Chemical-based shrink techniques

The postexposure-based techniques are grouped into three broad categories, namely, reflow-based. shrink techniques, chemical-based shrink techniques, and plasma-assisted shrink techniques. The reflow-based shrink techniques comprise thermally induced reflow and electron-beam heating-induced reflow of patterned resist features. The chemical-based shrink techniques comprise those techniques that either increase or decrease the sidewall thickness of already patterned resist features, thus effectively altering their critical dimension. Examples of chemical-based shrink techniques that result in an increase in the sidewall of the patterned features include techniques based on RELACS (resolution enhancement of lithography assisted by chemical shrink) and CARL (chemical amplification of resist lines).Examples of chemical-base shrink techniques that result in decrease... 

The two main approaches employed in chemically induced CD shrink techniques are based on sidewall formation and sidewall erosion, respectively. 

Chemically induced CD shrink techniques based on sidewall formation... 

Chemically induced CD shrink techniques based on sidewall erosion rely on chemical reactions that preferentially take place at the sidewalls of already-patterned resist features, leading to their erosion. The hydrophilic overlayer process is a good example of this technique. 

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