INTEGRATION OF SINGLE-LEVEL AND MULTI-LEVEL FLASH CELLS HAVING DIFFERENT TUNNEL OXIDE THICKNESSES

摘要

Techniques are disclosed for SLC blocks having different characteristics than MLC blocks such that SLC blocks will have high endurance and MLC blocks will have high reliability. A thinner tunnel oxide (712b) may be used for memory cells in SLC blocks (202b) than for memory cells in MLC blocks (202a). A thinner tunnel oxide in SLC blocks may allow a lower program voltage to be used, which may improve endurance. A thicker tunnel oxide (712a) in MLC blocks may improve data retention. A thinner IPD (708b) may be used for memory cells in SLC blocks than for memory cells in MLC blocks. A thinner IPD may provide a higher coupling ratio, which may allow a lower program voltage. A lower program voltage in SLC blocks can improve endurance. A thicker IPD (708a) in MLC blocks can prevent or reduce read disturb. SLC blocks may have a different number of data word lines than MLC blocks.