| 摘要 |
<p>A method for fabricating a flash memory device is provided to prevent a tunnel oxide layer at the lower corner of a first polysilicon layer from being thickened or sharpening of the corner of the first polysilicon layer by forming the first polysilicon layer having a small grain size. An isolation layer(110) is formed in a semiconductor substrate(100) to define an active region and a field region. After a tunnel oxide layer(112) is formed on the active region, a first polysilicon layer(114) having a small grain size is formed on the resultant structure. A second polysilicon layer(116) having a greater grain size than that of the first polysilicon layer is formed on the resultant structure. After the first and second polysilicon layer are polished until the upper part of the isolation layer is exposed, the upper part of the isolation layer is partially etched. A dielectric layer(118) and a conductive layer(120) for a control gate are formed on the resultant structure. The first polysilicon layer can be made of an undoped polysilicon layer in a chamber by an LPCVD method.</p> |
