reaching the semiconducting layer. This is known as surface passivation, a method that became critical to the semiconductor industry as it later made possible the mass-production of silicon integrated circuits. He presented his findings in 1957. Building on his surface passivation method, he developed the metal–oxide–semiconductor (MOS) process. He proposed the MOS process could be used to build the first working silicon FET, which he began working on building with the help of his Korean colleague Dawon Kahng. The metal–oxide–semiconductor field-effect transistor (MOSFET), or MOS transistor, was invented by Mohamed Atalla and Dawon Kahng in 1959. The MOSFET was the first truly compact transistor that could be miniaturized and mass-produced for a wide range of uses. In a self-aligned CMOS process, a transistor is formed wherever the gate layer (polysilicon or metal) crosses a diffusion layer. With its high scalability, and much lower power consumption and higher density than bipolar junction transistors, the MOSFET made it possible to build high-density integrated circuits, allowing the integration of more than 10,000 transistors in a single IC. CMOS (complementary MOS) was invented by Chih-Tang Sah and Frank Wanlass at Fairchild Semiconductor in 1963. The first report of a floating-gate MOSFET was made by Dawon Kahng and Simon Sze in 1967. A double-gate MOSFET was first demonstrated in 1984 by Electrotechnical Laboratory researchers Toshihiro Sekigawa and Yutaka Hayashi. FinFET (fin field-effect transistor), a type of 3D non-planar multi-gate MOSFET, originated from the research of Digh Hisamoto and his team at Hitachi Central Research Laboratory in 1989. Importance Transistors are the key active components in practically all modern electronics. Many thus consider the transistor to be one of the greatest inventions of the 20th century. The invention of the first transistor at Bell Labs was named an IEEE Milestone in 2009. The list of IEEE Milestones also includes the inventions of the junction transistor in 1948 and the MOSFET in 1959. The MOSFET (metal–oxide–semiconductor field-effect transistor), also known as the MOS transistor, is by far the most widely used transistor, used in applications ranging from computers and electronics to communications technology such as smartphones. The MOSFET has been considered to be the most important transistor, possibly the most important invention in electronics, and the birth of modern electronics. The MOS transistor has been the fundamental building block of modern digital electronics since the late 20th century, paving the way for the digital age. The US