Method for forming gate stack of 3D memory device

The invention discloses a method for forming the gate stack of a 3D memory device. The method comprises the following steps that: an insulating stack structure is formed on a semiconductor substrate;a step-shaped mask layer is formed on the insulating laminated structure; a step-shaped insulating laminated structure is formed; and the insulating laminated structure is replaced with a gate laminated structure, and the height of the step-shaped mask layer is set through the material and height of the insulating laminated structure. According to the method of the invention, a gray-scale photoetching method, a nanoimprint lithography method, a gray-scale mask plate photoetching method or an ion beam gas-assisted deposition method is adopted to form a step-shaped mask layer; a semiconductor structure is etched by using dry etching, so that the pattern of the mask layer is transferred into the insulating laminated structure; and therefore, process steps are reduced, and process complexity is reduced. 公开了一种3D存储器件栅叠层