Method of making a dual strained channel semiconductor device
View Patent ↗A method of forming a semiconductor device includes forming on a substrate mandrels made from a semiconductor material. A semiconductor material having a lattice constant that is different than the mandrel semiconductor material is deposited onto sidewalls of the mandrels to form strained semiconductor layers. The mandrels are at least partially removed to form free-standing or partially-supported fins that include the strained semiconductor layers. The strained semiconductor layers may include tensile silicon or compressive silicon germanium, which can be used to form a dual strained channel semiconductor device.
1. A method of forming a semiconductor device comprising:
providing a material stack comprising, from bottom to top, a semiconductor substrate and a base semiconductor layer of a strained semiconductor material;
forming a plurality of mandrels by etching an upper portion of the base semiconductor layer, wherein the mandrels are located on a remaining unetched portion of the base semiconductor layer, and wherein each mandrel and the remaining unetched portion of the semiconductor base layer comprise a semiconductor material that is relaxed relative to the strained semiconductor material of the base semiconductor layer prior to the etching;
depositing a first semiconductor material directly on a pair of opposing semiconductor sidewalls of the mandrels and within a first region of the semiconductor substrate to form first strained semiconductor material layers directly on the opposing semiconductor sidewalls of the mandrels within the first region; and
removing the mandrels to form semiconductor fins comprising the first strained semiconductor material layers.
2. The method of claim 1 , wherein the first strained semiconductor material layers comprise tensile silicon.
3. The method of claim 1 , wherein the first strained semiconductor material layers comprise compressive silicon germanium.
4. The method of claim 1 , further comprising
depositing a second semiconductor material directly on a pair of opposing semiconductor sidewalls of the mandrels within a second region of the semiconductor substrate to form second strained semiconductor material layers directly on the opposing semiconductor sidewalls within the second region, wherein the first strained semiconductor material layers are tensile and the second strained semiconductor material layers are compressive.
5. The method of claim 4 , wherein the first strained semiconductor material layers comprise silicon and the second strained semiconductor material layers comprise silicon germanium.
6. The method of claim 5 , wherein the silicon germanium comprises 50 to 75 atomic percent germanium.
7. The method of claim 4 , wherein the removing the mandrels in the second region provides semiconductor fins comprising the second strained semiconductor material layers.
8. The method of claim 1 , wherein the strained semiconductor material of the base semiconductor layer comprises silicon germanium having 25 to 50 atomic percent germanium.
9. The method of claim 1 , further comprising depositing a dielectric layer on the remaining unetched portion of the base semiconductor layer prior to depositing the first semiconductor material.
10. The method of claim 1 , further comprising depositing a hard mask on a top surface of the base semiconductor layer prior to forming the mandrels.
11. The method of claim 1 , further comprising depositing a hard mask on a top surface of the base semiconductor layer prior to the forming the mandrels.
12. A method of forming a semiconductor device comprising:
providing a material stack comprising, from bottom to top, a semiconductor substrate and a base semiconductor layer of a strained semiconductor material;
forming a plurality of mandrels by etching into an upper portion of the base semiconductor layer, wherein each mandrel is present on an unetched portion of the base semiconductor layer, and wherein each mandrel and the remaining unetched portion of the semiconductor base layer comprise a semiconductor material that is relaxed relative to the strained semiconductor material of the base semiconductor layer prior to the etching;
depositing a first semiconductor material directly on a pair of opposing semiconductor sidewalls of each of the mandrels within a first region of the semiconductor substrate to form first strained semiconductor material layers directly on the opposing semiconductor sidewalls of each of the mandrels within the first region;
depositing a second semiconductor material directly on a pair of opposing semiconductor sidewalls of each of the mandrels within a second region of the semiconductor substrate to form second strained semiconductor material layers directly on the opposing semiconductor sidewalls of each of the mandrels within the second region; and
removing the mandrels to form semiconductor fins comprising the first and second strained semiconductor material layers.
13. The method of claim 12 , wherein the first strained semiconductor material layers comprise tensile silicon and the second strained semiconductor material layers comprise compressive silicon germanium.
14. The method of claim 12 , wherein the second strained semiconductor material layers comprise 50 to 75 atomic percent germanium.
15. The method of claim 12 , wherein the mandrels comprise silicon germanium having 25 to 50 atomic percent germanium.
16. The method of claim 12 , further comprising depositing a dielectric layer within a gap located between each of the mandrels prior to depositing the first and second semiconductor materials.