Chemical amplification type positive resist compositions are pattern-forming materials which, when irradiated with a radiation such as, e.g., far ultraviolet rays, generate an acid in the exposed areas and come to have a difference in solubility in a developing solution between the areas irradiated with the actinic radiation and the unirradiated areas as a result of a reaction catalyzed by the acid to thereby form a pattern on the substrate.
Surfactants are generally incorporated into such chemical amplification type resist compositions in order to eliminate striations and the like and improve applicability. Examples of the surfactants in general use include nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene/polyoxypropylene block copolymers, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters, and further include fluorochemical surfactants, organosiloxane polymers, and acrylic acid or methacrylic acid (co)polymers. In JP-B-7-21626 is disclosed a resist composition for semiconductor microfabrication which comprises an alkali-soluble resin, an organic solvent containing at least a monohydroxy monocarboxylic acid ester, a fluorochemical surfactant, and a radiation-sensitive substance. Furthermore, JP-A-7-230165 discloses a chemical amplification type photoresist composition employing a combination of a solvent of a specific structure and a fluorochemical surfactant, while JP-A-2000-162768 discloses one employing a fluorochemical surfactant having a specific structure.
With the recent trend toward scale down and higher throughputs, it has become important to diminish errors caused by exposure. However, the resists of the related art described above have a problem concerning defect generation during development and this has resulted in a considerable decrease in yield.