Mohamed Atalla
Mohamed M. Atalla (1924-2009) was an Egyptian-born engineer and physicist at Bell Labs who developed the silicon-silicon dioxide surface passivation method that made reliable silicon devices possible and who, with Dawon Kahng, built the first working MOSFET in 1959. After leaving Bell Labs he worked at Hewlett-Packard and then founded Atalla Corporation, where he became a pioneer of secure banking technology, including personal identification number (PIN) verification and encryption hardware for automatic teller machines. He is thus unusual among transistor-era figures in having made lasting contributions both to semiconductor devices and to computer security.
His central achievement in the laboratory was surface passivation: showing that a thin, thermally grown layer of silicon dioxide could tame the silicon surface. Born in Port Said, Egypt, Atalla studied at Cairo University and then at Purdue University, where he earned his doctorate in 1949, and joined Bell Labs. The problem he faced there in the mid-1950s was that the surface of a silicon wafer was full of electrical states that trapped charge, so that leakage and instability ruined devices and no electric field could reach into the silicon. Atalla found that oxidizing silicon in a furnace produced a layer that bonded to the surface and greatly reduced these surface states. His work on the oxide appeared in a 1959 Bell System Technical Journal paper by him and colleagues, and it provided the basis for the later planar process, as well as for the MOSFET.
The MOSFET followed directly from the oxide work. With a reliable oxide, the idea of a field-effect transistor, in which an electric field from a gate would control a conducting channel in the semiconductor, could finally be tried in silicon. Atalla led the effort and, with Dawon Kahng, built a working metal-oxide-semiconductor field-effect transistor in 1959, announcing it at a device research conference in 1960. Their roles are often described together: Atalla supplied the surface physics and the oxidation methods, while Kahng contributed device design and fabrication. Atalla and Kahng later received the Stuart Ballantine Medal from the Franklin Institute for their work.
After Bell Labs he changed field and built a second career in security. He worked at Hewlett-Packard in the early 1960s on semiconductor devices, and in the early 1970s he founded Atalla Corporation, whose products addressed a growing problem: banks were installing electronic terminals and needed to verify customers without exposing their secrets. He is credited with a system for generating and checking personal identification numbers, and his company built hardware security modules that protected encryption keys in banking networks, commonly known as the Atalla Box. Variants of such devices and the techniques behind them remain central to payment security.
A frequent misunderstanding is that the MOSFET was an immediate commercial triumph or that Atalla alone invented it. The first devices were slow and no match for the mature bipolar transistor of the time, and Bell Labs at first did not push the idea; it was developed by others in the mid-1960s. The invention was a joint effort, and the surface passivation in particular had been developed by a team. Atalla's name is also sometimes confused with the later success of his company, so it is helpful to separate his two careers.
Today his work is everywhere, in a literal sense. Silicon chips are protected by thermal oxide, billions of MOSFET gates are built on that principle, and every time a customer enters a PIN, the practices he helped establish are in use. He died in 2009 at the age of 85.
Read Mohamed Atalla as the engineer who made the silicon surface behave: the oxide he studied unlocked both the MOSFET and the planar chip, and his later security work applied the same careful engineering to protecting money.