Rational design of a high-performance silicone polymer etching solution using a linear alkane swelling solvent for advanced packaging applications

초록

In this study, a high-performance silicone glue etchant with a defined certificate-of-analysis (CoA) parameter and quantitative analysis method is proposed for wafer-supporting system (WSS) debonding process of wafer-level packaging (WLP). In-use etchant (F/NEP), composed of tetrabutylammonium fluoride (TBAF) in N-ethyl-2-pyrrolidone (NEP), suffers from slow etching due to limited fluoride penetration through siloxane network and moisture-induced performance degradation ascribed to the hygroscopicity of TBAF. To overcome these limitations, a linear alkane swelling solvent (LASS)-added etchant was formulated using Hildebrand solubility matching to induce strong swelling of the silicone glue matrix. Among LASS candidates, pentane provided the largest free volume expansion and efficient transport of naked F⁻ ions. When 3.0 wt% TBAF dissolved in N-octyl-2-pyrrolidone (NOP) was combined with 70.0 wt% pentane (PENT70-F/NOP), the etchant achieved an etching rate of 96.5 μm min−1, representing a 12.1-fold improvement over F/NEP (8.0 μm min−1). PENT70-F/NOP also maintained its etching rate up to the critical moisture threshold of 2.0 wt%, in contrast to degradation observed at 0.1 wt% in F/NEP. Furthermore, FT-IR-associated CoA parameter and its upper specification limit were established for reliability. This newly developed PENT70-F/NOP etchant, together with its CoA criteria and analysis method, represents an industry-ready solution package for WSS debonding process. © 2026 The Korean Society of Industrial and Engineering Chemistry.

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