Coming soon: Indium Antimonide Valley?

Intel researchers say two elements, indium and antimony, can improve the performance of future transistors

Intel Corp. has improved its work on building a new type of transistor that uses elements other than silicon as building blocks for a future generation of processors, researchers said Wednesday at the International Electron Device Meeting.

Silicon has been the fundamental element used in chip making for years, dating back to the early days of Intel and the region now known as Silicon Valley in California. Over the years, Intel and other chip companies have improved the performance of those chips by scaling, or reducing the size of the transistors every two years or so in order to make them run faster and to fit more transistors on a single chip.

But in order to keep up this pace into the next decade, as parts of transistors approach the size of individual atoms, the chip industry is looking at new ways to build transistors. In some cases, such as Intel's prototype compound semiconductor, new materials are being introduced into the manufacturing process that improve performance without having to rely solely on scaling, said Rob Willoner, a technology analyst with Intel.

In a paper presented Wednesday, Intel researchers explained how two elements, indium and antimony, can improve the performance of future transistors. Intel first announced a prototype indium antimonide transistor earlier this year in partnership with a U.K. firm called QinetiQ Ltd., and it has now reduced the size of the transistor and made it more suitable for mass computing, Willoner said.

Once indifferent high-school science students might vaguely recall the periodic table of elements, which groups elements, based on their properties, into rows and columns. Silicon sits in column IV of the table, which means it has four electrons sitting in its outer-most shell of electrons. Elements look to lose, gain, or share electrons in order to form stable compounds with eight electrons in that outer ring.

Indium sits in the third column of the table, meaning it has three electrons in that outer layer, and antimony sits in the fifth column. When the two elements are combined to build a transistor, that transistor can run about 50 percent faster and use about 10 times less power than a conventional silicon transistor because an indium antimonide transistor has a much higher degree of electron mobility, Willoner said. Mobility is a measure of how freely electrons can move through a transistor.

Intel built the indium antimonide transistor by replacing the channel of a conventional transistor, normally made from silicon, with the compound, Willoner said. Transistors are used to represent the "0s" and "1s" that make up the basic principles of computing; if current is flowing through the channel from one side of a transistor to another, that represents one state, and if the current is blocked by the transistor's gate that represents the opposing state.

The new prototype transistor unveiled Wednesday is an enhancement mode transistor, which means it is normally off until a voltage is applied to the transistor's gate to allow electrons to flow through the channel, Willoner said. The transistor showcased in February was a depletion mode transistor, which means electrons normally flow through the channel unimpeded until the gate is turned off. This is far less power-efficient than enhancement mode transistors, which are the primary transistors used in processors, he said.

Signs announcing Silicon Valley around San Jose, California, will not have to be changed in the future as indium antimonide will not completely replace silicon -- the second-most abundant material on earth -- in future chip making, Willoner said. Intel and QinetiQ's next challenge is to integrate the transistor onto a silicon wafer, since the gallium arsenide wafers used to built the prototype transistor are hugely expensive to produce in large volumes compared to silicon, he said.

The companies hope to have working chips with indium antimonide transistors by the second half of the next decade, Willoner said.

Intel reveals transistors of the future,, Feb. 9, 2005

Copyright © 2005 IDG Communications, Inc.