Nano-mechanical properties of Sn micro-bumps

As ITRS predicted, the diameter of the through silicon via (TSV) would reduce to 1.6 µm by 2015, and the size of TSV interconnection will fall to the range of 10 µm or less, and thus micro-bumps will contain only a few crystal with such a dimension. Because Sn has relatively the high creep resistant and moderate melting point, it is appropriated to be applied in TSV interconnection. This paper investigates the Nano-mechanical properties of Sn micro-bumps containing a single grain. Nano-mechanical test indicates that Sn micro-bumps with the diameter of 40 µm have anisotropic elastic modulus. The surface of Sn micro-bumps with the diameter of 40 µm is without strain-hardening, and the strain hardening index of its section is 0.1701. The decrease of strain hardening index shows that a-axis shear resistance of Sn micro-bumps is far less than that of the c-axis.