Programming scheme for non-volatile flash memory

摘要

An embodiment of the present invention involves a method of programming a memory cell. The memory cell is in a first state having a maximum initial threshold voltage. The memory cell is to be programmed to one of a plurality of states having a higher target threshold voltage relative to the maximum initial threshold voltage. There is a cue voltage between the maximum initial threshold voltage and the target threshold voltage. The memory cell has a drain region. The method includes applying a drain voltage to the cell by a programming pulse having a first width, determining whether the cell has reached the cue threshold voltage, and if the cell has reached the cue threshold voltage, changing the programming pulse width from the first pulse width to a second pulse width. The second pulse width is smaller than the first pulse width.