System to reduce stress on word line select transistor during erase operation

摘要

A system for erasing a non-volatile storage system that reduces the voltage across the word line select transistors which interface between the word lines and global control lines. The use of the lower voltage across the word line select transistors allows for the word line select transistors to be made smaller. The use of smaller components allows the non-volatile storage system to include more memory cells, thereby providing the ability to store more data.

主权项

1. A method for operating non-volatile storage, comprising:
prior to erasure, maintaining voltages of word lines and a well voltage of a well on which non-volatile storage elements are formed and connected to the word lines, at a same starting voltage; at the start of erasure, temporarily turning on a first word line switch that connects an unselected one of the word lines to a global control line, where the unselected word line is connected to a first set of the non-volatile storage elements that are not to be erased during a current erase operation, where the global control line is also connected to a selected one of the word lines via a turned-on second word line switch, where the selected word line is connected to a second set of the non-volatile storage elements that are to be erased during the current erase operation; applying an above ground first voltage on the global control line at least after the first word line switch is temporarily turned on; raising the well voltage for the first set of non-volatile storage elements and the second set of non-volatile storage elements from the starting voltage to the first voltage and then to an intermediate voltage level that is less than an erasure suitable voltage while the first word line switch is still temporarily turned on; and turning off the first word line switch and raising the well voltage above the intermediate voltage level and to a particular voltage that is suitable for erasing the second set of non-volatile storage elements while the first word line switch is turned off and its unselected word line therefore floats, wherein due to the floating of the unselected word line the first set of non-volatile storage elements do not erase in response to the well voltage being at the particular voltage.