Semiconductor industry grapples with power crisis
The semiconductor industry is facing a power crisis, but Chenming Hu is confident that the crisis will give rise to innovation.
“It’s a critical time in history, but we always respond to a crisis. There are new opportunities in size reduction, in lithography, and in speed and power,” said Hu, an international leader in microelectronics technology who recently spoke as part of CSL’s Robert T. Chien Distinguished Lecturer series.
As the number of transistors on integrated circuits increase exponentially, the heat generated by the chips is also increasing exponentially and there is greater risk of current leakage. The predicament, Hu said, is that if you try to solve this problem by cutting the power too drastically, then speed is going to be lost. In the past, when researchers cut the power supply voltage, they simultaneously cut the thickness of the oxide layer, which maintained speeds and even increased them.
“Going forward, however, gate oxide thickness cannot be cut anymore, and that’s a problem,” Hu said.
So how do you cut power without losing speed?
Among the many possible solutions outlined by Hu are innovations such as super transistors, universal memory, high electron-mobility materials, or the combination of metal gates with high-k materials, which have a greater ability to hold current. According to Hu, data show that if metal gates are combined with high-k materials, it’s possible to reduce equivalent oxide thickness by a factor of two.
As a result, you can cut power without sacrificing speed.
Hu is the chief technology officer of TSMC in Taiwan -- on leave from the University of California in Berkeley where he is the TSMC Distinguished Professor of Electrical Engineering and Computer Sciences.
Among his many achievements and honors, Hu co-developed FinFET, a vertical transistor structure that has allowed the semiconductor industry to reset the record for the smallest transistor several times over. The FinFET structure is considered a viable way to scale transistor gate lengths down to the incredibly small 10-nanometer level.
In his CSL talk, Hu also said there is no doubt that the scaling process for integrated circuits -- in which transistors shrink and proliferate -- is going to eventually slow down. But according to Hu, history has shown that this slow-down does not necessarily have to lead to an accompanying slow-down in the growth of the semiconductor industry.
“If you look at the historical record between 1965 and 1995, the semiconductor industry introduced a new generation of technology every three years,” he said. “And during that period we had a very good sales growth of 16 percent per year.”
In contrast, from 1995 until today, the semiconductor industry has accelerated to introducing a new generation of technology every two years, but semiconductor industry sales have grown at only 5 percent annually, a much poorer record than during the three-year-per-generation period.
Hu’s hypothesis is that new applications in the market need time to digest the new generation of technology. “So even if we gave the world a new generation of technology every six months, there is not going to be more growth in application technology,” he said.
According to Hu, the industry currently makes about a billion billion transistors each year. “That’s 200 million transistors for each person in the world,” he said. “But another factor of a thousand is certainly in the cards. So if we make a billion trillion transistors, what are we going to do with them?”
One idea, he said, is to use a portion of them to manage power -- just another innovative way to manage the crisis.