Pitch split patterning for semiconductor devices

A method for forming fins of a semiconductor device, the method comprising:

• forming a first hardmask on a semiconductor substrate;
• forming a sacrificial layer on the first hardmask;
• forming a second hardmask on the sacrificial layer;
• removing portions of the second hardmask and the sacrificial layer to form a sacrificial mandrel on the first hardmask;
• forming sacrificial spacers adjacent to the sacrificial mandrel;
• doping the sacrificial spacers adjacent to the sacrificial mandrel with a dopant
• forming a second sacrificial layer on exposed portions of the first hardmask and the second hardmask;
• planarizing the second sacrificial layer to expose portions of the sacrificial spacers and the first hardmask;
• annealing to drive the dopant from the sacrificial spacers into an adjacent region of the sacrificial mandrel underlying a portion of the second hardmask to form a first doped region and into an adjacent region of the second sacrificial layer to form a second doped region;
• removing the second hardmask;
• removing the sacrificial spacers to expose a portion of the first hardmask;
• removing undoped portions of the sacrificial mandrel and the second sacrificial layer to further expose portions of the first hardmask;
• removing exposed portions of the first hardmask to expose portions of the semiconductor substrate;
• and
• removing exposed portions of the semiconductor substrate to form fins.

A method for forming fins of a semiconductor device, the method comprising:

• forming a first hardmask on a semiconductor substrate;
• forming a sacrificial layer on the first hardmask;
• forming a second hardmask on the sacrificial layer;
• removing portions of the second hardmask and the sacrificial layer to form a sacrificial mandrel on the first hardmask;
• forming sacrificial spacers that include a silicate material adjacent to the sacrificial mandrel;
• doping the sacrificial spacers adjacent to the sacrificial mandrel with a dopant
• forming a second sacrificial layer on exposed portions of the first hardmask and the second hardmask;
• removing portions of the second sacrificial layer to expose portions of the spacers and the first hardmask;
• annealing to drive the dopant from the sacrificial spacers into an adjacent region of the sacrificial mandrel underlying a portion of the second hardmask to form a first doped region, and into an adjacent region of the second sacrificial layer to form a second doped region;
• removing the second hardmask;
• removing the sacrificial spacers to expose a portion of the first hardmask;
• removing undoped portions of the sacrificial mandrel and the second sacrificial layer to further expose portions of the first hardmask;
• removing exposed portions of the first hardmask to expose portions of the semiconductor substrate;
• and
• removing exposed portions of the semiconductor substrate to form fins.