Technical Solutions to Mitigate Reliability Challenges due to Technology Scaling of Charge Storage NVM

Table 3

(a) Key advantages of nanocrystal NVM as compared to standard FG flash memory. (b) Critical challenges of nanocrystal NVM.

(a)

	Key advantages of nanocrystal NVM	References
1	Excellent inherent immunity to trap assisted tunneling of SILC through defects in tunnel oxide	[38–43]
2	Tunnel oxide thickness can be further scaled down below 8 nm (critical limitation for standard FG flash memory)	[41–53]
3	Low operating voltage, fast write and erase speed	[38, 39, 41–44]
4	Multiple bit storage	[51, 58]
5	Eliminate floating gate interference especially for ultradense NAND flash memory	[52]
6	Leverage existing Si material technology and CMOS compatible process	[41–53]
7	Simpler device structure which yielded fewer process steps that further reduce fabrication costs	[40, 52]
8	Superior tolerance to radiation effects as compared to standard FG flash memory	[55, 58]
9	Nitrided silicon nanocrystal NVM has shown larger memory window and faster program speed	[47]

(b)

	Critical challenges of nanocrystal NVM	References
1	Nanocrystals are not fabricated through lithography process; thus variability in fabrication process is critical towards memory properties of nanocrystal NVM	[40–42, 50]
2	Concern on charge leakage through surrounding oxide if thinning of surrounding oxide continues and density of nanocrystals increases	[40, 41, 50, 52–54]
3	Optimal nanocrystal memory performance requires formation of nanocrystals of optimal size and density and preserving them during subsequent processing steps	[40, 41, 43–45, 50, 52, 54]
4	Impact of charge localization of nanocrystals to operating window	[54]