Materials, and the science of materials, are what has enabled the semiconductor industry to progress from the first integrated circuits to the most complex systems on chip and processors that are being manufactured today.
While there have been many materials suggested for chips over the past few decades, the predominant ones have been variations of silicon, in large part because the process has been so well tested and proven that it is hard to justify replacing it from a cost and yield perspective. Likewise, interconnects are largely copper.
But there also have been a host of other materials that have been included in semiconductors, ranging from thin films to improve or retard the flow of electrons through channels in the chip, oxides (low k and high k) to improve signal integrity by providing a buffer between tightly packed wires,
As the leading edge of design edges forward, though, there is much consideration being given to different materials at every step of the design and manufacturing process in an effort to minimize current leakage, quantum effects, and the electrical and physical effects from thinner wires, smaller features and more complex signal routing.