Selective Deposition of Passivating Layer During Spacer Etching

A method of self-aligned multiple patterning comprising:

• forming a to-be-patterned layer over a substrate;
• depositing a mandrel material over the to-be-patterned layer;
• patterning the mandrel material to form a mandrel;
• performing an atomic layer deposition (ALD) to conformally deposit a spacer material over the substrate, the spacer material covering a top surface and sidewalls of the mandrel and a portion of to-be-patterned layer;
• in a plasma etch chamber without a remote plasma source, flowing a process gas, the process gas comprising a halogen-containing gas and a hydrocarbon, a flow rate ratio of the halogen-containing gas and the hydrocarbon being between 3:2 and 10:1;
• in the plasma etch chamber, sustaining a plasma generated from the process gas;
• exposing the substrate to the plasma to anisotropically etch the spacer material, wherein a polymeric layer comprising carbon is selectively deposited over the top surface of the mandrel, the polymeric layer protecting the mandrel from etching, a portion of the spacer material remaining on the sidewalls of the mandrel;
• in the plasma etch chamber, removing the mandrel to form free-standing spacers;
• and
• using the free-standing spacers as an etch mask, patterning the to-be-patterned layer to form a feature.

A method of self-aligned multiple patterning, the method comprising:

• performing an extreme ultraviolet (EUV) lithographic process to pattern a photoresist layer formed over a layer stack comprising a mandrel layer, a dielectric layer, and an anti-reflective coating (ARC) layer over a substrate, the substrate further comprising, below the mandrel layer, an underlying layer;
• performing a pattern transfer etch to etch through the dielectric layer and the ARC layer and patterning the mandrel layer, a portion of the underlying layer becoming exposed;
• depositing a spacer material over the patterned mandrel layer and the portion of the underlying layer;
• removing a first portion of the deposited spacer material that covers top surfaces of the patterned mandrel layer;
• depositing a polymeric layer over the top surfaces of the patterned mandrel layer;
• removing a second portion of the deposited spacer material that covers the portion of the underlying layer;
• removing the patterned mandrel layer and the polymeric layer to form free-standing sidewall spacers;
• and
• forming a recess in the underlying layer by etching the underlying layer using the free-standing sidewall spacers as an etch mask.