US 2006/0214207 A1 · Semiconductor device and manufacturing method thereof

Abstract

Threshold voltage of a CMOS transistor which uses a gate insulator made of a hafnium-based high-k material is optimized. A gate insulator of nMOS and pMOS transistors includes a HfOx film and a HfAlOx film formed thereon. At this time, silicon atoms in a n type polycrystalline silicon film which constitutes a gate electrode and Hf atoms in the HfAlOx film are bonded (Hf—Si bonding) and silicon atoms in the n type polycrystalline silicon film and Al atoms in the HfAlOx film are bonded (Al—O—Si bonding) at the interface between the HfAlOx film and the gate electrode. Consequently, the work function of the n type polycrystalline silicon and the work function of the p type polycrystalline silicon are controlled so as to be symmetrical with respect to a midgap (threshold voltage of MOS transistor=0) by changing the Al concentration in the HfAlOx film.

Claims17

Dependent claims

A semiconductor device in which a n channel MOS transistor is formed in a first region on a main surface of a semiconductor substrate made of single crystal silicon and a p channel MOS transistor is formed in a second region on said main surface,

wherein each of said n channel MOS transistor and said p channel MOS transistor comprises:
a gate insulator including a first dielectric film which contains a first element having a level of silicon bonding on a conduction band side from an energy level located at a midpoint between a conduction band and a valence band of silicon atoms and a second element having a level of silicon bonding on a valence band side therefrom;
and a gate electrode including a conductive film which contains silicon,
said first dielectric film and said conductive film are stacked on each other, and
a ratio of said first element and said second element at an interface with said conductive film and in the vicinity thereof in said first dielectric film is controlled so that a threshold voltage of said n channel MOS transistor and a threshold voltage of said p channel MOS transistor become almost symmetrical with respect to said energy level located at the midpoint.

2 more elements

Dependencies are inferred from the claim text.

Semiconductor device and manufacturing method thereof

Life of this patent

Semiconductor device and manufacturing method thereof

Life of this patent

Abstract

Claims17