Title :
High reliability electron-ejection method for high density flash memories
Author :
Kawahara, Takayuki ; Miyamoto, Naoki ; Saeki, Syun-ichi ; Jyouno, Yusuke ; Kato, Masataka ; Kimura, Katsutaka
Author_Institution :
Central Res. Lab., Hitachi Ltd., Kokubunji, Japan
fDate :
12/1/1995 12:00:00 AM
Abstract :
To minimize the electrical stress for electron-ejection of each flash memory cell, the variable word-line voltage (VVP) method and the variable pulse width (VVWP) method are proposed. Both methods make it possible to achieve high reliability while maintaining the total operating time of the conventional method, and both provide a sufficient disturb margin. Simulation results show that both methods reduce the maximum Fowler-Nordheim tunnel current density by 1.4 orders of magnitude compared to that of the conventional method, and the VVWP method increases the number of verifications by much less than the VVP method. This is expected to triple the charge-to-breakdown (Qbd ) by decreasing the trap generation. A Qbd higher than the injection charge as obtained, as needed for high density flash memories
Keywords :
EPROM; current density; integrated circuit reliability; integrated memory circuits; tunnelling; Fowler-Nordheim tunnel current density; charge-to-breakdown; disturb margin; electrical stress minimisation; electron-ejection method; high density flash memories; high reliability; trap generation reduction; variable pulse width; variable word-line voltage method; Current density; Design for quality; Dielectric films; Flash memory; Flash memory cells; Maintenance; Solid state circuits; Space vector pulse width modulation; Stress; Voltage;
Journal_Title :
Solid-State Circuits, IEEE Journal of
