| 摘要 |
PROBLEM TO BE SOLVED: To optimize the threshold voltage of a CMOS transistor using a gate insulating film made of a hafnium-based high dielectric material. SOLUTION: A gate insulating film of an nMOS transistor and a pMOS transistor contains an HfO<SB>X</SB>film and HfAlO<SB>X</SB>film formed on the HfO<SB>X</SB>film. In this case, on the interface between the HfAlO<SB>X</SB>film and a gate electrode, the bond (Hf-Si bond) between a silicon atom in an n-type polycrystalline silicon film for composing the gate electrode and an Hf atom in the HfAlO<SB>X</SB>film, and the bond (Al-O-Si bond) between the silicon atom in the n-type polycrystalline silicon film and an Al atom in the HfAlO<SB>X</SB>film, are generated. By changing the concentration of Al in the HfAlO<SB>X</SB>film, control is made so that the work function of n-type polycrystalline silicon and that of p-type one becomes symmetric while sandwiching a mid gap (the threshold voltage of a MOS transistor=0). COPYRIGHT: (C)2007,JPO&INPIT
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