Method of implanting a non-dopant atom into a semiconductor device
View Patent ↗A method of forming an isolation trench structure is disclosed, the method includes forming an isolation trench in a semiconductor body associated with an isolation region, and implanting a non-dopant atom into the isolation trench, thereby forming a region to modify the halo profile in the semiconductor body. Subsequently, the isolation trench is filled with a dielectric material.
1. A method of fabricating a semiconductor structure, the method comprising:
etching a trench with sidewalls and a bottom surface in a semiconductor body;
implanting carbon and/or nitrogen ions into the trench, wherein the carbon and/or nitrogen ions are implanted in four equal parts separated by 90 degrees around a direction normal to the semiconductor body;
filling the trench with a dielectric to form a trench isolation region; and
doping to form an active region disposed in the semiconductor body, wherein the trench isolation region is formed around the active region.
2. The method of claim 1 , wherein the semiconductor body comprises a semiconductor substrate.
3. The method of claim 1 , wherein the carbon and/or nitrogen ions are implanted at an angle not normal to the bottom surface of the trench.
4. The method of claim 3 , wherein the angle is greater than 10 degrees.
5. The method of claim 1 , wherein a change in dopant profile is localized around the edges of the trench.
6. The method of claim 1 , wherein addition of the angled carbon and/or nitrogen implant results in a matching of device electrostatics between a narrow width transistor to that of a transistor with a larger width.
7. The method of claim 6 , wherein the matching of device electrostatics means a matching of threshold voltage.
8. The method of claim 6 , wherein the narrow width transistor has an active width less than 300 nm.
9. The method of claim 1 , wherein a trench liner is deposited over the sidewalls and the bottom surface of the trench prior to the carbon and/or nitrogen implant.
10. The method of claim 1 , wherein the active region comprises part of a MOS transistor.
11. A method of fabricating a semiconductor structure, the method comprising:
providing an active region by etching isolation trenches in a semiconductor body, each isolation trench having sidewalls and a bottom surface;
implanting non-dopant ions into the trenches at an angle not normal to the bottom surface; the non-dopant ions forming a non-dopant distribution region spatially symmetric around the isolation trenches;
filling the trench with a dielectric to form a trench isolation region;
implanting halo atoms; and
doping to structure the active region disposed in the semiconductor body, wherein a location of a peak concentration of the non-dopant atoms match the location of a peak concentration of halo atoms.
12. The method of claim 11 , wherein the non-dopant distribution region decays with distance from the trench.
13. The method of claim 11 , wherein the non-dopant ions are implanted in four equal parts separated by 90 degrees around a direction normal to the semiconductor surface.
14. The method of claim 11 , wherein non-dopant atoms comprise nitrogen, carbon, fluorine, silicon, or germanium.
15. The method of claim 11 , wherein the angle not normal to the semiconductor surface comprises an angle from about 10 degrees to about 45 degrees from a direction normal to the semiconductor surface.
16. The method of claim 11 , wherein a majority of the non-dopant atoms is placed away from a periphery of trench corners.