(A) study on effects of non-conductive films(NCFs) material properties and bonding parameters on Cu-pillar/Sn-Ag hybrid bump interconnection using thermo-compression bonding

Abstract

Recently, electronic devices and components have high capacity, high I/O density, high performance, high power efficiency, and miniaturization. In order to satisfy this, ultra-fine pitch bumps are formed on semiconductor chips to use 3D stacking using through silicon via. To use 3D-TSV technique, a method using Non-conductive adhesive films(NCFs), a solid film-type bonding material, has been introduced to supplement for the disadvantages of the existing bonding methods. However, the conventional thermo-compression bonding method using NCFs has the disadvantage that the bonding speed is slow and the productivity is very low by bonding the chips individually. So, research to overcome these disadvantages is being actively conducted. In this study, in order to obtain the optimized solder joint morphology, the factors affecting the NCFs viscosity were studied in terms of bonding parameters and the NCFs material properties. By adjusting phenoxy resin, silica filler and curing agent contents, NCFs with thermo-mechanical properties of CTE $\alpha$1 56.7ppm/$^\circ C$, $\alpha$2 173.1ppm/$^\circ C$, Modulus 3.15Gpa and Tg 172.3$^\circ C$ were obtained. Also, the optimized solder joint morphology in single chip bonding was obtained by developing a 17-second high speed thermo-compression bonding technology with heating rate of about 44$^\circ C$/s. The high speed thermo-compression gang bonding technology was developed about 62 times faster than the existing process method with stable solder joint morphology by double chips gang bonding and triple chips gang bonding through effective temperature and pressure distribution using bonding tool with 40mm x 5mm horn. The electrical properties and reliability test were performed, yielding better daisy chain resistance and reliability than single chip bonding results.