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

Abstract

Thin film Al 2 O 3 /Al-rich Al 2 O 3 /SiO 2 structures were fabricated on p-Si substrates.Radio-frequency magnetron co-sputtering was used to form Al-rich Al 2 O 3 thin film as the charge-trapping layer of nonvolatile Al 2 O 3 memory. Capacitance-voltage measurements showed a large hysteresis due to charge trapping in the Al-rich Al 2 O 3 layer. The charge trap density was estimated to be 42.7 × 10 18 cm -3 , which is the largest value ever reported for an Al-rich Al 2 O 3 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 Al 2 O 3 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.

Preparation of Remote Plasma Atomic Layer-Deposited HfO2 Thin Films with High Charge Trapping Densities and Their Application in Nonvolatile Memory Devices

“…Additionally, the increase in leakage current owing to the decrease in film thickness degrades the memory retention characteristics, thereby leading to problems in terms of device reliability. To address these issues, researchers have been actively applying high-k materials, such as HfO 2 , Al 2 O 3 , TiO x , ZnO, and ZrO 2 , to CTLs [5][6][7][8][9][10]. High-k-based oxides exhibit advantages, including small equivalent oxide thicknesses (EOTs), large band offsets to Si, and high N t values, over conventional silicon nitride.…”

Influences of low-temperature postdeposition annealing on memory properties of Al/Al2O3/Al-rich Al-O/SiO2/p-Si charge trapping flash memory structures

“…23 For improving electrical properties, postdeposition annealing (PDA) is one of the key solutions, as the structural defects in the high-k films, such as oxygen vacancies and interstitial ions, can be removed by PDA treatment. 23 For improving electrical properties, postdeposition annealing (PDA) is one of the key solutions, as the structural defects in the high-k films, such as oxygen vacancies and interstitial ions, can be removed by PDA treatment.…”