Structures and methods for fabricating staircase regions of a three-dimensional nand memory device

Abstract

In a method for fabricating a semiconductor device, a stack of alternating insulating layers and sacrificial layers are formed over a substrate. A staircase having a plurality of steps are formed in the stack. Each of the steps has a tread and a riser and further includes a respective pair of the insulating layer and the sacrificial layer over the insulating layer of the respective step. A dielectric layer is formed along the treads and risers of the steps and is doped with one or a combination of carbon, phosphorous, boron, arsenic, and oxygen. The sacrificial layers are further replaced with a conductive material to form word line layers that are arranged between the insulating layers. A plurality of word line contacts are formed to extend from the word line layers of the plurality of steps, and further extend through the dielectric layer.