater than 1.0Tb/in2. Nanoimprint lithography (NIL) for BPM has also been investigated as a patterning technique to reduce the production cost. One of the critical issues in NIL mold fabrication is the etching selectivity between silicon and the organic mask pattern due to the following two reasons. One is a significant decrease of pattern thickness to meet the photo-lithography requirements. This decrease remained when applying the self-assembly polymer process to fine patterning. The other is the micro-loading effect that causes the etching rate drop with pattern size shrinking.
In this work, we have developed a hard mask process to compensate for the low etching selectivity. First, the micro-loading effect in the HBr/Cl2/O2 gas chemistry was evaluated with a SiO2 hard mask of 20-nm thickness. This SiO2 hard mask was patterned from 30 to 50 nm by EB lithography and etched with CHF3 gas chemistry. The coefficients of micro-loading in silicon etching were evaluated based on the relationship between hole depth and etching time with a hole diameter of 30, 40, and 50 nm respectively. With increase of the sidewall taper angle, the micro-loading effect could be improved by about 60%. We also confirmed that there was a hole with a depth of 87 nm with a diameter of 30 nm. Extrapolating this micro-loading effect, it is expected that a hole with a depth greater than 80 nm with a diameter of 10 nm will be achieved. This result will satisfy the pattern aspect ratio of 2, which is required in NIL. We will also demonstrate the Si mold etching with a hard mask by applying the self-assembly polymer in which the areal density is greater than 1.0Tb/in2.