抄録
Recently reported ArF positive photoresists can be classified into three groups: derivative methacrylate copolymers (methacrylate resist), methacrylate copolymers functionalized with pendant alicyclic moieties (alicyclic resist), and cycloolefin-maleic anhydride copolymers (cycloolefin resist). Each system has its own advantages and drawbacks in the viewpoint of lithographic properties.
Methacrylate resists have been used for the assessment of ArF lens performance. However, it is hard to apply them in real device process because of their low plasma-etch resistance. Previous studies have reported that alicyclic resists possess adequate etch resistance with the help of cyclic carbon units, however these resists show poor adhesion and seldom dissolve in 2.38% TMAH developer. The cycloolefin resists will be good candidate for addressing the trade-off between etch resistance and requisite material properties for lithographic performance because these resists, unlike methacrylate-based resists, contain large quantities of alicyclic structures directly in the polymer backbone and such properties as dissolution and adhesion can be readily controlled by incorporation of -COOH and -OH functional groups into cycloolefin structures.
We have synthesized poly(2-hydroxyethyl 5-norbornene-2-carboxylate / t-butyl 5-norbornene-2-carboxylate / 5-norbornene-2-carboxylic acid / maleic anhydride; HNC / BNC / NC / MA) resists with a variety of functional groups and obtained lithographic performance by using ArF stepper(0.6NA). In this paper, we will describe the basic idea for designing of the novel cycloolefin resist and demonstrate lithographic capabilities, especially in terms of process window for 130nm feature. In addition, the etch resistance of this resist will be shown. We believe that off-axis illumination should be applied to 130nm device technology to obtain wider process window
