Diazonaphthoquinone (DNQ) is a

diazo In organic chemistry, the diazo group is an organic moiety consisting of two linked nitrogen atoms at the terminal position. Overall charge-neutral organic compounds containing the diazo group bound to a carbon atom are called diazo compounds ...

derivative of naphthoquinone. Upon exposure to light, DNQ converts to a derivative that is susceptible to etching. In this way, DNQ has become an important reagent in photoresist technology in the semiconductor industry. Diazonaphthoquinone sulfonic acid esters are components of common

photoresist A photoresist (also known simply as a resist) is a light-sensitive material used in several processes, such as photolithography and photoengraving, to form a patterned coating on a surface. This process is crucial in the electronics industry. T ...

materials. Such photoresists are used in the manufacture of semiconductors. In this application DNQs are mixed with Novolac resin, a type of

phenol Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire. The molecule consists of a phenyl group () ...

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

. The DNQ functions as a dissolution inhibitor. During the masking/patterning process, portions of the photoresist film are exposed to light while others remain unexposed. In the unexposed regions of the resist film, the DNQ acts as a dissolution inhibitor and the resist remains insoluble in the aqueous base developer. In the exposed regions, the DNQ forms a

ketene In organic chemistry, a ketene is an organic compound of the form , where R and R' are two arbitrary valence (chemistry), monovalent functional group, chemical groups (or two separate Substituent, substitution sites in the same molecule). The na ...

, which, in turn, reacts with ambient water to form a base soluble indene carboxylic acid. The exposed regions of the photoresist film become soluble in aqueous base; thus allowing the formation of a relief image during development.

Chemical reactions

Upon photolysis, DNQ undergoes a Wolff rearrangement to form a ketene. The ketene adds water to form indene-carboxylic acid.

References

{{reflist Diazo compounds