Gate structures and methods of manufacture

1. A method comprising:

forming an insulator layer on a substrate and a sacrificial layer on the insulator layer;

patterning the insulator layer and the sacrificial layer to form a plurality of dummy gate structures;

forming sidewall structures on sidewalls of the dummy gate structures;

removing the sacrificial layers from a first dummy gate structure and a second dummy gate structure to form a first trench and a second trench, respectively, defined by the sidewall structures;

removing the insulator layer forming a bottom portion of the second trench while protecting the insulator layer in the first trench;

forming a channel material on the substrate in the first trench while the insulator layer in the second trench acts as a mask in the second trench;

removing the insulator layer in the second trench after the channel material is formed; and

filling remaining portions of the first trench and the second trench with gate material to form a metal gate in each of the first trench and the second trench.

2. The method of claim 1 , wherein the channel material is material with high mobility of charge carriers.

3. The method of claim 1 , wherein the filling comprises:

forming an insulating material on the material with high mobility of charge carriers in the first trench and on the substrate in the second trench;

depositing a high-k dielectric material on the insulating layer in both the first trench and the second trench; and

depositing metal materials on the high-k dielectric material in both the first trench and the second trench.

4. The method of claim 3 , wherein the metal materials are tailored in one of the first trench and the second trench for a work function of the metal gate in the first trench and the second trench.

5. The method of claim 1 , further comprising:

forming a recess in the first trench, wherein:

the channel material is formed within the recess of the first trench, and the filling comprises:

forming an insulating material on the channel material within the recess of the first trench and on the substrate in the second trench;

depositing a high-k dielectric material on the insulating material in both the first trench and the second trench; and

depositing metal materials on the high-k dielectric material in both the first trench and the second trench.

6. The method of claim 5 , wherein the insulating material, high-k dielectric material and metal materials are deposited in the first trench and the second trench during same processing steps.

7. The method of claim 5 , wherein the metal materials are tailored in one of the first trench and the second trench for a work function.

8. The method of claim 1 , wherein the channel material is formed after the removing the sacrificial layers from the first dummy gate structure and the second dummy gate structure.

9. A method, comprising:

forming dummy gate structures on a substrate;

forming sidewall structures on sidewalls of the dummy gate structures;

removing the dummy gate structures to form a plurality of trenches, defined by the sidewall structures;

forming a channel material in a first trench and a second trench;

forming a thick oxide layer on the channel material in the first trench and the second trench, and on the substrate in a third trench and a fourth trench; and

removing the thick oxide layer from the second trench to expose the channel material and the fourth trench to expose the substrate;

forming a thin oxide layer on the channel material in the second trench and the substrate in the fourth trench; and

filling remaining portions of the first trench, the second trench, the third trench and the fourth trench with gate material, wherein:

the filling comprises:

forming an insulating material in the first trench, the second trench, the third trench and the fourth trench;

depositing a high-k dielectric material on the insulating material in the first trench, the second trench, the third trench and the fourth trench; and

depositing metal materials on the high-k dielectric material in the he first trench, the second trench, the third trench and the fourth trench.

10. The method of claim 9 , wherein:

the first trench forms a thick oxide pFET device;

the second trench forms a thin oxide pFET device;

the third trench forms a thick oxide nFET device; and

the fourth trench forms a thin oxide nFET device.

11. The method of claim 9 , wherein the forming the channel material comprises forming the channel material in the third trench and the fourth trench.

12. The method of claim 11 , wherein the channel material in the third trench and the fourth trench are removed prior to the forming of the thick oxide layer.

13. The method of claim 11 , wherein the metal materials are tailored in one of the first trench and the second trench for a designed work function.