Mechanism investigation of filtration on metal and gel removal from DSAL resist

Abstract

Reduction of impurities such as gels and metals is one of the critical requirements in chemistries used in directed self assembly lithography (DSAL). In this study, we focused on elucidating the forms of the gels and metals in block copolymer (BCP) solution to effectively reduce these impurities. As a result, particles or gels, and ions are suggested as forms of metals. To reduce these multiple forms of metals, multistep filtrations such as repetitive filtration of single filter material and combination of different type of filters are conducted. As a result, more than 99.99% of Li and more than 99.9% of Al are reduced with a combination of Nylon 6,6 10 nm filtration and ion exchange filtration. The order of the filtration steps does not impact the removal efficiency. The results should contribute realizing DSAL in semiconductor device fabrication.

Application of Polyimide Porous Membrane to Photopolymer Filter

“…It is very important to reduce the defects and improve the yield in leading-edge semiconductor manufacturing processes [1][2][3]. For the reduction of defects, removal of the contamination source by filtration is effective, and filter makers are working to improve the filtering performance by decreasing the pore size and imparting adsorption property to the membrane [4,5].…”

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].…”

Neutral Layer Material Filtration for Directed Self Assembly Lithography

“…We have investigated PS-b-PMMA block copolymer (BCP) filtration in terms of its impact on the polymer characteristics and gel/metal reduction [3][4][5][6], because BCPs employed in DSAL are considerably different from conventional chemically amplified resists (CAR). We have found the filtration using Nylon 6,6 filter is the most effective among other membrane materials for reducing gels, which is probably derived from insufficient solubility of substantially large molecular weight of the BCPs.…”