Crystallization kinetics of Ga–Sb–Te films for phase change memory

• Published in: Thin solid films 2008-06, Vol.516 (16), p.5513-5517
• Main Authors: Cheng, Huai-Yu, Kao, Kin-Fu, Lee, Chain-Ming, Chin, Tsung-Shune
• Format: Article
• Language: English
• Subjects: Composition and phase identification; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystallization kinetics; Deposition by sputtering; Electrical resistance; Exact sciences and technology; Ga–Sb–Te; Ga–Sb–Te films; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; PCRAM; Phase change memory; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phase diagrams of other materials; Physics; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Theory and models of film growth; Thin film structure and morphology
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2007.07.100

Ga–Sb–Te ternary thin films were prepared by co-sputtering using targets GaSb and Sb 8Te 2. Crystallization processes of these films were studied by measuring the temperature-dependent electrical resistance during non-isothermal heating. The activation energy ( E a), rate factor ( K o), and kinetics exponent ( n) were deduced from Kissinger and Ozawa's plots, respectively. The crystallization temperatures ( T x = 108∼319°C) increase with increasing GaSb contents. The activation energy (1.82∼7.52 eV) increases with increasing Ga content until 31.6 at.% then it decreases. The crystallization mechanisms of compositions A∼D (Ga 17∼32Sb 71∼62Te 12∼6), as evidenced from n values, are nuclei formation and subsequent crystal growth; the nucleation rate decreases with grain growth. While composition E (Ga 38.2Sb 57.7Te 4.1) reveals an n value lower than 1.5, it implies the one-dimensional crystal growth from the nuclei. The crystallization time of each composition was evaluated using JMA equation using all derived kinetics parameters. Composition C (Ga 26.4Sb 65.2Te 8.4), showing the shortest crystallization time, is suggested for phase change RAM applications.