Other Notable Developments in Transistor Technology

Since the invention of the point-contact transistor in 1947, the number and variety of semiconductor devices have witnessed a tremendous increase as advanced 

The year 1960 saw the invention of the planar process by Hoerni. This process involves the formation of an oxide layer over a semiconductor surface. And with the aid of lithography, windows are defined on the oxide surface, from which portions of the oxide layer is subsequently removed. Impurity atoms are diffused only through the exposed semiconductor surface, and p-n junctions are formed in the oxide window areas. 

An extremely small MOSFET with a channel length of 15 nm was demonstrated by Yu and co-workers at Advanced Micro Devices, Inc. (AMD) in 2001. This device may serve as the basis for the most advanced IC chips containing well over one trillion devices.  

The dynamic random access memory (DRAM) device, a two-element circuit, was invented by Dennard in 1967. The DRAM cell contains one MOSFET and one charge-storage capacitor. The MOSFET functions as a switch to charge or discharge the capacitor. Although a DRAM is volatile and consumes relatively high power, it is expected that DRAMs will continue to be the semiconductor memory of choice for nonportable electronic systems in the foreseeable future.  

15 nm gate length planar CMOS transistor, IEEE lEDM Tech. Dig. p. 937 (2001). G.S. May and S.M. Sze, Fundamentals of Semiconductor Fabrication, Chapter 1, John Wiley Sons, Hoboken, NJ (2004). 

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