Self-aligned trench MOSFET contacts having widths less than minimum lithography limits
Semiconductor devices made by forming hard mask pillars on a surface of a substrate, forming sacrificial spacers on a first side of each hard mask pillar and a second side of each hard mask pillar. The open gaps may be formed between adjacent sacrificial spacers. The semiconductor devices may also be formed by etching the hard mask pillars to form pillar gaps, etching gate trenches into the substrate through the open gaps and the pillar gaps, forming a gate electrode within the gate trenches, implanting channels and sources in the substrate below the sacrificial spacers, forming an insulator layer around the sacrificial spacers, etching the sacrificial spacers to form contact trenches within the substrate, and filling the contact trenches with a conductive material to form contacts.
1. A method of fabricating a semiconductor device on a substrate, comprising:
forming hard mask pillars on a surface of the substrate;
forming sacrificial spacers on a first side of each hard mask pillar and a second side of each hard mask pillar, wherein open gaps are formed between adjacent sacrificial spacers;
etching the hard mask pillars to form pillar gaps;
etching gate trenches into the substrate through the open gaps and the pillar gaps;
forming a gate electrode within the gate trenches;
implanting channels and sources in the substrate below the sacrificial spacers;
forming an insulator layer around the sacrificial spacers;
etching the sacrificial spacers to form contact trenches within the substrate; and
filling the contact trenches with a conductive material to form contacts.
2. The method of claim 1 , wherein forming the hard mask pillars comprises thinning the hard mask pillars through etching.
3. The method of claim 1 , comprising cleaning the substrate before forming the sacrificial spacers.
4. The method of claim 1 , comprising self-aligning the contact trenches and the gate trenches.
5. The method of claim 1 , comprising etching each sacrificial spacer before implanting the channels and the sources in the substrate.
6. The method of claim 1 , comprising polishing each sacrificial spacer before etching the gate trenches.
7. The method of claim 1 , comprising:
forming a layer of filler material within the open gaps and above the hard mask pillars; and
polishing the hard mask pillars, the sacrificial spacers, and the filler material, or any combination thereof.
8. The method of claim 1 , wherein implanting the channels and the sources comprises implanting a dopant at an angle between 3 and 10 degrees.
9. The method of claim 1 , comprising annealing the insulator layer before etching the sacrificial spacers.
10. The method of claim 1 , comprising etching the sources after etching the sacrificial spacers, wherein the contacts contact the channels.
11. The method of claim 1 , wherein forming the hard mask pillars comprises KrF scanner lithography processing or ArF scanner lithography processing.