Automatic programming algorithm for page mode flash memory with variable programming pulse height and pulse width

摘要

PCT No. PCT/US95/07376 Sec. 371 Date Mar. 12, 1996 Sec. 102(e) Date Jun. 7, 1995 PCT Filed Mar. 12, 1996A method for programming a flash memory array which insures fast programming to substantially all of the cells in the array, without over-programming, based on providing a pattern of program retry pulses which have respective pulse widths and pulse heights which vary according to a pattern. The pattern includes a combination of both increasing pulse widths and increasing pulse heights. The pattern includes a first phase which completes in a specified amount of time including a predetermined number of retries so that substantially all of the cells in the array are programmed within the first phase. A second phase of the patter involves a sequence of higher energy pulses addressed to programming the slowest cells in the array. When used in a page program array, in which individual cells which are programmed fast do not receive subsequent retry pulses, a very fast and reliable programming scheme is achieved.