Tri-Gate

A multigate device or multiple-gate field-effect transistor (MuGFET) refers to a MOSFET (metal–oxide–semiconductor field-effect transistor) that incorporates more than one gate into a single device. The multiple gates may be controlled by a single gate electrode, wherein the multiple gate surfaces act electrically as a single gate, or by independent gate electrodes. A multigate device employing independent gate electrodes is sometimes called a multiple-independent-gate field-effect transistor (MIGFET).

Multigate transistors are one of the several strategies being developed by CMOS semiconductor manufacturers to create ever-smaller microprocessors and memory cells, colloquially referred to as extending Moore's law.

Development efforts into multigate transistors have been reported by AMD, Hitachi, IBM, Infineon Technologies, Intel Corporation, TSMC, Freescale Semiconductor, University of California, Berkeley, and others, and the ITRS predicted correctly that such devices will be the cornerstone of sub-32 nm technologies. The primary roadblock to widespread implementation is manufacturability, as both planar and non-planar designs present significant challenges, especially with respect to lithography and patterning. Other complementary strategies for device scaling include channel strain engineering, silicon-on-insulator-based technologies, and high-k/metal gate materials.

...
Wikipedia