Determination Of Quantitative Resist Models From Experiment

A resist dissolution data analysis tool (PARMEX) has been developed for automatically determining quantitative resist models for use with simulators such as SAMPLE and Prolith. In this software tool, models for both optical and electron beam exposure are supported. Dissolution rate is first related to fundamental exposure state descriptions, such as the normalized fraction of photo-active compound (PAC) exposed or the e-beam deposited energy. The use of rate versus exposure state plots cleanly distinguishes phenomena such as surface rate retardation from resist contrast. An optimizing routine is then used to best fit user specified models to the data. The software is capable of analyzing data for optical exposures on both reflecting and matched substrates. The concept of a "current working set" is introduced to facilitate the use of multiple wafer data sets in the analysis. The raw data can be input in the form of reflectivity versus time, thickness versus time or rate versus depth. The capabilities and utility of the software tool are demonstrated through analyses of Perkin-Elmer DRM measurements for optical exposure of Shipley Microposit 1400-31 on reflecting and non-reflecting substrates, and electron-beam exposure of Hitachi RD2000N using the Perkin-Elmer AEBLE-150. The software allows differences in resist performance, such as those due to surface rate retardation or thermal heating at high electron-beam current to be easily distinguished.