Patent ID: 8644075

Claim:
A non-volatile storage system, comprising: a set of non-volatile storage elements formed in NAND strings on a substrate, including a NAND string selected for programming in a program-verify iteration and a NAND string unselected for programming in the program-verify iteration, the set of non-volatile storage elements is in communication with a plurality of word lines, including a selected word line which is selected for programming in the program-verify iteration, and unselected word lines which are unselected for programming in the program-verify iteration; and a control circuit, the control circuit, in connection with a program portion of the program-verify iteration: configures the unselected NAND string to allow boosting in the substrate below the unselected NAND string, applies an isolation voltage to one of the unselected word lines to create at least first and second channel regions in the substrate below the unselected NAND string, on either side of the one of the unselected word lines, the selected word line extending directly over the first channel region, and at a step up time which is before a program pulse time period: to boost the first channel region: steps up a voltage which is applied to one of the unselected word lines which extends directly over the first channel region, to a respective pre-program pulse voltage of the one of the unselected word lines which extends directly over the first channel region; and to boost the second channel region: steps up a voltage which is applied to one of the unselected word lines which extends directly over the second channel region, to a respective pre-program pulse voltage of the one of the unselected word lines which extends directly over the second channel region, at a faster rate than a rate at which the voltage applied to the one of the unselected word lines which extends directly over the first channel region.