Chips Go Vertical

Looking for new ways to make ultrafast chips, designers explore the third dimension

11 min read

Vanishingly small transistors have made Moore's Law as much a pop culture phenomenon as a driver for the semiconductor industry. By doubling the number of transistors per microchip every two years, chip makers have given us ever more powerful PCs and electronic gadgets at prices that shrink almost as fast as transistors do. So it may come as a surprise to many that today wires, not transistors, are determining the performance and cost of microchips [see figure, " Delays, Delays"].

Engineers have been figuring out more efficient ways to connect transistors since the first silicon wafer was diced into chips. When he created the integrated circuit at Texas Instruments Inc., in Dallas, over 40 years ago, Jack Kilby had to overcome the so-called tyranny of numbers that engineers of his era labored under as they tried to connect individual transistors the size of pencil erasers to perform useful calculations. The more transistors they tried to use, the more wires they needed and the more power these devices consumed. Scaling up kludged-together devices so they could do useful work would have been next to impossible--too heavy, too expensive, and too hot to handle. TI's Kilby came up with a way to integrate the elements, embedding a transistor, a capacitor, and resistors into a semiconductor material and connecting them with wire bonds to form a working integrated circuit, whereas Fairchild Semiconductor's Jean Hoerni and Robert Noyce developed approaches for planar interconnection of transistors.

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The Transistor of 2047: Expert Predictions

What will the device be like on its 100th anniversary?

4 min read
Six men and a woman smiling.

The luminaries who dared predict the future of the transistor for IEEE Spectrum include: [clockwise from left] Gabriel Loh, Sri Samavedam, Sayeef Salahuddin, Richard Schultz, Suman Datta, Tsu-Jae King Liu, and H.-S. Philip Wong.

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The 100th anniversary of the invention of the transistor will happen in 2047. What will transistors be like then? Will they even be the critical computing element they are today? IEEE Spectrum asked experts from around the world for their predictions.

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