| 摘要 |
A method of forming a metal plug 18 in a contact hole (19) formed in a insulating layer 13 on a silicon substrate 11, comprises depositing a metallic barrier layer 14, e.g. of Ti and TiN, over the whole structure, depositing first and second metal layers 15,(16) on the barrier layer, e.g. by CVD or PVD, etching away most of the second metal layer to leave only a portion 16a on the side walls of the contact hole, forming a third metal layer 17 over the first and remaining portion of the second layer such that the third layer fills the hole, and then etching the first and third metal layers to leave a metal plug 18 in the hole. The first and third metal layers are preferably of the same material selected from the group Al, Cu and W. The second metal layer may be TiN, Ru, RuO 2 or WN 2 . The side wall portions 16a of the second metal layer induce growth of the metal of the third layer in the hole in a single direction, thereby preventing overetching in the final etching step.
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