US Patent 10998329 Methods and apparatus for three dimensional NAND structure fabrication

Methods and apparatus for forming a plurality of nonvolatile memory cells are provided herein. In some embodiments, the method, for example, includes forming a plurality of nonvolatile memory cells, comprising forming, on a substrate, a stack of alternating layers of metal including a first layer of metal and a second layer of metal different from the first layer of metal; removing the first layer of metal to form spaces between the alternating layers of the second layer of metal; and one of depositing a first layer of material to partially fill the spaces to leave air gaps therein or depositing a second layer of material to fill the spaces.