Word line-dependent ramping of pass voltage and program voltage for three-dimensional memory

摘要

Techniques are provided for programming a three-dimensional memory device while minimizing over-programming and program disturb. When a selected word line is at the source-side of a set of word lines, a channel gradient is created in the channel adjacent to the selected word line when a program voltage is applied. The gradient generates hot carriers which can cause over-programming of memory cells connected to the selected word line. To reduce the amount of hot carriers, a ramp rate and/or duration of a first step up of the program voltage is reduced. When the selected word line is not at the source-side of the set of word lines, a baseline ramp rate and/or duration can be used. A ramp rate and/or duration of the voltage applied to unselected word lines can be reduced as well but by a lesser amount.

主权项

1. An apparatus, comprising:
a set of word lines; a string comprising a set of data memory cells extending from a group of one or more source-side data memory cells at a source-side of the string to a drain-side data memory cell at a drain-side of the string, wherein the string is among a plurality of strings of memory cells; and a control circuit, the control circuit, to perform a program loop for a selected data memory cell in the set of data memory cells in the string, where the selected data memory cell is connected to a selected word line in the set of word lines, is configured to provide one increase and then another increase in a voltage of the selected word line, wherein at least one of a rate or a duration of the one increase is lower when the selected data memory cell is among the group of one or more source-side data memory cells in the string than when the selected data memory cell is not among the group of one or more source-side data memory cells in the string.