Patent Number: 6,166,956

Title: Fast flash EPROM programming and pre-programming circuit design

Abstract: A circuit for speeding up the pre-programming of floating gate storage transistors such as FLASH EPROMS, and particularly speeding up the pre-programming of a block or array of floating gate storage transistors includes a controllable voltage source that supplies gate programming potential across the control gate and source of the FLASH EPROM transistor cells to be programmed. A control circuit is provided that controls the voltage source to vary the gate programming potential during a programming interval as a function of time in order to decrease the time required for a given amount of charge movement to program the selected floating gate transistors. The wordline voltages are varied, while the source voltage is held constant. By starting at a lower wordline voltage, and increasing during the programming interval to a high wordline voltage, the programming speed is increased, and the high final turn-on threshold voltage for the programmed floating gate storage transistors is achieved. In addition, in order to speed up pre-programming, a programming potential is applied to four wordlines in parallel during a single programming interval. Further, the load on cells being programmed is adjusted to improve programming speed.

Inventors: Yiu; Tom Dang-Hsing (Milpitas, CA), Wan; Ray L. (Milpitas, CA), Hsiao; Ling-Wen (Taipei, CN), Lin; Tien-Ler (Cupertino, CA), Shone; Fuchia (Hsinchu, CN)

Assignee: Macronix International Co., Ltd.

International Classification: G11C 16/10 (20060101); G11C 16/16 (20060101); G11C 16/24 (20060101); G11C 16/12 (20060101); G11C 16/06 (20060101); G11C 007/00 ()

Expiration Date: 12/26/2017