A 3D memory device includes a plurality of ridge-shaped stacks, in the form of multiple strips of conductive material separated by insulating material, arranged as bit lines which can be coupled through decoding circuits to sense amplifiers. Diodes are connected to the bit lines at either the string select of common source select ends of the strings. The strips of conductive material have side surfaces on the sides of the ridge-shaped stacks. A plurality of word lines, which can be coupled to row decoders, extends orthogonally over the plurality of ridge-shaped stacks. Memory elements lie in a multi-layer array of interface regions at cross-points between side surfaces of the semiconductor strips on the stacks and the word lines.