Patents by Inventor Sam S. D. Chu

Sam S. D. Chu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5400286
    Abstract: Word line stress is used to narrow the distribution of threshold voltages after an erase of an array of memory cells. One embodiment of the invention provides a method for erasing an array including a standard erase technique followed by extra erase pulses to create a margin between threshold voltages of the cells and the erase verify level, then applying word line stress to narrow the distribution of threshold voltages. Another embodiment in addition includes verifying that all of the memory cells are still erased after applying word line stress and if any of the memory cells were over-stressed and are not erased, repeating the method but using less word line stress. The erase methods according to embodiments of the present invention can be implemented by an external CPU which executes an erase program or by circuitry embedded in an EEPROM.
    Type: Grant
    Filed: August 17, 1993
    Date of Patent: March 21, 1995
    Assignee: Catalyst Semiconductor Corp.
    Inventors: Sam S. D. Chu, Calvin V. Ho