Self-aligned multiple gate transistor formed on a bulk substrate
Three-dimensional transistors in a bulk configuration may be formed on the basis of gate openings or gate trenches provided in a mask material. Hence, self-aligned semiconductor fins may be efficiently patterned in the underlying active region in a portion defined by the gate opening, while other gate openings may be efficiently masked, in which planar transistors are to be provided. After patterning the semiconductor fins and adjusting the effective height thereof, the further processing may be continued on the basis of process techniques that may be commonly applied to the planar transistors and the three-dimensional transistors.
1. A method, comprising:
forming a first mask layer above a semiconductor layer of a semiconductor device, said first mask layer comprising a gate opening that defines a lateral size and position of a gate electrode;
forming a second mask layer in said gate opening, said second mask layer comprising a plurality of mask features defining a lateral size and position of a plurality of fins to be formed in said semiconductor layer;
performing an etch process using said first and second mask layers to form said fins in a portion of said semiconductor layer and to define a space between said fins in said semiconductor layer, said space having sidewalls;
removing said second mask layer;
after removing said second mask layer, forming a dielectric material in said gate opening so as to adjust an electrically effective height of said plurality of fins by forming said dielectric material above said first mask layer and within said gate opening and removing a first excess portion of said dielectric material by using said first mask layer as a stop material, wherein removing the first excess portion of said dielectric material comprises performing a chemical mechanical planarization (CMP) process and using said first mask layer as a CMP stop layer;
performing a single process operation to form a gate insulation layer on said fins and on said sidewalls of said space; and
forming a gate electrode in said gate opening above said gate insulation layer.
2. The method of claim 1 , wherein forming said first mask layer comprises forming a first sub-layer above said semiconductor layer and forming a second sub-layer on said first sub-layer, wherein said second sub-layer has an increased stop capability compared to said first sub-layer with respect to said CMP process.
3. The method of claim 2 , wherein said second sub-layer is formed so as to comprise platinum.
4. The method of claim 1 , wherein forming said dielectric material further comprises removing a second excess portion by performing an etch process so as to expose a target height of said plurality of fins.
5. The method of claim 1 , further comprising forming drain and source regions in said semiconductor layer laterally adjacent to said gate electrode after removal of said first mask layer.
6. The method of claim 4 , wherein forming said gate electrode comprises forming at least one of an electrode material and a placeholder material above said dielectric material and forming a mask material on said electrode material.
7. The method of claim 1 , further comprising forming a cavity in said semiconductor layer adjacent to said gate electrode after removing said first mask layer and filling said cavity with a strain-inducing semiconductor material.
8. The method of claim 1 , wherein forming said first mask layer comprises forming said first mask layer so as to receive a second gate opening that exposes a second portion of said semiconductor layer and forming a second gate electrode structure in said second gate opening without forming fins in said second portion of the semiconductor layer.
9. A method of forming a semiconductor device, the method comprising:
forming a first gate opening and a second gate opening in a first mask layer that is formed above a semiconductor layer, said first and second gate openings defining a lateral position and size of a first gate electrode structure and a second gate electrode structure, respectively;
forming a plurality of fins in said semiconductor layer through said first gate opening while masking said second gate opening;
forming a first gate electrode structure in said first gate opening, said first gate electrode structure being in contact with said plurality of fins;
adjusting an electrically effective height of said plurality of fins formed through said first gate opening by forming a dielectric material in said first and second gate openings with a predefined height level, wherein forming said dielectric material comprises:
depositing said dielectric material above said mask layer and in said first and second gate openings;
performing a planarization process using said mask layer as a stop layer; and
removing an excess portion of said dielectric material in said first and second gate openings by performing an etch process;
forming a second gate electrode in said second gate opening; and
forming drain and source regions in said semiconductor layer adjacent to said first and second gate electrode structures.
10. The method of claim 9 , further comprising forming a strain-inducing semiconductor material in said drain and source regions after removing said mask layer.
11. The method of claim 10 , wherein forming said strain-inducing semiconductor material in said drain and source regions comprises performing at least one of an epitaxial growth process and a stress memorization process.
12. A method, comprising:
forming a first mask layer above a semiconductor layer of a semiconductor device, said first mask layer comprising a gate opening that defines a lateral size and position of a gate electrode;
forming a second mask layer in said gate opening, said second mask layer comprising a plurality of mask features defining a lateral size and position of a plurality of fins to be formed in said semiconductor layer;
performing an etch process using said first and second mask layers to form said fins in a portion of said semiconductor layer;
forming a dielectric material in said gate opening after forming said plurality of fins so as to adjust an electrically effective height of said plurality of fins, wherein forming said dielectric material comprises forming said dielectric material above said first mask layer and within said gate opening and removing a first excess portion of said dielectric material by performing a chemical mechanical planarization (CMP) process using said first mask layer as a CMP stop layer; and
forming a gate electrode structure in said gate opening after removal of said second mask layer, said gate electrode structure comprising said gate electrode and connecting to said plurality of fins.
13. The method of claim 12 , wherein forming said first mask layer comprises forming a first sub-layer above said semiconductor layer and forming a second sub-layer on said first sub-layer, wherein said second sub-layer has an increased stop capability compared to said first sub-layer with respect to said CMP process.
14. The method of claim 13 , wherein said second sub-layer is formed so as to comprise platinum.