Memory characteristics of MOSFET with silicon nanoclusters formed using a pulse-type gas-feeding technique in the LPCVD system

The digital gas-feeding method was used in this study, with Si2H6 as the source gas, in a low-pressure chemical-vapor deposition system, to grow Si nanoclusters with high densities and uniform sizes. The densities of the Si nanoclusters rose to 7 × 1011 cm−2, and their sizes slightly changed at about 7 nm based on the frequency of gas-pulse feeding in the digital process. MOSFETs containing Si nanoclusters as a floating gate in the gate stack were fabricated, and the various nonvolatile-memory characteristics of MOSFET were investigated. The total threshold voltage shift of 3.7 V was achieved, and the program/erase times were found to be 5 μs/50 ms when the program/erase voltages were +18/−20 V, respectively. The charge-storage memory window was extrapolated over 1 year to be 1.5 V in the retention measurements of the fabricated Si nanocluster floating-gate memory device.