Improvement of charge trapping characteristics of Al2O3/Al-rich Al2O3/SiO2 stacked films by thermal annealing

• Published in: Thin solid films 2013-09, Vol.542, p.242-245
• Main Authors: Nakata, Shunji, Kato, Takashi, Ozaki, Shinya, Kawae, Takeshi, Morimoto, Akiharu
• Format: Article
• Language: English
• Subjects: Aluminum; Aluminum oxide; Annealing; Capacitance–voltage measurements; Charge; Charge trapping; Cross-disciplinary physics: materials science; rheology; Density; Deposition by sputtering; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Oxides; Physics; Radio-frequency magnetron sputtering; Silicon dioxide; Thermal annealing; Thin films; Trapping
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2013.06.005

Thin film Al2O3/Al-rich Al2O3/SiO2 structures were fabricated on p-Si substrates. Radio-frequency magnetron co-sputtering was used to form Al-rich Al2O3 thin film as the charge-trapping layer of nonvolatile Al2O3 memory. Capacitance–voltage measurements showed a large hysteresis due to charge trapping in the Al-rich Al2O3 layer. The charge trap density was estimated to be 42.7×1018cm−3, which is the largest value ever reported for an Al-rich Al2O3 layer; it is six times larger than that of a conventional metal–nitride–oxide–silicon memory. Thermal annealing was found to reduce the leakage current of the Al2O3 blocking layer, thereby providing this structure with better data retention at room temperature than an as-deposited one. In addition, the annealed structure was found to exhibit good data retention even at 100°C. •Thin film structures Al2O3/Al-rich Al2O3/SiO2 were fabricated on p-Si substrates.•Charge trap density is estimated to be 42.7×1018cm−3.•This is six times larger than that of conventional metal–nitride–oxide–silicon memory.•The annealed structure shows good data retention even at 100°C.