Enhanced Cleaning for the Point-of-Use Filter and its Effectiveness on Wafer Defectivity in Immersion ArF Lithography Process

Abstract

Two versions of a specific 2 nm rated filter containing filtration medium and all other components produced from high density polyethylene (HDPE), one subjected to standard cleaning, the other to specialized ultra-cleaning, were evaluated in terms of their cleanliness characteristics, and also defectivity of wafers processed with photoresist filtered through each. With respect to inherent cleanliness, the ultraclean version exhibited a 70% reduction in total metal extractables and 90% reduction in organics extractables compared to the standard clean version. In terms of particulate cleanliness, the ultraclean version achieved stability of effluent particles 30nm and larger in about half the time required by the standard clean version, also exhibiting effluent levels at stability almost 90% lower. In evaluating defectivity of blanket wafers processed with photoresist filtered through either version, initial defect density while using the ultraclean version was about half that observed when the standard clean version was in service, with defectivity also falling more rapidly during subsequent usage of the ultraclean version compared to the standard clean version. Similar behavior was observed for patterned wafers, where the enhanced defect reduction was primarily of bridging defects. The filter evaluation and actual process-oriented results demonstrate the extreme value in using filtration designed possessing the optimal intrinsic characteristics, but with further improvements possible through enhanced cleaning processes.

Filtration study with nylon membrane for metal removal performance improvement

“…At the end of the extraction period, the fluids filling each capsule was analyzed for levels of 22 metals via inductively coupled plasmamass spectrometry (ICP-MS, Agilent 7700s). [6] RESULTS AND DISCUSSIONS…”

Application of Polyimide Porous Membrane to Photopolymer Filter

“…Filters for semiconductors are required to have chemical resistance and cleanliness [6]. We focused on polyimide which has high purity and excellent chemical resistance as a filter membrane for semiconductors.…”

Novel Fabrication of Three-Dimensional Homogeneous Microporous Polyimide Membrane

“…In the semiconductor device manufacturing process, reduction of defects is required to improve performance and yield, and reduce costs. Filtration of photoresist using filter media is effective for reducing defects [1][2][3]. Generally, the material of the filter media for semiconductors is (PE) polyethylene, (PTFE) polytetrafluoroethylene, or nylon, and the manufacturing method of the polymer porous membrane is the phase separation method or the stretching method [4][5][6].…”