Semiconductor devices with extended active regions
View Patent ↗A method of making a semiconductor device is achieved in and over a semiconductor layer. A trench is formed adjacent to a first active area. The trench is filled with insulating material. A masking feature is formed over a center portion of the trench to expose a first side of the trench between a first side of the masking feature and the first active area. A step of etching into the first side of the trench leaves a first recess in the trench. A first epitaxial region is grown in the first recess to extend the first active area to include the first recess and thereby form an extended first active region.
1. A method of forming a planar semiconductor device in and over a semiconductor layer, comprising:
forming a trench adjacent to a first active area;
filling the trench with insulating material;
forming a masking feature over a center portion of the trench to expose a first side of the trench between a first side of the masking feature and the first active area;
etching into the first side of the trench to leave a first recess in the trench; and
growing a first epitaxial region in the first recess, wherein the first epitaxial region completely fills the first recess to extend the first active area to include the first recess and thereby form an extended first active region.
2. The method of claim 1 , wherein the first active area has a first width extending in a first direction, further comprising:
forming planar transistor over and in the extended first active region having a gate over a channel running in the first direction wherein the planar transistor has a channel width greater than the first width.
3. The method of claim 1 , further comprising chemical mechanical polishing the extended first active area.
4. The method of claim 3 , wherein the first active area has a first width extending in a first direction, further comprising:
forming, after the step of chemical mechanical polishing, a planar transistor over and in the extended first active region having a gate over a channel running in the first direction wherein the planar transistor has a channel width greater than the first width.
5. The method of claim 1 further comprising trimming the masking feature prior to the step of etching.
6. The method of claim 5 , wherein the step of trimming is further characterized as comprising ashing.
7. The method of claim 1 , wherein:
the step of forming a trench is further characterized by the trench being between the first active area and a second active area;
the step of forming the masking feature is further characterized as exposing a second side of the trench between a second side of the masking feature and the second active area;
the step of etching is further characterized as etching into the second side of the trench to leave a second recess in the trench; and
the step of growing is further characterized by growing a second epitaxial region in the second recess, wherein the second epitaxial region completely fills the second recess to extend the second active area to include the second recess and thereby form an extended second active region.
8. The method of claim 7 , further comprising chemical mechanical polishing the extended first active area and the extended second active area.
9. The method of claim 8 , further comprising:
forming a gate, after the step of chemical mechanical polishing, extending over the first extended active area and the second active area including over the first epitaxial region and the second epitaxial region.
10. The method of claim 9 , wherein the step of forming the masking feature is further characterized by the masking feature comprising photoresist, the method further comprising trimming the photoresist before the step of etching.
11. A method of forming a planar semiconductor device, comprising:
providing a semiconductor substrate;
forming a trench around an active region that defines a boundary of the active region;
filling the trench with insulating material to form an isolation region;
forming a masking feature over the isolation region, wherein the masking feature has an edge spaced from the active region to provide an exposed region of the isolation region between the edge of the masking feature and the active region;
etching into the exposed region to form a recess;
filling the recess with semiconductor material, wherein the semiconductor material completely fills the recess to form an extended active region as a combination of the recess filled with semiconductor material and the active region; and
chemical mechanical polishing the extended active region.
12. The method of claim 11 , further comprising:
trimming the mask feature prior to the step of etching.
13. The method of claim 11 , further comprising forming a gate over the extended active region.
14. The method of claim 13 , wherein the step of forming the gate is further characterized by the gate passing over the recess filled with semiconductor material.
15. The method of claim 11 , wherein the step of forming the masking feature is further characterized by the exposed region extending completely around the active area.
16. The method of claim 11 , further comprising:
forming a planar transistor in and over the active region, the planar transistor having a gate that crosses the recess filled with semiconductor material in two different locations.
17. The method of claim 11 , wherein the step of completely filling the recess is further characterized as epitaxially growing the semiconductor material.