METHOD OF MANUFACTURING FLASH MEMORY DEVICE FOR KEEPING DISTRIBUTION OF THRESHOLD VOLTAGE CONTROLLING IONS CONSTANT WITHIN ACTIVE REGION

摘要

PURPOSE: A method of manufacturing a flash memory device is provided to keep the distribution of threshold voltage controlling ions constant within an active region by lowering the temperature of an oxidation for forming a sidewall oxide layer in a trench and performing an ion-implantation for compensating the active region for diffused ions. CONSTITUTION: A first ion-implantation for controlling a threshold voltage is performed on a semiconductor substrate(100). A tunnel oxide layer(102), a first polysilicon layer(104) and a pad nitride layer(106) are sequentially formed thereon and a trench is formed in the substrate by performing etching on the resultant structure. A sidewall oxide layer(112) is formed along the entire surface of the trench by using a dry-oxidation at a temperature range of 800 to 950. A second ion-implantation for compensating the threshold voltage controlling ions diffused into the sidewall oxide layer is performed thereon. An oxide layer is filled in the trench.