The attempt by General Microelectronics in 1965 to develop a set of 23 custom integrated circuits for an electronic calculator for Victor Comptometer proved to be too ambitious given the reliability of PMOS circuits at the time and ultimately led to the demise of General Microelectronics. General Microelectronics introduced the first commercial PMOS circuit in 1964, a 20-bit shift register with 120 MOSFETs – at the time an incredible level of integration. The high threshold voltage of early MOSFETs led to a higher minimum power-supply voltage (-24 V to -28 V ).

The switching speed was considerably lower, due to large gate capacitances.Since there is no static gate current for a MOSFET, the power consumption of an integrated circuit based on MOSFETs can be lower.ĭisadvantages relative to bipolar integrated circuits were:.

A MOSFET requires fewer process steps and is therefore simpler and cheaper to manufacture (one diffusion doping step : 87 compared to four for a bipolar process : 50 ).

: 87 The main reason is that the MOSFET is self-insulating and does not require p–n junction isolation from neighboring components on the chip.

Given semiconductor device fabrication processes of similar precision, a MOSFET requires only 10% of the area of a bipolar junction transistor.

It would be more than a decade before contaminants in the manufacturing process (particularly sodium) could be managed well enough to manufacture practical NMOS devices.Ĭompared to the bipolar junction transistor, the only other device available at the time for use in an integrated circuit, the MOSFET offers a number of advantages: They fabricated both PMOS and NMOS devices but only the PMOS devices were working. Mohamed Atalla and Dawon Kahng manufactured the first working MOSFET at Bell Labs in 1959. See also: Depletion-load NMOS logic § History and background

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