it seals the opening to cause formation of a Bernoulli drawing force for forming the successive radial positions of the disk as each portion is passed over the opening. Such drawing force momentarily deflects each portion of the rotating disk toward the opening, causing a deflected portion of the disk to remain substantially in contact with a magnetic recording or reproducing head movable along the opening and thus ensuring stability of the head-to-disk contact.
In order to exert the drawing force, vacuum pressure is generated around the head. The disk is forced toward the head for establishing firm contact with the later so as to enable a steady transfer of information between the head and the disk. Such arrangement for establishing head-to-disk contact is successful to assure head-to-disk contact. However, the magnitude of vacuum pressure to be generated around the head fluctuates. Namely, fluctuation of the vacuum pressure is caused by tolerance in the surface flatness of a stabilizer block which determines the sealing ability. The sealing ability may be influenced not only by surface flatness of the stabilized block but also by waving of the flexible disk during rotation. Due to such fluctuation of magnitude of vacuum generated around the magnetic head, contacting force between the head and the disk can fluctuate to cause variation in information transfer performance.

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 gener