The Preparation And Study Of Silicon Quantum Dots Double Barrier Memory And Study Of Its QDs Wrapping Layer

With the development of integrated circuit, the characteristic size of semiconductor memory are constantly shrinking. Quantum effect will become a disaster to the performance of the memory when it get into nanometer level. The situation requires us to design a kind of new memory with new structure. Quantum dots(QDs) with coulomb block effect and quantum confined effect can replace floating gate in traditional FLASH and EEPROM memory to storage electronics. Its quantum effect can help memory realize separation of electronics storage, which is benefit to reduce the leakage current. Based on the traditional single silicon quantum dots memory, we put forward silicon quantum dots memory with double barrier, which is potential to improve the performance of device.SiCx thin films containing silicon quantum dots were prepared by PECVD and thermal annealing. Transmission electron microscopy(TEM) observation shows that a large of QDs grew in it, the diameter of silicon quantum dots is about 3 to 10 nm. Memory structure with double barrier which consist of SiCx thin films containing silicon quantum dots were prepared. TEM observations shows that the above process successfully prepared Si3N4/SiCx/Si-QDs/SiCx/SiO2 double-barrier memory structure.Based on the programming mechanism of single barrier memory, programming mechanism of double barrier memory is studied. Programming progress of double barrier and single memory are simulated, the threshold voltage shift of two kinds of devices were calculated too. The double barrier memory has a threshold voltage of 3.6V, when the programing voltage is 6V; The single barrier memory has a smaller threshold voltage of 1.5V under the same situation. The C-V characteristic curve of double barrier memory structure prepared by experiment were measured. The results show that double barrier memory structure has a memory window of 9V with scanning voltage various form 10 V to-10 V. Both simulation and experiment results show that double barrier quantum dots memory has a greater memory window.The different performance of double barrier memory with silicon carbide or silicon nitride as the wrapping layer of silicon QDs are studied. The analysis indicates that double barrier memory with silicon carbide as the wrapping layer of silicon QDs has a bigger memory window. The programming progress of two kinds of double barrier memory were both simulated. The simulation results show that double barrier memory with silicon carbide as the wrapping layer of silicon QDs has a greater threshold voltage shift. Double barrier memory with silicon carbide or silicon nitride as the wrapping layer of silicon QDs are both prepared, and they C-V characteristic curve were tested. The results show that ouble barrier memory with silicon nitride as the wrapping layer of silicon QDs has a memory window of 2V with scanning voltage various form 10 V to-10 V. It's a smaller memory window compares to memory with silicon carbide as the wrapping layer of silicon QDs(10V). The different performance of double barrier memory with silicon carbide or silicon nitride as the wrapping layer of silicon QDs are studied. And the programing progress of double barrier memory with silicon carbide or silicon nitride as the wrapping layer of silicon QDs are simulated. The analysis indicates that double barrier memory with silicon carbide as the wrapping layer of silicon QDs has a bigger memory window. The simulation results show that double barrier memory with silicon carbide as the wrapping layer of silicon QDs has a threshold voltage shift of 3.4V which is greater than the silicon nitride one that has a a threshold voltage shift of 2.8V. Double barrier memory with silicon carbide or silicon nitride as the wrapping layer of silicon QDs are prepared, and they C-V characteristic curve were tested. The results show that Double barrier memory with silicon nitride as the wrapping layer of silicon QDs has a memory window of 2V with scanning voltage various form 10 V to-10 V. It's a smaller memory window compares to memory with silicon carbide as the wrapping layer of silicon QDs(10V).