Method of forming a positive photoresist pattern utilizing contrast enhancement overlayer containing trifluoromethanesulfonic, methanesulfonic or trifluoromethaneacetic aromatic diazonium salt

A method of forming a pattern in contrast enhancement lithography comprising the steps of:

• coating a positive-type photoresist on a substrate to form a positive-type photoresist film;
• forming a photosensitive film, which has a different composition than said photoresist film, over said photoresist film, said photosensitive film consisting essentially of an admixture of a water-soluble organic polymer compound and an aromatic diazonium salt represented by the formula ArN.sub.2.sup.+ X.sup.-, where X.sup.- represents an ion selected from the group consisting of CF.sub.3 SO.sub.3.sup.-, CH.sub.3 SO.sub.3.sup.-, CF.sub.3 CO.sub.2 .sup.- and Ar represents a substituent ##STR10## where R.sub.1, R.sub.2, R.sub.3 may be identical or different, each representing a hydrogen atom, a halogen atom, an alkyl group of 1-6 carbon atoms, an alkoxy group of 1-6 carbon atoms, or a substituent denoted by ##STR11## where R.sub.4 and R.sub.5 may be identical or different, each representing a hydrogen atom, an alkyl group of 1-6 carbon atoms, a hydroxyalkyl group of 1-3 carbon atoms, or wherein R.sub.4 and R.sub.5 may form a 3-7 membered ring through carbon atom, oxygen atom or nitrogen atom together with nitrogen atom to which R.sub.4 and R.sub.5 are linked, or a substituent denoted by ##STR12## where R.sub.6 represents an alkyl group of 1-6 carbon atoms or an alkoxy group of 1-6 carbon atoms, mixing ratio of said aromatic diazonium salt to said water-soluble organic polymer compound being 0.5-4:1 by weight,
• wherein said photosensitive film has bleaching property with radiation on said photoresist film to form a stacked film;
• irradiating the stacked film with radiation of desired pattern;
• removing said photosensitive film with a solvent prior to development of said photoresist film or with a developing solution during said development;
• and
• developing said photoresist film with the developing solution to form a pattern of said photoresist film by removing the irradiated portion of said photoresist film.