Semiconductor RAMs: Limits to growth

Semiconductor memories are the most competitive, high technology products in the semiconductor industry. Typically, each type of semiconductor RAM introduced to the market quadruples in the number of bits per chip every two to four years. This increase in bit capacity has been achieved simultaneously with an improvement in performance, as well as a steadily decreasing price per bit. The exponential rate of growth of semiconductor memories over the last eight years can be attributed to the advancement in the following three areas: (1) design innovations leading to simpler and smaller memory cells, improved sense amplifier techniques, and more effective overall circuit design; (2) tighter design rules and smaller element sizes due to improved process technology, and (3) larger chip sizes possible because of higher processing yields.