| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the need for distributing accumulated charges in a floating gate to a narrow range by providing an inserting level in a floating gate voltage Vfg even if the insensing level is provided in a drain current Ids to prevent erroneous read in a EEPROM for performing multilevel data storage based on the correspondence between the floating gate voltage Vfg and the drain current Ids. SOLUTION: A channel length is set to be not greater than the mean free pass of a conduction electron, and the conduction electron is enclosed in an inverted layer from the surface of a silicon substrate to depthΔX<SB>n</SB>whereinΔX<SB>n</SB>=n×(1/2)λ<SB>x</SB>(in this case,λ<SB>x</SB>is the de Broglie wavelength of a conduction carrier and n is a natural number.), thus producing four discrete energy levels of the conduction electron in a conduction band, and hence obtaining the characteristic curve of a step-like floating gate voltage Vfg - drain current Ids. Consequently a verify loop is simplified, and a program time is shortened. COPYRIGHT: (C)2003,JPO
|
