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Monique Ercken, Roel Gronheid, Ivan Pollentier & Philippe Leray, IMEC, Leuven, Belgium

ABSTRACT

193nm immersion lithography is rapidly moving towards industrial application. A large number of tools has been installed worldwide and they, of course, will require immersion-capable processing to be available. Resist processes without protective topcoats are the favored solution for introduction into mass production, from a cost-of-ownership perspective. This approach adds at least two extra constraints to the list of resist requirements: low leaching and high dynamic contact angle. Various components in the resist show (before and/or after exposure) at least some solubility in water and therefore are likely to leach into the water. This can be a source for lens contamination and resist defectivity. Next to that, the dynamic ‘receding’ contact angle is considered as one of the key parameters to control the amount of water droplets left behind on the wafer surface after exposure. These factors make the selection of a resist for processing without a topcoat as a barrier layer quite challenging, because now minimized leaching, acceptable contact angle and superior overall litho performance (at half-pitches as small as 45nm) are to be met simultaneously. In this paper, we will address whether current state-of-the-art dedicated immersion resists without topcoat are ready for use in production. An overview will be given on the performance of these materials and for some selected parameters a comparison will be made with a process including a topcoat.