THREE-DIMENSIONAL MEMORY DEVICES INCLUDING MULTI-LAYER

The invention provides a method for forming a three-dimensional memory device. The method comprises the following steps: forming a first layer alternating stack of first insulating layers and first sacrificial material layers; forming a first layer of memory openings, a first layer of support openings and a first layer of trench grooves through the first alternating stack using the same etching step; forming a first dielectric trench structure in the first trench layer trench and a first support pillar structure in the first layer support opening during the same deposition step; forming a memory stack structure in the first layer of memory openings; forming a backside trench through the first layer alternating stack after forming the first dielectric trench structure; replacing a portion of the first sacrificial material layer with a first conductive layer through the backside trench; and forming at least one through memory hierarchical interconnection via structure through a first vertically alternating sequ