As chip speeds increase, the width of the interconnects described in Problem 3.107 must be reduced. A hypothetical limit to this process would be reached if the interconnect was just one copper atom wide. Use the density of copper (8.96 g/cm³) to estimate the diameter of a copper atom. (Optical interconnects are being developed and are likely to replace copper in this application within a few years.)

Data from problem 3.107

As computer processor speeds increase, it is necessary for engineers to increase the number of circuit elements packed into a given area. Individual circuit elements are often connected using very small copper “wires” deposited directly onto the surface of the chip. In some processors, these copper interconnects are about 22 nm wide. How many copper atoms would be in a 1-mm length of such an interconnect, assuming a square cross section? (The density of copper is 8.96 g/cm³.)