| 摘要 |
PURPOSE: A method for forming a contact hole is provided to improve the large integration and the productivity of the device by increasing a contact overlap margin by forming a contact hole smaller than an exposure process limit. CONSTITUTION: A contact hole having a nitride film(34) and the second oxide side wall(35) is located on the first oxide(32). And, a poly-silicon layer(36) is located on the first oxide including the contact hole. Also, the first oxide is formed on a semiconductor substrate(31). And, the first photo resist is coated on the first oxide. And, a selective exposure and developing is performed to remove a region on the photo resist where the contact hole is to be formed. Then, after forming the contact hole by etching the first oxide selectively using the first photo resist as a mask, the first photo resist is removed. The nitride film and the second oxide are formed on the first oxide including the semiconductor substrate revealed by the contact hole. And, the second oxide side wall is formed on a side of the nitride film by etching back the second oxide. And, the nitride film is wet-etched using the second oxide side wall as a mask and the first oxide as a stopper. And, a bottom part of the contact hole and the nitride film on the first oxide are removed by wet-etching of the nitride film. After forming a poly-Si layer and the second photo resist on the first oxide, a selective exposure and developing are performed so that a part of the oxide is remained. Then, the poly-Si layer(36) is formed in the contact hole and on the oxide by etching the poly-Si layer.
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