Overview

Although the first metal-gate MOSFET had been developed at Bell Labs in 1960, the FET was considered all but impossible to make by those who tried, because it was so unstable. So it was not until 1963 when two young RCA researchers, Steve Hofstein and Fred Heiman, made the first stable and working devices. By the mid-1960s, RCA had some of the first small, metal-can MOSFETs in production and in its own consumer products. In the early 1970s, DMOS, which had been developed in Japan, became available in the United States. It was to become the foundation for subsequent power MOSFET development for the next three decades.

Then in 1976, Siliconix announced MOSPOWER , the world's first commercially available vertical power MOSFETs with their distinctive V-groove, which was etched into the chip's structure. Up until then, MOSFETs had a lateral structure and were limited to power levels of less than 1 Watt. In comparison, with this new type, current flowed through the device vertically. It was capable of faster switching and at power levels of several amps. Unfortunately, the V-groove design was found to create a high-energy field at its point, which was hard to control, and it created stability problems. This in turn led to a truncated structure (without a sharp tip at the bottom of the V-shape), which improved operation somewhat. Although these devices were difficult and expensive to build, as well as requiring an ultra-clean processing environment, they revolutionized power MOSFET technology from then on. The same...