| 摘要 |
PURPOSE: A method for forming the alignment key of a semiconductor device is provided to improve the alignment accuracy by converting the alignment key used in the forming process of a device isolation oxide film so as to be used in the forming process of a gate electrode. CONSTITUTION: A pad oxide film and a pad nitride film(32) are formed on the wafer(31) marked out cell regions by the scribing lines. A device isolation mask having an aligning mark is aligned with the wafer(31), and shallow trenches(A) are formed in the scribing lines of the wafer(31) by etching. An oxide film for isolating devices is formed to such an extent that the trenches(A) are buried, and a device isolation film is formed by chemical mechanical polishing. The device isolation film is etched at a depth by using a key open mask. A gate oxide film and a gate conductive film is deposited, and the surfaces of the cell regions and the scribing lines are patterned by a photo mask for the gate electrode.
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