Method for improving in-plane uniformity of word line polycrystalline silicon process surface of flash memory device

• Main Authors: LI YONG, LI XIANHONG, SUN JIAN, RUIHUAN WANG, WANG DAXIAN, YU PENG
• Format: Patent
• Language: Chinese; English
• Published: 03.05.2024
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

The invention discloses a method for improving in-plane uniformity of a word line polycrystalline silicon process of a flash memory device, which comprises the following steps of: providing a flash memory device, forming a plurality of split gate structures arranged at intervals in the flash memory device, forming side wall isolation on two sides of each split gate structure, and forming a hard mask layer at the top of each split gate structure, word line polycrystalline silicon is deposited above the hard mask layer and between the split gate structures; removing the word line polycrystalline silicon higher than the hard mask layer by adopting a chemical mechanical polishing process; etching the word line polycrystalline silicon between the split gate structures by adopting a first etching process until the target etching depth is reached; and etching the top of the hard mask layer, the top of the side wall isolation and the residual word line polycrystalline silicon at different selection ratios by adopting