Resists positive/negative

A positive photoresist is one that becomes more soluble in the developing fluid as a result of exposure to light, and so dissolves away leaving the desired pattern in the form of undissolved resist a negative resist becomes less soluble on irradiation, so that it is then the illuminated areas that remain. 

Targeting vector A vector containing a positive selection marker (e.g., neomycin-resistance gene), negative selection marker (thymidine kinase gene) and a multiple cloning site. 

Chart 3.1. Tertiary butyl ester polymers useful in designing positive-negative resists incorporating chemical amplification. 

Figure 3.35. Negative plasma-development process via selective silylation of a positive-negative resist.

Another example is thermally depolymerizable polycarbonates that are sensitized with onium salt cationic photoinitiators (139). As discussed previously (Section 3.2.3), one of the positive-negative resists based on polystyrene with pendant tertiary butyl carbonate protecting groups undergoes acid-catalyzed thermolysis to generate poly( p-vinylphenol), carbon dioxide, and isobutene. Therefore, if the tertiary butyl carbonate moiety is incorporated in the polymer backbone as a repeating unit, such polymers will... 

Polymer Synthesis Fiber treatment Negative resists Positive resists... 

New Stable Resists-Combined Positive-Negative Resists... 

There may be some niche application for laser ablation and designed polymers, e.g., for arrays of structures which could be accomplished by novel systems, such as the combined resists. The application of this combined positive-negative resist is still under discussion. 

Positive resists differ from their negative counterparts principally in their response to actinic radiation, despite the fact that the essential composition of the two resist types are similar in many ways each contains sensitizers or appropriate radiation-sensitive compounds, resins, solvents, and additives. Unlike some negative resists, positive resists do not swell in developer. Moreover, the use of aqueous stripping and developing solutions greatly simplifies the equipment selection for positive resists in process equipment tooling hy allowing low-cost readily available plastics to be used as containers. Problems from the use of flammable solvents are minimized with positive resists. ... 

Ito, C.G. Willson, and J.M.J. Frechet, Positive/negative mid UV resists with high thermal stability, Proc. SPIE 771, 24 (1987) H. Ito, M. L.A. Pederson, K.N. Chiong, S. Sonchik, and C. Tsai, Sensitive electron beam resist systems based on acid catalyzed deprotection, Proc. SPIEW86, 11 (1989). 

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