Annealing Effect on the Characteristics of Co40Fe40W10B10 Thin Films on Si(100) Substrate

Wen-Jen Liu; Yung-Huang Chang; Yuan-Tsung Chen; Chun-Yu Chang; Jian-Xin Lai; Shih-Hung Lin; Te-Ho Wu; Po-Wei Chi

doi:10.3390/ma14206017

Annealing Effect on the Characteristics of Co₄₀Fe₄₀W₁₀B₁₀ Thin Films on Si(100) Substrate

Materials (Basel). 2021 Oct 13;14(20):6017. doi: 10.3390/ma14206017.

Authors

Wen-Jen Liu¹, Yung-Huang Chang², Yuan-Tsung Chen³, Chun-Yu Chang³, Jian-Xin Lai³, Shih-Hung Lin⁴, Te-Ho Wu³, Po-Wei Chi⁵

Affiliations

¹ Department of Materials Science and Engineering, I-Shou University, Kaohsiung 84001, Taiwan.
² Bachelor Program in Interdisciplinary Studies, National Yunlin University of Science and Technology, 123 University Road, Section 3, Douliou 64002, Yunlin, Taiwan.
³ Graduate School of Materials Science, National Yunlin University of Science and Technology, 123 University Road, Section 3, Douliou 64002, Yunlin, Taiwan.
⁴ Department of Electronic Engineering, National Yunlin University of Science and Technology, 123 University Road, Section 3, Douliou 64002, Yunlin, Taiwan.
⁵ Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.

Abstract

This research explores the behavior of Co₄₀Fe₄₀W₁₀B₁₀ when it is sputtered onto Si(100) substrates with a thickness (t_f) ranging from 10 nm to 100 nm, and then altered by an annealing process at temperatures of 200 °C, 250 °C, 300 °C, and 350 °C, respectively. The crystal structure and grain size of Co₄₀Fe₄₀W₁₀B₁₀ films with different thicknesses and annealing temperatures are observed and estimated by an X-ray diffractometer pattern (XRD) and full-width at half maximum (FWHM). The XRD of annealing Co₄₀Fe₄₀W₁₀B₁₀ films at 200 °C exhibited an amorphous status due to insufficient heating drive force. Moreover, the thicknesses and annealing temperatures of body-centered cubic (BCC) CoFe (110) peaks were detected when annealing at 250 °C with thicknesses ranging from 80 nm to 100 nm, annealing at 300 °C with thicknesses ranging from 50 nm to 100 nm, and annealing at 350 °C with thicknesses ranging from 10 nm to 100 nm. The FWHM of CoFe (110) decreased and the grain size increased when the thickness and annealing temperature increased. The CoFe (110) peak revealed magnetocrystalline anisotropy, which was related to strong low-frequency alternative-current magnetic susceptibility (χ_ac) and induced an increasing trend in saturation magnetization (Ms) as the thickness and annealing temperature increased. The contact angles of all Co₄₀Fe₄₀W₁₀B₁₀ films were less than 90°, indicating the hydrophilic nature of Co₄₀Fe₄₀W₁₀B₁₀ films. Furthermore, the surface energy of Co₄₀Fe₄₀W₁₀B₁₀ presented an increased trend as the thickness and annealing temperature increased. According to the results, the optimal conditions are a thickness of 100 nm and an annealing temperature of 350 °C, owing to high χ_ac, large Ms, and strong adhesion; this indicates that annealing Co₄₀Fe₄₀W₁₀B₁₀ at 350 °C and with a thickness of 100 nm exhibits good thermal stability and can become a free or pinned layer in a magnetic tunneling junction (MTJ) application.

Keywords: annealed Co40Fe40W10B10 thin films; low-frequency alternating current magnetic susceptibility (χac); magnetocrystalline anisotropy; optimal resonance frequency (fres); surface energy.

Abstract

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