Exposure strategy and crystallization of Ge-Sb-Te thin film by maskless phase-change lithography

Ri Wen Ni; Bi Jian Zeng; Jun Zhu Huang; Teng Luo; Zhen Li; Xiangshui Miao

doi:10.1117/1.OE.54.4.045103

20 April 2015 Exposure strategy and crystallization of Ge-Sb-Te thin film by maskless phase-change lithography

Ri Wen Ni, Bi Jian Zeng, Jun Zhu Huang, Teng Luo, Zhen Li, Xiangshui Miao

Author Affiliations +

Optical Engineering, Vol. 54, Issue 4, 045103 (April 2015). https://doi.org/10.1117/1.OE.54.4.045103

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%.

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Ri Wen Ni, Bi Jian Zeng, Jun Zhu Huang, Teng Luo, Zhen Li, and Xiangshui Miao "Exposure strategy and crystallization of Ge-Sb-Te thin film by maskless phase-change lithography," Optical Engineering 54(4), 045103 (20 April 2015). https://doi.org/10.1117/1.OE.54.4.045103

Published: 20 April 2015

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