Precise Critical Dimension Control Using Bilayer ALD

A processing method comprising:

• providing a substrate with a patterned photoresist thereon, the photoresist comprising a plurality of photoresist features, each photoresist feature having at least one sidewall, a top and a width;
• depositing a first layer of a spacer film by sequential exposure of the photoresist to a first precursor and a first plasma, each exposure to the first plasma occurring under a first process condition, wherein depositing the first layer results in a decrease in the width of the plurality of photoresist features;
• depositing a second layer of a spacer film by sequential exposure of the photoresist to a second precursor and a second plasma to form a spacer film, each exposure to the second plasma occurring under a second process condition different from the first process condition, wherein depositing the second layer results in substantially no change in the width of the photoresist features;
• etching the spacer film to remove substantially all of the spacer film from the top of the photoresist features without removing substantially any of the spacer film from the sidewalls of the photoresist features;
• removing the patterned photoresist to expose the substrate beneath the photoresist features and leave the spacer film from the sidewalls of the photoresist features;
• and
• etching the exposed substrate to form adjacent pairs of first features comprising the substrate material, the adjacent pairs of first features having adjacent critical dimension and pair critical dimension.

A processing method comprising:

• positioning a substrate having a photoresist with photoresist features thereon in a processing chamber, each of the photoresist features having a top, sidewalls and a width;
• depositing up to ten PE ALD layers of a spacer film, each layer deposited by a first PE ALD process to decrease the width of the photoresist features, the first PE ALD process comprising,
• exposing the substrate to a first process gas in a first processing region of the processing chamber, the first process gas comprising a silicon precursor,
• laterally moving the substrate through a gas curtain to a second process region in the processing chamber,
• exposing the substrate to a second process gas in the second process region for a first exposure time, the second process gas comprising a plasma;
• depositing additional spacer film by repeating a second PE ALD process to form a spacer film having a total thickness in the range of about 10 nm to about 50 nm, the second PE ALD process comprising,
• exposing the substrate to a third process gas in a third processing region, the third process gas comprising a silicon precursor,
• laterally moving the substrate through a gas curtain to a fourth process region in the processing chamber,
• exposing the substrate to a fourth process gas in the fourth process region for a second exposure time, the second process gas comprising a plasma, the second exposure time being shorter than the first exposure time;
• etching the spacer film to remove substantially all of the spacer film from the top of the photoresist features without removing substantially any of the spacer film from the sidewalls of the photoresist features;
• removing the photoresist to expose the substrate beneath the photoresist features and leave the spacer film from the sidewalls of the photoresist features;
• and
• etching the exposed substrate to form adjacent pairs of first features comprising the substrate material, the adjacent pairs of first features having adjacent critical dimension and pair critical dimension, the first features having a top, sidewalls and a width.