Optical Design and Engineering

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

[+] Author Affiliations
Ri Wen Ni, Jun Zhu Huang

Huazhong University of Science and Technology, School of Optical and Electronic Information, Room 118, Building of West 1, Wuhan 430074, China

Bi Jian Zeng, Teng Luo, Zhen Li, Xiang Shui Miao

Huazhong University of Science and Technology, School of Optical and Electronic Information, Room 118, Building of West 1, Wuhan 430074, China

Huazhong University of Science and Technology, Wuhan National Laboratory for Optoelectronics, Room 118, Building of West 1, Wuhan 430074, China

Opt. Eng. 54(4), 045103 (Apr 20, 2015). doi:10.1117/1.OE.54.4.045103
History: Received December 13, 2014; Accepted March 24, 2015
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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 15μm, the widths of the crystalline patterns are obtained in a broad range from 690 nm to 8.13μm 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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© 2015 Society of Photo-Optical Instrumentation Engineers

Citation

Ri Wen Ni ; Bi Jian Zeng ; Jun Zhu Huang ; Teng Luo ; Zhen Li, et al.
"Exposure strategy and crystallization of Ge-Sb-Te thin film by maskless phase-change lithography", Opt. Eng. 54(4), 045103 (Apr 20, 2015). ; http://dx.doi.org/10.1117/1.OE.54.4.045103


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