Preparation method of flash memory device

• Main Authors: JIANG YANGFAN, FENG DAGUI, LI XIANHONG, WU CHANGMING, SUN JIAN, WANG DAXIAN, YU PENG
• Format: Patent
• Language: Chinese; English
• Published: 15.03.2024
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

The invention provides a preparation method of a flash memory device, which comprises the following steps: providing a substrate, forming a flash memory structure on the substrate in a storage area, forming a gate dielectric layer on the substrate in a peripheral logic area, and forming a step at the junction of the storage area and the peripheral logic area; forming a polycrystalline silicon layer; photoetching reworking is carried out; ashing to remove the photoresist layer at the storage area and the step position, and forming an oxide layer on the storage area and the step in the ashing process; etching the oxide layer for the first time; etching the oxide layer for the second time; performing main etching on the polycrystalline silicon layer; and carrying out over-etching on the residual polycrystalline silicon layer. According to the invention, the oxide layers on the storage region and the step are etched for the first time, and the remaining oxide layer on the step is etched for the second time, so th