Intel TeraHertz

Lore & Background

The Intel TeraHertz design incorporated two key innovations. One was the depleted substrate transistor, a type of CMOS device built on an ultra-thin layer of silicon atop an embedded insulation layer. This ultra-thin silicon layer is fully depleted to maximize drive current when the transistor is on, allowing faster switching. When off, the thin insulating layer minimizes unwanted current leakage, achieving 100 times less leakage than traditional silicon-on-insulator schemes. Low resistance contacts on top of the silicon layer further enabled the transistor to be very small, very fast, and consume less power.

The other major element was a new gate-dielectric material replacing silicon dioxide. The gate-dielectric separates the transistor's gate from its active region, and the new material—zirconium dioxide—is a superior insulator that reduces current leakages. This allowed the transistor to operate at lower voltages while maintaining higher speed. According to Intel, the new design could use only 0.6 volts.

Reader's Guide

The Intel TeraHertz design represented a significant departure from conventional transistor construction by combining a depleted substrate transistor with a high-k gate dielectric material. The use of zirconium dioxide instead of silicon dioxide addressed the growing problem of current leakage as transistors shrank, enabling lower power consumption and higher operating speeds. The depleted substrate transistor's fully depleted silicon layer and low resistance contacts further enhanced performance by allowing faster switching and reduced leakage. Although Intel unveiled the design in 2001, it was not implemented in commercial processors. The technologies explored in TeraHertz, such as high-k dielectrics and silicon-on-insulator concepts, later influenced subsequent transistor designs in the industry. The design's emphasis on reducing leakage and enabling lower voltage operation anticipated challenges that would become central to later microprocessor development.

Did You Know?

• Intel TeraHertz used zirconium dioxide as a gate-dielectric material instead of silicon dioxide.
• The depleted substrate transistor in TeraHertz had 100 times less leakage than traditional silicon-on-insulator schemes.
• Intel stated the TeraHertz design could operate using only 0.6 volts.
• The TeraHertz transistor was unveiled in 2001 but was not used in processors.