Rock's law or Moore's second law, named for Arthur Rock or Gordon Moore, says that the cost of a semiconductor chip fabrication plant doubles every four years.
The latter is a direct consequence of the ongoing growth of the capital-intensive semiconductor industry— innovative and popular products mean more profits, meaning more capital available to invest in ever higher levels of large-scale integration, which in turn leads to the creation of even more innovative products.
[citation needed] The semiconductor industry has always been extremely capital-intensive, with ever-dropping manufacturing unit costs.
Thus, the ultimate limits to growth of the industry will constrain the maximum amount of capital that can be invested in new products; at some point, Rock's Law will collide with Moore's Law.
[3][4][5] It has been suggested that fabrication plant costs have not increased as quickly as predicted by Rock's law – indeed plateauing in the late 1990s[6] – and also that the fabrication plant cost per transistor (which has shown a pronounced downward trend[6]) may be more relevant as a constraint on Moore's Law.