A semiconductor structure includes a substrate, a first dielectric layer on the substrate, a plurality of memory stack structures on the first dielectric layer, an insulating layer conformally covering the memory stack structures and the first dielectric layer, a second dielectric layer on the insulating layer and filling the spaces between the memory stack structures, a first interconnecting structure through the second dielectric layer, wherein a top surface of the first interconnecting structure is flush with a top surface of the second dielectric layer and higher than top surfaces of the memory stack structures, a third dielectric layer on the second dielectric layer, and a plurality of second interconnecting structures through the third dielectric layer, the second dielectric layer and the insulating layer on the top surfaces of the memory stack structures to contact the top surfaces of the memory stack structures.