Measuring the effects of sub-0.1-μm filtration on 248-nm photoresist performance

Abstract

Photolithography is a key technology driver enabling next generation processes. As line widths decrease to 0.18 tm and below, the critical size ofparticulate contamination decreases proportionately. The implementation of filtration below O.ljim within existing dispense systems raises concern as the removal rating of the filter approaches the size of large molecular weight components of the photoresist.This study was undertaken in order to determine the effects, if any, of 0.05 im and fmer filtration on photoresist performance. Utilizing 248 nm DUV resist, filters were tested in two latest generation dispense pumps, one nitrogen pressurization, and the other having a stepper motor arid diaphragm. The coated 200 mm wafers were exposed at increasing exposure dose and focus in a DUVscanner to produce 0. 1 8 jtm features.This study concludes that as the filter removal rating 'became fmer, the resist performance in terms of photospeed, process window or thermal stability did not change. This indicates that, using existing dispense systems, photoresists can be filtered as fme as 0.03 jtm without significant polymer shearing or the unintentional removal of important materials from the resist. Based on these data, appropriate protection in terms of particle removal is possible as line widths necessitate the use of fmer filters in resist dispense pumps.

Spin-on bottom antireflective coating defect reduction by proper filter selection and process optimization

“…1,2 Filters can be made out of several materials, such as PTFE, Nylon, and polyethylene with pore sizes ranging from 0.02µm and larger. The questions that manufacturers and users must ask are how do these materials compare to each other in filtering out unwanted particulate matter, how compatible are the filter materials to the chemicals being filtered, and how do the filters effect the coating process.…”