Photoresist polymers, methods of forming patterns and methods of manufacturing semiconductor devices

A method of forming a pattern, comprising:

• forming a photoresist layer on an object layer, the photoresist layer including a polymer synthesized from a repeating unit having one or more leaving groups containing an ester group;
• performing an exposure process on the photoresist layer to form an exposed portion from which the leaving groups containing the ester group are removed, and a non-exposed portion at which the leaving groups containing the ester group remain;
• and
• etching the non-exposed portion of the photoresist layer to form a photoresist pattern.

A method of forming a pattern, comprising:

• forming a photoresist layer on an object layer, the photoresist layer including a polymer synthesized from a repeating unit that includes a first leaving group and a second leaving group, the first leaving group including an ester group;
• performing a selective exposure process on the photoresist layer to induce an elimination reaction such that the first leaving group and the second leaving group are separated from the polymer at an exposed portion of the photoresist layer;
• and
• removing a non-exposed portion of the photoresist layer to form a photoresist pattern.

A method of manufacturing a semiconductor device, comprising:

• forming a plurality of active patterns defined by an isolation layer on a substrate;
• forming a photoresist layer on the active patterns and the isolation layer, the photoresist layer including a polymer synthesized from a repeating unit including a leaving group containing an ester group;
• performing an exposure process on the photoresist layer to form an exposed portion from which the leaving group containing the ester group is removed, and a non-exposed portion at which the leaving group containing the ester group remains;
• etching the non-exposed portion of the photoresist layer to form a photoresist pattern;
• partially etching the isolation layer and the active patterns using the photoresist pattern as an etching mask to form a plurality of trenches;
• and
• forming a gate structure in each of the plurality of trenches.