Study of Hafnium(Hf) and Gadolinium (Gd) Nanocrystal Flash Memory with Rapid Thermal Annealing Treatment

• Main Authors: Jian Yi Wong, 翁健益
• Other Authors: C.S.Lai
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/69830188611430566954

碩士 === 長庚大學 === 電子工程研究所 === 95 === Poly-silicon has been used as the charge trap/storage layer in floating gate flash memory for a long time. Poly-silicon is a very reliable material and is fully compatible with the current CMOS process flow. However, poly-silicon shows some intrinsic disadvantages and thus may not be the ultimate charge trap/storage material for scaled flash memory technology. In this work, we propose metal-rich Hafnium (Hf) and Gadolinium (Gd) NC memory that are fully compatible with the current CMOS technologies. The memory window of Hf nanocrystal is larger than the one of Gd nanocrystal as both they are under 6.5 MV/cm. After RTA treatment, the window of Gd nanocrystal is almost the same when RTA temperature increases. The window of Hf nanocrystal will narrow after RTA temperature rise. It means Gd nanocrytal has highly robust thermal stability. The speed of program can be at 1 ms and erase at 5s. Gd nanocrystal can be erased faster. The retention characteristic of Gd nanocrystal is better than Hf nanocrystal. At 85oC, the charge loss rate of Hf nanocrystal is faster than Gd nanocrystal at the same electric field. Final, superior endurance characteristics can be found in both Hf and Gd nanocrystal.