New transistor technologies promise faster silicon chips.
At the heart of all electronic-music devices is a multitude of silicon-based integrated circuits (ICs), commonly called chips. At the heart of each IC are millions of tiny transistors that control the flow of electrons through the chip. The power to manipulate musical data ultimately depends on the number of transistors in each IC and the speed at which they switch on and off.
Several recent announcements by Intel and IBM bode well for the future of silicon chips. In particular, Intel has demonstrated the continuing veracity of Moore's law (postulated by company cofounder Gordon Moore in 1965). Moore's law states that the number of transistors in a single integrated circuit doubles every 18 months, and it has remained more or less true for the past 35 years. (Moore predicted that the trend would continue only through 1975.)
As transistors get smaller, they also get faster, which Intel demonstrated in its latest designs. The new devices are 30 percent smaller and 25 percent faster than today's transistors, and they include structures that measure a mere 20 nanometers (nm; billionths of a meter) across, with a 0.8 nm — thick gate-oxide base (used to build the transistors), which corresponds to only three atomic layers.
The new devices switch at 1.5 terahertz (THz), ten times the speed of the fastest current transistors. As a result of its experiments, Intel expects by 2007 to build microprocessors that contain 1 billion transistors and operate at 20 GHz. By contrast, the Pentium 4 has 42 million transistors and runs at speeds as fast as 1.7 GHz.
IBM has made several recent announcements regarding improvements in silicon transistors. One of the most fundamental developments is a combination of silicon and germanium (SiGe) in a design called a heterojunction bipolar transistor. In that design, which is specifically aimed at data-communications chips rather than generalized microprocessors, electrons move vertically instead of horizontally, as they do in standard transistors. That makes it easier to shorten the path they must travel, by reducing the thickness of the device rather than reducing its width or length. Those transistors have reached speeds of 210 GHz while drawing one milliamp of current, which is 80 percent faster and 50 percent less power-hungry than current designs. The company expects the new transistors to result in communications chips that operate at 100 GHz within two years.
Another IBM breakthrough is called strained silicon, a process in which silicon atoms are stretched, or strained, to align with the atoms of the substrate material, such as SiGe (see Fig. 1). That alignment causes electrons to experience less resistance and thus move as much as 70 percent faster through the transistor, without having to decrease the transistor's size. By 2003 that could lead to chips 35 percent faster than today's models and circumvent Moore's law.
IBM has pioneered additional innovations, such as the use of copper interconnects between transistors within a chip, which provides a better conductor than the more traditional aluminum. (The new Intel transistors also use copper interconnects, which are much more difficult to implement than aluminum.) Silicon-on-insulator (SOI) designs place a thin layer of silicon on an insulator base, which is said to speed performance and reduce power requirements.
Clearly, increases in the speed and power of silicon chips offer big benefits to electronic musicians, who rely on those chips to generate, process, and transmit musical data. The recent announcements from Intel and IBM mean that the electronic tools of the future will offer musicians ever-increasing capabilities with which to realize their artistic visions.