Gold is commonly used in semiconductor packaging to form interconnections (also known as interconnects) that carry electrical signals between different devices in the package. In addition to being a good electrical conductor, gold interconnects are also effective at protecting the heat-generating devices to which they are attached by conducting thermal energy away from the devices to surrounding, cooler regions. Consider a thin film of gold that has a cross section of 60 nm x 250 nm.

(a) For an applied temperature difference of 20°C, determine the energy conducted along a 1-μm-long, thin-film inter connect Evaluate properties at 300 K.

(b) Plot the lengthwise (in the 1-μm direction) and span wise (in the thinnest direction) thermal conductivities of the gold film as a function of the film thickness, L, for 30 ≤ L ≤ 140 nm.