Analysis of the electrical characteristics and structure of Cu-Filled TSV with thermal shock test

The electrical characteristics and failure of a Through-Silicon Via (TSV) were investigated using a thermal shock test. The electrical characteristics, such as resistance (R), self-inductance (Ls), self-capacitance (Cs), and mutual capacitance (Cm), were extracted using a T-equivalent circuit. A cross section of the Cu-filled via was observed by field emission-scanning electron microscopy and the electrical characteristics were measured using a commercial Agilent E4980A LCR Meter. The experimental results revealed R, Ls, Cs, and Cm values of 3.2 mΩ, 29.3 pH, 12 fF, and 0.42 pF, respectively. Cm occurred between the charge-holding TSVs, which changed from 0.42 pF to 0.26 pF due to a permittivity transition of the Cu ion drift. After 1,000 cycles of a thermal shock test, cracks were observed between the opening and around the side of the TSV and Si wafer due to mismatch of the coefficient of thermal expansion between the Cu-plug and Si substrate.