METHOD FOR MANUFACTURING FLASH MEMORY DEVICE

摘要

PURPOSE: A method for manufacturing a flash memory device is provided to prevent a characteristic of a gate insulator from decreasing by preventing a damage of a semiconductor substrate by deleting an upper oxide layer and a nitride layer in a peripheral area by wet etching. CONSTITUTION: A method for manufacturing a flash memory device includes a first through eleventh steps. The first step is to form a tunneling oxide layer(33) and a peripheral portion oxide layer(34) on a semiconductor substrate(31) defining a cell area and a peripheral area. The second step is to form a floating gate line(35) on the tunneling oxide layer. The third step is to form a first insulating layer(36) on the surface of the floating gate line. The fourth step is to form a second oxide film(37) on the overall semiconductor substrate. The fifth step is to form a third oxide layer(38) thicker than the peripheral portion oxide layer on the second oxide layer. The sixth step is to delete the second oxide layer and the third oxide layer of peripheral area by wet etching. The seventh step is to delete the peripheral portion oxide layer by performing a wet etching process on the semiconductor substrate. The eighth step is to form a gate insulating layer(40) on the surface of the semiconductor substrate of the peripheral area. The ninth step is to deposit a conductive layer on the overall semiconductor substrate. The tenth step is to form a control gate and a gate electrode of the floating gate and a thin film transistor by selectively deleting the conductive layer, the third insulating layer, the second insulating layer, the first insulating layer and the floating gate line. The eleventh step is to form a source/drain impurity area(43) within the surface of the semiconductor substrate of the control gate and both the floating gate and the gate electrode.