Extreme ultraviolet photoresist and method

A method for lithography patterning, comprising:

• forming a photoresist layer over a substrate, wherein the photoresist layer includes a photoacid generator (PAG), an acid labile group (ALG), and a thermo-base generator (TBG);
• exposing a portion of the photoresist layer to an extreme ultraviolet (EUV) radiation;
• baking the photoresist layer at a first temperature to facilitate a reaction between the ALG and an acid released by the PAG, thereby forming a cleaved ALG, wherein the first temperature is lower than a triggering temperature for the TBG to release a base;
• baking the photoresist layer at a second temperature higher than the triggering temperature, wherein the TBG releases the base, thereby causing a chemical reaction between the cleaved ALG and the base;
• and
• developing the photoresist layer in a developer, thereby forming a patterned photoresist layer.

A method for lithography patterning, comprising:

• forming a photoresist layer over a substrate, wherein the photoresist layer includes a polymer backbone, an acid labile group (ALG) bonded to the polymer backbone, a photo-acid generator (PAG), and a photobase generator (PBG);
• performing a first exposing process to the photoresist layer, wherein the PBG is insensitive to the first exposing process;
• baking the photoresist layer, resulting in a cleaved ALG;
• after the baking of the photoresist layer, performing a second exposing process to the photoresist layer, wherein the PBG is sensitive to the second exposing process and releases a base that reacts with the cleaved ALG;
• and
• developing the photoresist layer in a developer, thereby forming a patterned resist layer.