Patent ID: 7157189
Filing Date: 2007-01-02
Classification: G03F

Abstract:
1. A process for producing photomasks for optical lithography, which comprises the steps of: providing a transparent substrate; applying a layer of a mask material on the transparent substrate; applying a layer of photoresist on the layer of the mask material, the photoresist comprising: heating the layer of the photoresist to remove the solvent resulting in a photoresist film being obtained; writing a structure in the photoresist film using a focused electron beam resulting in an exposed photoresist film having exposed parts, in which a strong acid is liberated from the photo acid generator, and unexposed parts, in which no acid has been liberated; heating the exposed photoresist film so that, in the exposed parts, acid-labile groups on the film-forming polymer are cleaved and polar groups are liberated resulting in a contrasted resist film being obtained; developing the contrasted resist film using a developer resulting in a structured resist having lands and trenches disposed between the lands and in which the mask material is bare; adding an amplification agent to the structured resist, the amplification agent having at least one reactive group which can react with the anchor groups of the film-forming polymer resulting in the amplification agent bonding to the film-forming polymer contained in the lands, so that an amplified resist is obtained; removing any excess amplification agent; and etching away bare mask material resulting in the structure being transferred to the layer of the mask material.