Method for forming uniaxially strained devices
View Patent ↗A method for making a semiconductor device is provided herein. In accordance with the method, a semiconductor structure is provided which comprises a substrate ( 201 ) with a gate structure ( 209 ) disposed thereon, wherein the gate structure comprises a gate electrode ( 227 ) and at least one spacer structure ( 215, 217 ), and wherein the substrate comprises a first semiconductor material. A first trench ( 231 ) is created in the substrate adjacent to the gate structure through the use of a first etch. The gate electrode is then etched with a second etch. Preferably, the minimum cumulative reduction in thickness of the gate electrode from the first and second etches is d g , the maximum depth of the first and second trenches after the first and second etches is d t , and d g ≧d t .
1. A method for making a semiconductor device, comprising:
providing a semiconductor structure comprising a substrate with a gate structure disposed thereon, wherein the gate structure comprises a gate electrode and at least one spacer structure, and wherein the substrate comprises a first semiconductor material;
creating a first trench in the substrate through the use of a first etch, the first trench being adjacent to the gate structure; and etching the gate electrode with a second etch, and wherein the first etch is a dry etch, and wherein the second etch is a wet etch.
2. The method of claim 1 , wherein the minimum cumulative reduction in thickness of the gate electrode from the first and second etches is d g , wherein the maximum depth of the first trench after the first and second etches is d t , and wherein d g ≧d t .
3. The method of claim 1 , wherein the first etch primarily etches the substrate, and wherein the second etch primarily etches the gate electrode.
4. The method of claim 1 , further comprising:
epitaxially growing a second semiconductor material in the first trench.
5. The method of claim 4 , wherein the step of epitaxially growing the second semiconductor material on the first semiconductor material also results in the growth of the second semiconductor material on the gate electrode.
6. The method of claim 4 , wherein the maximum height of the gate electrode after the growth of the second semiconductor material is not greater than the maximum height of the gate electrode prior to the first etch.
7. The method of claim 4 , wherein the second semiconductor material has a larger lattice spacing than the first semiconductor material.
8. The method of claim 7 , wherein the first semiconductor material is silicon, and wherein the second semiconductor material is SiGe.
9. The method of claim 1 , further comprising depositing a barrier layer of a first semiconductor material in the first trench.
10. The method of claim 1 , wherein the second etch is conducted in an epitaxial chamber.
11. The method of claim 10 , wherein the second etch comprises treatment with hot gaseous HCl.
12. The method of claim 1 , wherein the first etch also creates a second trench adjacent to the gate structure.
13. The method of claim 1 , wherein the gate electrode is covered with an etch mask during the first etch.
14. The method of claim 1 , wherein the first trench is covered with an etch mask during the second etch.
15. A method for making a semiconductor device, comprising:
providing a semiconductor device comprising a substrate with a gate structure disposed thereon, the gate structure comprising a gate electrode and at least one spacer structure;
creating first and second trenches in the substrate on first and second sides of the gate electrode, respectively, through the use of a first etch; and
etching the gate electrode with a second etch;
wherein the minimum cumulative reduction in thickness of the gate electrode from the first and second etches is d g , wherein the maximum depth of the first and second trenches after the first and second etches is d t , and wherein d g ≧d t .
16. The method of claim 15 , wherein the substrate comprises a first semiconductor material, and further comprising epitaxially growing a second semiconductor material in the first trench.
17. The method of claim 16 , wherein the step of epitaxially growing the second semiconductor material on the first semiconductor material also results in the growth of the second semiconductor material on the gate electrode.
18. The method of claim 15 , wherein the maximum height of the gate electrode after the growth of the second semiconductor material is not greater than the maximum height of the gate electrode prior to the first etch.
19. The method of claim 16 , wherein the first etch is a dry etch, and wherein the second etch comprises treatment with gaseous HCl in an epitaxial chamber.