| Summary: | 碩士 === 國立中興大學 === 電機工程學系所 === 94 === This thesis focus on the discussions about 2nd bit effect of two bits per cell storage SONOS type flash memory. In our experimental designs, the primary topics for discussion are the channel length effect and BD (source/drain) implantation dosage effect. In this study, the two bits per cell storage SONOS cell is made of an n-channel MOSFET with an oxide-nitride-oxide gate structure. Unlike conventional SONOS cell, this cell has a relatively thicker bottom oxide to avoid charge direct tunneling and is operated with channel hot electron to program and band-to-band hot hole to erase, respectively. Thus, after the program operation, we use the charge profiling methodology to extract the electron distribution trapped in the nitride and take advantage of TCAD tools to simulate process conditions and analyze the electrical characteristics. Using these simulated results, we try to understand how the channel length and source/drain implantation dosage affect 2nd bit effect as shown in our experimental data. The degrading factors of 2nd bit effect are the short channel effect and different junction shapes inducing different potential distribution, respectively.
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