Positive photoresist and negative photoresist contrast, since the photochemical reactions in the exposed area, so that the region becomes easy to dissolve the film, so as to be dissolved and removed during development. It is left to the non-exposed areas of the poor solubility of film. To date, the polyamic acid and o-diazonaphthoquinone photosensitizer acid lipids most positive polyimide photoresist is dissolved by the research in an alkaline aqueous composition having hydroxyl. The latter polymer solubility control action. Because DNQ itself is insoluble in alkaline solution, contact protection polyamic acid and alkaline solutions. Once exposed to light, DNF can be decomposed into indene acid compound dissolved. It lye dissolved increases contact with the polymer, prompting the dissolution of the polymer, which is such a positive resist working process. The advantage is the use of an aqueous developer, the developer is no swelling effect on the film. Therefore, the ability to resist high resolution. The most commonly used diazonaphthoquinone sulfonic acid esters have many world DNQ benzophenone, which is a mixture of different compounds with a substitution degree.