Photoresist developer and method of developing photoresist

A method, comprising:

• forming a resist layer over a substrate;
• patternwise crosslinking the resist layer to form a latent pattern in the resist layer including a crosslinked portion and an uncrosslinked portion of the resist layer;
• and
• developing the latent pattern by applying a developer composition to remove the uncrosslinked portion of the resist layer to form a pattern of the crosslinked portion of the resist layer,
• wherein the developer composition comprises:
• a first solvent having Hansen solubility parameters of 15<δd<25, 10<δp<25, and 6<δh<30;
• an acid having an acid dissociation constant, pKa, of −15<pKa<5, or a base having a pKa of 40>pKa>9.5;
• and
• a second solvent having a dielectric constant greater than 18, and
• wherein the first solvent and second solvent are different solvents.

A photoresist developer composition, comprising:

• a first solvent having Hansen solubility parameters of 15<δd<25, 10<δp<25, and 6<δh<30;
• an acid having an acid dissociation constant, pKa, of −15<pKa<5, or a base having a pKa of 40>pKa>9.5;
• and
• a second solvent having a dielectric constant greater than 18,
• wherein the first solvent and the second solvent are different solvents.