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Optical Engineering

Exposure strategy and crystallization of Ge-Sb-Te thin film by maskless phase-change lithography
Author(s): Ri Wen Ni; Bi Jian Zeng; Jun Zhu Huang; Teng Luo; Zhen Li; Xiangshui Miao
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Paper Abstract

Maskless phase-change lithographic technology is developed as a photoresist of phase-change materials. The controllable growth behavior of the crystallization region on an amorphous thin film of Ge2Sb2Te5 (GST) irradiated by a laser beam is investigated; the GST thin film is deposited on a silicon substrate by the sputtering method. The results of a series of the experiments and the simulations all show that the width of a crystalline pattern is not only closely related to laser power and pulse duration, but also is apparently affected by the interactive area between the focused laser spot and thin film. The width maintains a nonlinear growth with the enhancement of the laser power until the thin film approaches melting, whereas it gradually reaches a constant value due to the local thermal equilibrium. This equilibrium makes the width irrelevant to the moving velocity with certain constraints when the laser works in continuous-wave mode. Within a defocus range of 15  μm, the widths of the crystalline patterns are obtained in a broad range from 690 nm to 8.13  μm under a 0.4-NA objective lens. By adjusting the defocus amount, some crystalline square patterns with expected widths in a wide range are fabricated, and the mean percentage error between the expected and fabricated widths is only 1.495%.

Paper Details

Date Published: 20 April 2015
PDF: 7 pages
Opt. Eng. 54(4) 045103 doi: 10.1117/1.OE.54.4.045103
Published in: Optical Engineering Volume 54, Issue 4
Show Author Affiliations
Ri Wen Ni, Huazhong Univ. of Science and Technology (China)
Bi Jian Zeng, Huazhong Univ. of Science and Technology (China)
Jun Zhu Huang, Huazhong Univ. of Science and Technology (China)
Teng Luo, Huazhong Univ. of Science and Technology (China)
Zhen Li, Huazhong Univ. of Science and Technology (China)
Xiangshui Miao, Huazhong Univ. of Science and Technology (China)

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