Spansion LLC.

Wing Leung

Sheung-Hee Park

Yi He

Xuguang Alan Wang

Edward Franklin Runnion

Ming-Sang Kwan

Zhigang Wang

Richard M Fastow

Takao Akaogi

Yue-Song He

Ming Sang Kwan

Gwyn Robert Jones

Methods of erasing flash memory cells are provided that improve erase cycling speed and reliability. One embodiment comprises interactively applying a stepped or ramped drain voltage pattern to a drain of the memory cells and a pulsed gate voltage pattern to a gate of the memory cells for a predetermined number of gate pulses or until all the memory cells are erased. In another embodiment, an erase bias circuit is provided for erasing a sector of flash memory cells, the circuit comprising row and column decoders that selects wordline rows and columns of cells, respectively, a supply bias arrangement that provides source and drain supply voltages for the sector, and a patterned pulse bias arrangement configured to provide a pulsed gate voltage pattern to gates of the cells selected by the row decoder and a drain voltage pattern to the drains of the cells selected by the column decoder.

Cycling improvement using higher erase bias

Erase verify operations as described herein can be utilized for a flash memory device having an array of memory cells. The erase verify operations employ repetitive erase verify testing to double-check previously verified bits that might otherwise relax or settle into an under-erased state. Following an initial erase verify procedure, an erase verify operation may perform a secondary erase verify procedure and apply additional erase pulses to bits that have become under-erased.

Repetitive erase verify technique for flash memory devices

A method of erasing a block of flash memory cells by applying a ramped gate erase voltage to the block of memory cells. When an erase verify of the block of memory cells indicates that erasure has not been successfully completed another erase voltage with a greater absolute value than the initial erase voltage can be applied to the block of memory cells until erasure is complete.

Ramp gate erase for dual bit flash memory

The present invention provides a method for determining program and erase states in flash memory devices. Specifically, one embodiment of the present invention discloses a method for minimizing false detection of states in an array of non-volatile floating gate memory cells. A plurality of word lines are arranged in a plurality of rows. A plurality of bit lines are arranged in a plurality of columns. The method begins by determining a selected bit line that is associated with a column of memory cells. Then, the method continues by biasing a group of word lines at a negative voltage. The group of word lines are electrically coupled to the associated memory cells. The application of negative voltage to the group of word lines limits leakage current contributions from the associated memory cells in the column of memory cells when performing a verify operation.

Method for minimizing false detection of states in flash memory devices

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Palo Alto, CA, United States of America

Wing Leung