Etch process for reducing directed self assembly pattern defectivity

A method for preparing a patterned directed self-assembly (DSA) layer, comprising:

• providing a substrate having a block copolymer layer on a surface thereof, said block copolymer layer comprising a first phase-separated polymer defining a first pattern in said block copolymer layer and a second phase-separated polymer defining a second pattern in said block copolymer layer;
• performing an etching process to selectively remove said second phase-separated polymer while leaving behind said first pattern of said first phase-separated polymer on said surface of said substrate, said etching process being performed at a substrate temperature less than or equal to about 20 degrees C.;
• and
• during said performing said etching process, monitoring pattern roughness metrics of said first pattern using metrology measurements, and controlling said substrate temperature to maintain said pattern roughness metrics below defined values of pattern defectivity for preventing pattern collapse, wherein said pattern roughness metrics of said first pattern include a mean value of line width roughness, a line edge roughness for a first edge, and a line edge roughness for a second edge, wherein said mean value of said line width roughness is 3.0 nm or less, and said line edge roughness for each of said first and second edges is 3.5 nm or less.

A method for preparing a patterned directed self-assembly (DSA) layer, comprising:

• providing a substrate having a block copolymer layer on a surface thereof, said block copolymer layer comprising a first phase-separated polymer defining a first pattern in said block copolymer layer and a second phase-separated polymer defining a second pattern in said block copolymer layer;
• providing a substrate holder for supporting said substrate, said substrate holder having a first temperature control element for controlling a first temperature at a central region and second temperature control element at an edge region of said substrate;
• setting a target value for said first temperature at or below 20 degrees C. and setting a target value for said second temperature at or below 10 degrees C.;
• and
• performing an etching process to selectively remove said second phase-separated polymer while leaving behind said first pattern of said first phase-separated polymer on said surface of said substrate, said etching process being performed at said target values for said first and second temperatures of said substrate.

A method for preparing a patterned directed self-assembly (DSA) layer, comprising:

• forming a block copolymer layer on a surface of a substrate, said block copolymer layer comprising a first phase-separated polymer defining a first pattern in said block copolymer layer and a second phase-separated polymer defining a second pattern in said block copolymer layer, wherein said forming includes controlling one or more operating parameters selected from cooling rate or heating rate of said substrate, degree of crosslinking, degree of copolymerization, copolymer molecular size, percent of plasticizers in copolymer, annealing temperature, or pressure to result in a glass transition temperature for said first phase-separated polymer in the range of about 50 degrees C. to about 100 degrees C.;
• performing an etching process to selectively remove said second phase-separated polymer while leaving behind said first pattern of said first phase-separated polymer on said surface of said substrate, said etching process being performed at a substrate temperature of 20 degrees C. or less;
• and
• during said performing said etching process, controlling said substrate temperature to maintain a line edge roughness for said first pattern at 3.5 nm or less.