Method for forming a semiconductor structure

A method for forming a semiconductor structure, comprising:

• providing a substrate having a memory array region and a peripheral region thereon;
• forming a memory structure on the substrate within the memory array region, wherein a step height is formed between the memory array region and the peripheral region;
• blanketly depositing a dielectric layer over the memory array region and the peripheral region, wherein the dielectric layer covers the memory structure;
• performing a reverse etching process to remove a portion of the dielectric layer from the memory array region, thereby forming an upwardly protruding wall structure along a perimeter of the memory array region;
• subjecting the upwardly protruding wall structure to an etching process to form through channels in the upwardly protruding wall structure, thereby dividing the upwardly protruding wall structure into a plurality of islands disposed along the perimeter of the memory array region;
• and
• subjecting the dielectric layer to a polishing process to remove the plurality of islands.