Hybrid Bonding of Via-middle TSV Wafer Fabricated using Direct Si/Cu Grinding, Residual Metal Removal, CVD, and CMP

Abstract

Abstract We performed hybrid bonding of a via-middle through-silicon via (TSV) wafer that was fabricated using direct Si/Cu grinding, residual metal removal, chemical vapor deposition of a rear-side insulator, and chemical mechanical polishing. The rear side of the via-middle TSV wafer (wafer diameter: 197 mm, wafer thickness: 22 μm, TSV diameter: 5.5 μm, and total thickness variation: <2 μm), which was mounted on a support glass, was bonded to a Cu electrode wafer (wafer diameter: 200 mm, wafer thickness: 625 μm, and Cu electrode diameter: 6 μm). The bonding was performed at room temperature via a surface-activated bonding using a Si ultrathin film. After hybrid bonding, the support glass was debonded, and vacuum annealing was performed. Cross-sectional observations and electrical measurements of the bonded samples were also performed. Both the SiO2–SiO2 interface and the TSV-Cu electrode interface were bonded by the Si ultrathin film. The measured resistance of the TSV-Cu electrode pair was low (approximately 0.12 Ω), and the leakage current between the TSV-Cu electrode pairs was low (1 pA at 5 V).