| 摘要 |
PURPOSE: A method for manufacturing a flash EEPROM cell is provided to prevent a problem that a chip size is increased due to a field oxide film widely formed. CONSTITUTION: A method for manufacturing a flash EEPROM cell sequentially forms a tunnel oxide film(202), an undoped polysilicon layer, the first oxide film and a nitride film on a semiconductor substrate(201). A photoresist film pattern in which a field region is open is formed on the nitride film by means of lithography process using a mask for a floating gate. The exposed portions of the nitride film and the first oxide film are sequentially removed by means of etching process using the photoresist film pattern as an etch mask and the photoresist film pattern are then removed. A channel stop region(208) is formed in the semiconductor substrate(201) at a portion where a field oxide film will ne formed by impurity ion implantation process. A field oxide film(207) is grown by means of oxidization process using the nitride film as an oxidization prevention film. The nitride film is removed by means of wet etching process. Impurities are doped into the undoped polysilicon layer so that it becomes the first doped polysilicon layer(203A). A nitride film and an oxide film are sequentially formed on the first oxide film to form an ONO dielectric film(209). The second doped polysilicon layer(210) and the second oxide film(211) are sequentially formed on the ONO dielectric film(209). The second oxide film(211), the second doped polysilicon layer(210), the ONO dielectric film(209) and the first doped polysilicon layer(203A) are etched by self-alignment etching method to form a floating gate and a control gate.
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