Resist commercial positive diazoquinone

Although many types of compounds have been tested as sensitizers in phenolic host resins (Novolacs, Resols, etc.) (S), all commercial positive resists employ aromatic diazoquinones of some type which photochemically generate base soluble products via Wolff rearrangement initiated by the loss of nitrogen (6). A staggering variety of diazoketones have been synthesized and evaluated for lithographic purposes, but derivatives of J[ and 2 are most commonly employed (5). 

The diazoquinone-novolac positive plates were only a moderate commercial success, but interest in the diazoqunone-novolac systems was revived in the 1970s when the resolution requirements of the semiconductor industry outpaced the capabilities of the negative bis-azide resists then in use. It was during this time that the diazoquinone resists established themselves as nonswelling, high-resolution imaging materials in the semiconductor industry. 

A positive resist system can be of either two types. The classical diazoquinone system represents a photochemical rearrangement reaction which is the basis of commercial photoresists. Scissloning or degradation of a polymer chain by light or electrons Is a later example of solubility induced change. We will examine this change in detail. 

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