Lithographic resists

Numerous studies have probed how novolac microstructure influences resist lithographic properties. In one example, a series of resists were formulated from novolacs prepared with varying feed ratios ofpara-l/neta-ctesol. These researchers found that the dissolution rate decreased, and the resist contrast increased, as the para-/tneta-cresol feed ratio increased (33). Condensation can only occur at the ortho position ofpara-o.resol, but can occur at both the ortho- and ra-positions of meta-cresol. It is believed that increased steric factors and chain rigidity that accompany increasedpara-ctescA content modify the polymer solubility. 

In summary, substituted silane high polymers are a new class of scientifically interesting radiation sensitive polymers with demonstrated potential as O2-RIE resistant lithographic materials. 

Today, these theories of solutions and of electrolytic solutions are used in the analysis of the solvent development of exposed resists, lithographic mask degradation due to corrosion, electromigration of chromium ions, etc. 

Models for Dissolution Rate. Unlike the senativiiy of typical negative resists, lithographic sensitivity for a positive resist depends on relative dissolution rates of exposed and unexpos areas. A numbin of studies have been reported on tiie effect of molecular weight, M, on rate of dissolution, R. 

The third approach employs modifications of the polymer s physical properties and/or resist processing to minimize contaminant absorption, and is described in the section, "Polymer Properties and Lithographic Performance". 

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