Patent ID: 7705387

Claim:
A non-volatile storage system, comprising: a substrate having ions at a first depth but not as deep as a second depth, and ions at the second depth, the second depth is deeper than the first depth; and a NAND string formed, at least in part, over the substrate, the NAND string extends in a bit line direction and comprises a set of series-connected non-volatile storage elements, where the ions at the first depth extend along a length of the NAND string, from one end of the NAND string to another end of the NAND string, so that all of the non-volatile storage elements in the NAND string are located directly over the ions at the first depth, and the ions at the second depth extend along a first interval of the substrate along the length of the NAND string, but not along a second interval of the substrate along the length of the NAND string, the second interval is adjacent to the first interval in the bit line direction, so that a first subset of multiple non-volatile storage elements in the NAND string is located directly over the first interval and the ions at the second depth, and a second subset of multiple non-volatile storage elements in the NAND string which does not include the first subset of multiple non-volatile storage elements is located directly over the second interval but is not located directly over the ions at the second depth.