Method for fabricating flash memory device and peripheral area

Abstract

Methods for fabricating a flash memory device which improves both charge retaining characteristics and characteristics of a gate insulating film are disclosed. The methods include the steps of respectively forming a tunneling oxide film and a peripheral oxide film on a cell and peripheral areas of a semiconductor substrate; forming a floating gate line on the tunneling oxide film; forming a first insulating film on a surface of the floating gate line; forming a second insulating film on an entire surface of the semiconductor substrate; forming a third insulating film on the second insulating film so that the third insulating film is thicker than the peripheral oxide film; removing the third insulating film and the second insulating film from the peripheral area by wet etching processes; removing the peripheral oxide film by a wet etching process; forming a gate insulating film on the surface of the semiconductor substrate in the peripheral area; depositing a conductive layer on the entire surface of the semiconductor substrate; selectively removing portions of the conductive layer, the third insulating film, the second insulating film, the first insulating film, and the floating gate line to form a control gate and a floating gate in the cell area, and a gate electrode of a thin film transistor in the peripheral area; and forming source/drain impurity areas within the surface of the semiconductor substrate at both sides of the control gate and floating gate and at both sides of the gate electrode.