METHOD FOR FABRICATING HIGH-VOLTAGE TRANSISTOR OF FLASH MEMORY DEVICE TO SATISFY ACTIVE CHARACTERISTIC AND RESTRAIN PUNCH LEAKAGE CURRENT OF ISOLATION LAYER

摘要

PURPOSE: A method for fabricating a high-voltage transistor of a flash memory device to satisfy an active characteristic and restrain a punch leakage current of an isolation layer is provided to reduce the number of fabricating processes and the number of masks by using only one mask to perform ion implantation processes. CONSTITUTION: An ion implantation process for controlling a threshold voltage of a high-voltage transistor is performed on a semiconductor substrate(100). A gate oxide layer(108) for high-voltage element is formed on the semiconductor substrate. A pad nitride layer is formed on the gate oxide layer for high-voltage element. A shallow trench is formed within the semiconductor substrate. An isolation layer(120) is formed by burying an insulating layer within the shallow trench. The pad nitride layer is removed therefrom. A polysilicon layer is formed on the semiconductor substrate. A gate electrode of the high-voltage transistor is formed by patterning the polysilicon layer. A source/drain junction of the high-voltage transistor is formed by performing an ion implantation process.