Bulk finFET with controlled fin height and high-K liner
A method of forming a semiconductor device that includes forming a material stack on a semiconductor substrate, the material stack including a first dielectric layer on the substrate, a second dielectric layer on the first dielectric layer, and a third dielectric layer on the second dielectric layer, wherein the second dielectric layer is a high-k dielectric. Openings are formed through the material stack to expose a surface of the semiconductor substrate. A semiconductor material is formed in the openings through the material stack. The first dielectric layer is removed selectively to the second dielectric layer and the semiconductor material. A gate structure is formed on a channel portion of the semiconductor material. In some embodiments, the method may provide a plurality of finFET or trigate semiconductor device in which the fin structures of those devices have substantially the same height.
1. A method of forming a semiconductor device comprising:
forming a material stack on a semiconductor substrate, the material stack including a first dielectric layer on the semiconductor substrate, a second dielectric layer on the first dielectric layer, and a third dielectric layer on the second dielectric layer, wherein the second dielectric layer is a high-k dielectric;
forming openings through the material stack to expose a surface of the semiconductor substrate;
forming a doped semiconductor material in the openings through the material stack, wherein the doped semiconductor material extends from the surface of the semiconductor substrate past an interface between the first dielectric layer and the second dielectric layer;
forming an intrinsic semiconductor material in the openings on the doped semiconductor material;
removing the third dielectric layer selective to the second dielectric layer, the intrinsic semiconductor material and the doped semiconductor material; and
forming a gate structure on a channel portion of the intrinsic semiconductor material.
2. The method of claim 1 , wherein at least one of the first dielectric layer and the third dielectric layer comprises an oxide, nitride or oxynitride, and the second dielectric layer comprises a hafnium containing dielectric.
3. The method of claim 1 , wherein the forming of the openings through the material stack comprises spacer image transfer and selective etching.
4. The method of claim 1 , wherein continuous portions of the first dielectric layer separate adjacent portions of the doped semiconductor material.
5. The method of claim 1 , wherein a first surface of the doped semiconductor material that is opposite a second surface of the doped semiconductor material that is in contact with the semiconductor substrate is coplanar with an interface between the third dielectric layer and the second dielectric layer, or is present between the interface between the third dielectric layer and the second dielectric layer and the interface between the first dielectric layer and the second dielectric layer.
6. The method of claim 1 , wherein the intrinsic semiconductor material is formed using an epitaxial deposition process, and each of the doped semiconductor material is formed using epitaxial deposition and an in-situ deposition process.
7. The method of claim 1 , wherein the forming of the intrinsic semiconductor material comprises:
filling the opening with the doped intrinsic semiconductor material, wherein an overfill portion extends onto a surface of the third dielectric layer that is adjacent to the opening; and
planarizing to remove the overfill portion of the intrinsic semiconductor material.
8. The method of claim 1 , wherein the removing of the third dielectric layer selective to the second dielectric layer, the doped semiconductor material and the intrinsic semiconductor material comprises a selective etch process, wherein the selective etch process comprises an etch chemistry of hot phosphoric acid.
9. The method of claim 1 , wherein the forming of the gate structure on the channel portion of the intrinsic semiconductor material comprises forming a gate dielectric on sidewall and upper surfaces of the intrinsic semiconductor material and forming a gate conductor on the gate dielectric, wherein the semiconductor device is a tri-gate semiconductor device.
10. The method of claim 1 , further comprising oxidizing an upper surface of the intrinsic semiconductor material to provide a dielectric cap, and wherein the forming of the gate structure on the channel portion of the intrinsic semiconductor material comprises forming a gate dielectric on sidewall of the intrinsic semiconductor material and on the dielectric cap, and forming a gate conductor on the gate dielectric, wherein the semiconductor device is a finFET semiconductor device.