Fin field effect transistors
The disclosure relates to a fin field effect transistor (FinFET). An exemplary structure for a FinFET comprises a substrate comprising a major surface; a plurality of first trenches having a first width and extending downward from the substrate major surface to a first height, wherein a first space between adjacent first trenches defines a first fin; and a plurality of second trenches having a second width less than first width and extending downward from the substrate major surface to a second height greater than the first height, wherein a second space between adjacent second trenches defines a second fin.
1. A fin field effect transistor (FinFET) comprising:
a substrate comprising a major surface;
a plurality of first trenches having a first width and a first depth, each first trench of the plurality of first trenches extending downward from the substrate major surface to a first height, wherein a first space between adjacent first trenches defines a first fin;
a plurality of second trenches having a second width and a second depth, the second width less than first width, each second trench of the plurality of second trenches extending downward from the substrate major surface to a second height greater than the first height, wherein a second space between adjacent second trenches defines a second fin;
a first isolation structure partially filling each first trench of the plurality of first trenches;
a second isolation structure partially filling each second trench of the plurality of second trenches, wherein a difference between a height of the first isolation structure and the first depth is substantially equal to a difference between a height of the second isolation structure and the second depth;
wherein the first fin has a third width; and
the second fin has a fourth width that is different from the third width.
2. The FinFET of claim 1 , wherein a ratio of the second width to the first width is from about 0.1 to about 0.5.
3. The FinFET of claim 1 , wherein a ratio of the second height to the first height is from about 1.05 to about 1.25.
4. The FinFET of claim 1 , wherein the second space is equal to or less than the first space.
5. The FinFET of claim 1 , wherein a ratio of the second space to the first space is from about 0.5 to about 1.
6. The FinFET of claim 1 , the first fin comprises substantially vertical sidewalls.
7. The FinFET of claim 1 , wherein the second fin comprises tapered sidewalls.
8. A semiconductor device comprising:
a substrate comprising a major surface;
a first Fin field effect transistor (FinFET) comprising:
a plurality of first trenches having a first width and a first depth, each first trench of the plurality of first trenches extending downward from the substrate major surface to a first height, wherein a first space between adjacent first trenches defines a first fin;
a first gate dielectric on a top surface and sidewalls of the first fin; and
a first gate electrode on the first gate dielectric;
a second FinFET comprising:
a plurality of second trenches having a second width and a second depth, the second width less than first width, each second trench of the plurality of second trenches extending downward from the substrate major surface to a second height greater than the first height, wherein a second space between adjacent second trenches defines a second fin;
a second gate dielectric on a top surface and sidewalls of the second fin;
a second gate electrode on the second gate dielectric;
wherein the first fin has a third width;
the second fin has a fourth width that is different from the third width: and
a first isolation structure partially filling each first trench of the plurality of first trenches; and
a second isolation structure partially filling each second trench of the plurality of second trenches, wherein a difference between a height of the first isolation structure and the first depth is substantially equal to a difference between a height of the second isolation structure and the second depth.
9. The semiconductor device of claim 8 , wherein a ratio of the second width to the first width is from about 0.1 to about 0.5.
10. The semiconductor device of claim 8 , wherein a ratio of the second height to the first height is from about 1.05 to about 1.25.
11. The semiconductor device of claim 8 , wherein the second space is equal to or less than the first space.
12. The semiconductor device of claim 8 , wherein a ratio of the second space to the first space is from about 0.5 to about 1.
13. The semiconductor device of claim 8 , the first fin comprises substantially vertical sidewalls.
14. The semiconductor device of claim 8 , wherein the second fin comprises tapered sidewalls.
15. The semiconductor device of claim 8 , wherein the first fin is a portion of an I/O device and the second fin is a portion of a core device.
16. A semiconductor device comprising:
a substrate comprising a first region and a second region;
a plurality of first trenches in the first region of the substrate, each of the plurality of first trenches having a first depth;
at least one first fin between adjacent first trenches of the plurality of first trenches;
a plurality of second trenches in the second region of the substrate, each of the plurality of second trenches having a second depth less than the first depth;
at least one second fin between adjacent second trenches of the plurality of second trenches;
at least one third fin between one second trench of the plurality of second trenches and one first trench of the plurality of first trenches, wherein a height of a first sidewall of the at least one third fin is equal to the first depth, and a height of a second sidewall of the at least one third fin opposite the first sidewall is equal to the second depth;
wherein the first fin has a third width; and
the second fin has a fourth width that is different from the third width;
a first isolation structure partially filling each first trench of the plurality of first trenches; and
a second isolation structure partially filling each second trench of the plurality of second trenches, wherein a difference between a height of the first isolation structure and the first depth is substantially equal to a difference between a height of the second isolation structure and the second depth.
17. The semiconductor device of claim 16 , wherein a ratio of a width of the at least one third fin to a width of the at least one first fin ranges from 0.9 to 1.1.
18. The semiconductor device of claim 16 , further comprising:
a first gate structure over the at least one first fin and the at least one third fin;
a second gate structure over the at least one second fin; and
an isolation structure separating the first gate structure from the second gate structure.
19. The semiconductor device of claim 16 , wherein the difference between a height of the first isolation feature and the first depth ranges from about 300 Angstroms (Å) to about 1000 Å.
20. The semiconductor device of claim 16 , wherein the substrate is doped.