Synergistic Effect of Alkane-Induced Swelling and Fluoride-Ion Attack for Selective Silicone Etching in Semiconductor Process

초록

Wafer-level packaging (WLP) demands complete removal of polydimethylsiloxane (PDMS) glue for reliable interconnects. Here, we present a swelling?assisted PDMS etchant combining tetrabutylammonium fluoride (TBAF), 1?octyl?2?pyrrolidone (NOP), and linear alkanes selected by solubility?parameter matching to PDMS. The optimized formulation of 70 wt% pentane and 30 wt% NOP with TBAF achieves an etch rate of 96.1 μm/min, which is 12-fold higher than a commercial etchant. Short?chain alkanes swell PDMS, increase free volume and accelerate fluoride?ion diffusion and Si?O?Si scission. Wafer?level tests confirm complete PDMS removal without damaging photosensitive polyimide on patterned wafers. Accordingly, the process offers a selective, very high?throughput cleaning route that lowers fluoride burden while preserving material integrity in advanced packaging. - 본 연구성과물은 2025년도 정부(교육부)의 재원으로 한국연구재단의 지원을 받아 수행된 기초연구사업임 (RS-2025-25437296). Keywords: Wafer-level packaging, Solubility parameter, Polydimethylsiloxane, Swelling, Etchant solution