Developments in integrated circuits and storage devices used in computers have proceeded at an exponential rate: at present it takes 2–3 years for each successive halving of the component size. Information storage has followed a similar trend in miniaturization of the size of the bits of magnetized material used in hard disks. However, these technologies have fundamental limits, below which the devices no longer function in a predictable manner. For instance, the oxide layers used in complementary metal oxide semiconductor (CMOS) devices are becoming so thin that they conduct electricity in a quantum-mechanical manner by electron tunneling. In 1998 it was estimated that microelectronics and magnetic storage technologies would reach their ultimate limits within 10–30 years. Projections for very large scale integration (VLSI) predict that a single chip will accommodate 90 million transistors with a feature size of 70 nanometers and a clock speed of 900 MHz by the year 2010. Currently, many critical dimensions in semiconductor devices are in the 100-nm range, with some insulating layers being tens of nanometers thick.