Sacrificial mandrel structure with oxide pillars having different widths and resulting fins arrangements

An intermediate fin field effect transistor (FinFET) structure, comprising:

• a semiconductor substrate;
• a nitride layer directly on the semiconductor substrate;
• an oxide layer directly on the nitride layer;
• a sacrificial mandrel directly on the oxide layer, wherein the oxide layer is between the sacrificial mandrel and the nitride layer, and wherein the sacrificial mandrel has a width in the range of about 20 nm to about 400 nm, and wherein the sacrificial mandrel includes a sidewall portion doped with a p-type dopant;
• a first oxide pillar on a first side of the sacrificial mandrel and a second oxide pillar on the opposite side of the sacrificial mandrel, wherein the first oxide pillar has a width in the range of about 10 nm to about 60 nm, and the second oxide pillar has a width in the range of about 10 nm to about 30 nm, wherein the width of the second oxide pillar is less than the width of the first oxide pillar, and the first oxide pillar is in physical contact with the doped sidewall portion of the sacrificial mandrel;
• and
• a capping layer covering a top surface of the sacrificial mandrel including the doped sidewall portion, at least a portion of the first oxide pillar, and at least a portion of the second oxide pillar.