Resist for electron beam lithography and a process for producing photomasks using electron beam lithography

A process for producing a photomask for optical lithography, the process which comprises:

• providing a transparent substrate;
• depositing a first layer of a mask material on the transparent substrate;
• providing a resist including a film-forming polymer obtained by copolymerization of a comonomer mixture, the comonomer mixture including at least one first comonomer having a polymerizable carbon-carbon double bond and an anchor group, the comonomer mixture including at least one further comonomer, the resist including a solvent or a solvent mixture;
• applying a layer of the resist to the first layer and evaporating the solvent in the resist to obtain a second layer of the film-forming polymer contained in the resist;
• producing an image including exposed parts and unexposed parts in the second layer by writing on the second layer using a focused electron beam;
• adding a developer to the second layer to dissolve the exposed parts of the image and to obtain a structured resist in which the unexposed parts of the image form lands and the exposed parts of the image form trenches configured between the lands;
• adding an amplification agent to the structured resist, the amplification agent including a group for coordinating to the anchor group of the polymer;
• obtaining an amplified structure by leaving the amplification agent on the structured resist for a time required to bound the amplification agent to the polymer;
• and
• transferring the amplified structure to the first layer.