Integrated circuits, patterning with photolithography

Photolithography—A method of integrated circuit fabrication that uses a light-sensitive polymer to pattern a silicon wafer with other materials. 

However, EBL write times and tooling costs have decreased sufficiently so that EBL is now routinely used for creating the extremely fine patterns required by the modern electronics industry for integrated circuits. EBL is now often used in combination with photolithography to write-in very fine features such as the gate in a field effect transistor (FET) device. 

There are essentially two approaches to enter the microworld , namely the top-down approach used by engineers and the bottom-up approach borrowed from nature. The top-down approach is based on lithography and related patterning techniques. Microstructures with function are fabricated by lithography, with a rapid trend towards smaller and smaller structures. The closest distance between adjacent electronic components within an integrated circuit (IC) defines the clock cycles and determines the speed of a processor. The current generation of chips is based on 180 nm structures which are produced by photolithography. There is a trend known as Moore s law which states that the scale of an IC halves every 18 month (96). Meanwhile, structures... 

Today the technique of photolithography is a central element in microfabrication, most notably of microchips for the integrated circuits that control computers, mobile phones, and so many other accoutrements of modern life. The principle is simple enough. A mask with a pattern of holes is the template. It is placed over a silicon wafer coated with a photoresist , or resist for short, in the form of a reactive polymer. The resist is rendered insoluble in a chemical solution only after a reaction provoked by ultraviolet light. Irradiation through the mask then prints a latent image, as in photography, on the wafer surface. The wafer is treated with the solvent (the developer ). 

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