As computer chips grow denser, it becomes increasingly difficult to measure the progression of Moore’s Law. Exacerbating this situation is the mutability of the definition of node names, especially as manufacturers prepare to launch 14nm and 16nm chips. Some analysts imply that, irrespective of the next chip generation, the migration from old to new no longer guarantees the kind of price or performance improvements that it once did. The breakdown between performance and node name began around the mid-1990s as chipmakers not only continued to use lithography to pattern circuit components and wires on the chip, but also started etching away the ends of the transistor gate to make the devices shorter and faster. Eventually, “there was no one design rule that people could point to and say, ‘That defines the node name,'” says Intel fellow Mark Bohr. Despite this change in the transistor measurement trend, manufacturers persisted in packing the devices closer and closer together, assigning each successive chip generation a number about 70 percent that of the previous one. Today the node names are no longer consistent with the size of any specific chip dimension. No matter what definition is applied, numbers in node names have steadily declined, as have the distance between transistor gates.
More info here: IEEE Spectrum (10/28/13) Rachel Courtland