| 摘要 |
<p>A method for fabricating a flash memory device is provided to form an interlayer dielectric with a uniform thickness and improve anti-oxidation of the interlayer dielectric by forming a floating gate without a void or a seam. A pad oxide layer and a pad nitride layer are formed on a semiconductor substrate(10) having an active region and a field region. The pad nitride layer, the pad oxide layer and the semiconductor substrate in the field region are etched to form a trench. An isolation layer is formed in the trench. The pad nitride layer and the pad oxide layer are removed to expose the semiconductor substrate in the active region and the upper part of the isolation layer. A first polysilicon layer(17) is formed on the resultant structure. The first polysilicon layer is planarized and removed to expose the isolation layer. An etch-back process is performed by using fluorine-based gas like SF6 or CF4 to remove the void and the seam naturally generated in the first polysilicon layer. A second polysilicon layer is formed on the resultant structure. The second polysilicon layer is planarized and removed to expose the isolation layer to form a floating gate composed of the first and second polysilicon layers.</p> |
