Memory array including memory cell strings and method for forming memory array including memory cell strings

The invention relates to a memory array including strings of memory cells and a method for forming a memory array including strings of memory cells. A method for forming a memory array including strings of memory cells includes forming a lower portion of a stack to include vertically alternating first and second layers. The stack includes regions of memory blocks that are laterally spaced apart. The material of the first layer has a different composition than the material of the second layer. The lower portion includes an upper second layer including an insulating material. The vertically alternating first and second layers of an upper portion of the stack are formed over the lower portion. A string of channel material is formed that extends through the upper portion to the lower portion. Horizontal elongated lines are formed in the upper second layer longitudinally along opposite lateral edges of the memory block region. The material of the wires has a different composition than the composition of the insula