Photoresist, types positive resist

Bowden and his coworkers(j).) proposed a new type of positive electron beam resist which consists of an alkali-soluble novolac and polymeric dissolution inhibitor. The positive working mechanism of this new type positive resist( NPR ) is similar to that for the conventional positive photoresist 10). It was also found that poly(2-methylpentene-l sulfone)( PMPS ) is good as a polymeric dissolution inhibitor for NPR(lil). In addition, it was clarified that one of the difficulties with NPR is phase separation in the resist films(10)(n). 

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. 

There are two types of photoresists negative and positive photoresists. The negative resist reacts upon exposure to hght to form an insoluble form of the photoresist. Addition of developer then dissolves the unexposed regions of the resist. A positive resist reacts when irradiated to produce a soluble form of the resist that is then washed away by the developer. 

There are two types of photoresists. A positive-tone resist is degraded by exposure to light, so that the resist... 

NQD-novolak type positive photoresists have been widely used in the field of high resolution optical microlithography for years. An example of the resist composition is shown in Figure 1. Esters of polyhydroxybenzophenone and 1,2-naphthoquinone diazidc-5-sulfonic acid are commonly used as a photoactive compound (PAC). 

Pos twe-Tone Photoresists. The ester, carbonate, and ketal acidolysis reactions which form the basis of most positive tone CA resists are thought to proceed under specific acid catalysis (62). In this mechanism, illustrated in Figure 22 for the hydrolysis of tert-huty acetate (type A l) (63), the first step involves a rapid equihbrium where the proton is transferred between the photogenerated acid and the acid-labile protecting group ... 

Apart from multi-level layer resist systems, conventional positive-tone resists can be classified into two categories one-component and two-component systems. Classical examples of the former systems are polyfmethyl methacrylate), and poly (butene-1-sulfone) (2,3). Typical examples of the latter system are AZ-type photoresists, which are mixtures of cresol-formaldehyde-Novolak resins and a photoactive compound acting as a dissolution inhibitor... 

New positive-type photoresist systems based on enzymatically synthesized phenolic polymers were developed [55]. The polymers from the bisphenol monomers exhibited high photosensitivity, comparable with a conventional cresol novolak. Furthermore, this photoresist showed excellent etching resistance. The oxidative polymerization of bisphenol-A proceeded by fungal peroxidase from Coprinus cinereus (CiP) in aqueous isopropanol [56]. CiP also catalyzed the oxidative... 

---