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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.

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A design of experiment (DOE) was implemented to show the effects of various point of use filters on the coat process. The DOE takes into account the filter media, pore size, and pumping means, such as dispense pressure, time, and spin speed. The coating was executed on a TEL Mark 8 coat track, with an IDI M450 pump, and PALL 16 stack Falcon filters. A KLA 2112 set at 0.69µm pixel size was used to scan the wafers to detect and identify the defects. The process found for DUV42P to maintain a low defect coating irrespective of the filter or pore size is a high start pressure, low end pressure, low dispense time, and high dispense speed. The IDI M450 pump has the capability to compensate for bubble type defects by venting the defects out of the filter before the defects are in the dispense line and the variable dispense rate allows the material in the dispense line to slow down at the end of dispense and not create microbubbles in the dispense line or tip. Also the differential pressure sensor will alarm if the pressure differential across the filter increases over a user-determined setpoint. The pleat design allows more surface area in the same footprint to reduce the differential pressure across the filter and transport defects to the vent tube. The correct low defect coating process will maximize the advantage of reducing filter pore size or changing the filter media.