| Summary: | 碩士 === 國立中央大學 === 電機工程研究所 === 98 === In this thesis, we explored two wide bandgap insulators, silicon-dioxide and silicon nitride, as a stacked dielectric for forming a tunable tunnel barrier under electric-field modulation. The so-formed tunnel dielectric behaves like a symmetric quasi-triangle potential barrier, which is expected to enhance the read and write speeds for memory application. In addition, we also incorporate germanium quantum dots (QDs) to replace the floating poly-Si gate, so that a high speed and good charge retention Ge QDs flash memory is demonstrated.
The stacked tunnel dielectric of Si3N4/SiO2/Si3N4 is produced by thermally oxidizing amorphous Si3N4 at 1050 oC and its equivalent oxide thickness (EOT) is less than 5 nm. The so-formed stacked tunnel dielectric behaves like a quasi-triangle potential barrier under E-field manipulation. Incorporating Ge QDs with the quasi-triangle tunnel barrier into the MOSFET structure, we realized a floating-dot nonvolatile memory cell transistor with the write/read voltages of +8 V and -6 V, write/read time of 1 ms and 70 μs at a threshold voltage shift (ΔVTH = 0.6 V). This Ge QDs transistor have good charge retention of 58 % after 1E8 s and excellent endurance after more than 1E6 read/write operations.
|
|---|
