Metal gate MOS transistors and methods for making the same
First Claim
1. A method of fabricating PMOS and NMOS metal gate structures in a semiconductor device, the method comprising:
- forming a gate dielectric in PMOS and NMOS regions above a semiconductor body;
forming a metal nitride above the gate dielectric in the NMOS region;
forming a metal boride above the gate dielectric in the PMOS region;
patterning the metal nitride to form an NMOS gate structure in the NMOS region; and
patterning the metal boride to form a PMOS gate structure in the PMOS region;
wherein forming the metal boride above the gate dielectric in the PMOS region comprises;
forming a metal nitride above the gate dielectric in the PMOS region; and
introducing boron into the metal nitride to form the metal boride in the PMOS region.
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Abstract
Semiconductor devices and fabrication methods are provided, in which metal transistor gates are provided for MOS transistors. Metal boride is formed above a gate dielectric to create PMOS gate structures and metal nitride is formed over a gate dielectric to provide NMOS gate structures. The metal portions of the gate structures are formed from an initial starting material that is either a metal boride or a metal nitride, after which the starting material is provided with boron or nitrogen in one of the PMOS and NMOS regions through implantation, diffusion, or other techniques, either before or after formation of the conductive upper material, and before or after gate patterning. The change in the boron or nitrogen content of the starting material provides adjustment of the material work function, thereby tuning the threshold voltage of the resulting PMOS or NMOS transistors.
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Citations
30 Claims
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1. A method of fabricating PMOS and NMOS metal gate structures in a semiconductor device, the method comprising:
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forming a gate dielectric in PMOS and NMOS regions above a semiconductor body;
forming a metal nitride above the gate dielectric in the NMOS region;
forming a metal boride above the gate dielectric in the PMOS region;
patterning the metal nitride to form an NMOS gate structure in the NMOS region; and
patterning the metal boride to form a PMOS gate structure in the PMOS region;
wherein forming the metal boride above the gate dielectric in the PMOS region comprises;
forming a metal nitride above the gate dielectric in the PMOS region; and
introducing boron into the metal nitride to form the metal boride in the PMOS region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of fabricating PMOS and NMOS metal gate structures in a semiconductor device, the method comprising:
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forming a gate dielectric in PMOS and NMOS regions above a semiconductor body;
forming a metal nitride above the gate dielectric in the NMOS region;
forming a metal boride above the gate dielectric in the PMOS region;
patterning the metal nitride to form an NMOS gate structure in the NMOS region; and
patterning the metal boride to form a PMOS gate structure in the PMOS region;
wherein forming metal nitride above the gate dielectric in the NMOS region comprises;
forming metal boride above the gate dielectric in the NMOS region; and
introducing nitrogen into the metal boride to form the metal nitride in the PMOS region. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A method of fabricating PMOS and NMOS metal gate structures in a semiconductor device, the method comprising:
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forming a gate dielectric on PMOS and NMOS regions above a semiconductor body;
forming a starting material above the gate dielectric in both the NMOS region and the PMOS region, the starting material being a metal nitride or a metal boride;
changing the starting material in a first one of the NMOS region and the PMOS region such that a metal nitride is provided above the gate dielectric in the NMOS region and a metal boride is provided above the gate dielectric in the PMOS region;
patterning the metal nitride to form an NMOS gate structure in the NMOS region; and
patterning the metal boride to form a PMOS gate structure in the PMOS region. - View Dependent Claims (21, 22)
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23. A semiconductor device comprising:
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an NMOS transistor gate structure, the NMOS gate structure comprising a metal nitride structure and a gate dielectric between the metal nitride structure and a semiconductor body; and
a PMOS transistor gate structure, the PMOS gate structure comprising a metal boride structure and a gate dielectric between the metal boride structure and the semiconductor body, wherein the metal boride structure comprises a metal nitride material doped with boron. - View Dependent Claims (24, 25, 26, 27, 28)
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29. A semiconductor device comprising:
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an NMOS transistor gate structure, the NMOS gate structure comprising a metal nitride structure and a gate dielectric between the metal nitride structure and a semiconductor body; and
a PMOS transistor gate structure, the PMOS gate structure comprising a metal boride structure and a gate dielectric between the metal boride structure and the semiconductor body, wherein the metal nitride structure comprises a nitrided metal boride. - View Dependent Claims (30)
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Specification