Method of manufacturing self-aligned T-shaped gate through dual damascene
 A new method is provided to manufacture a T-shaped gate. A layer of insulation is deposited over a semiconductor surface (typically the surface of a substrate), a dual damascene structure containing a via opening and a conducting line trench is created in the layer of insulation. A layer of sacrificial oxide is grown and subsequently removed (preventing initial surface defects and providing protection during subsequent steps of etching). A layer of gate oxide is selectively grown on the bottom of the dual damascene opening. A layer of poly is deposited over the layer of insulation thereby including the dual damascene opening, the poly is planarized down to essentially the top of the dual damascene structure and the insulation is removed from above the surface of the substrate in the regions surrounding the dual damascene structure leaving the dual damascene structure in place. 
Taiwan Semiconductor Manufacturing Company
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Wei-Jen Yen-Ming Kuo-Chou Shih-Chi
Liu Chen Liu Lin