Editing Semiconductor (section)

=== Preparation of semiconductor materials ===
Almost all of today's electronic technology involves the use of semiconductors, with the most important aspect being the [[integrated circuit]] (IC), which are found in [[desktop computer|desktops]], [[laptop computer|laptops]], scanners, [[cell-phone]]s, and other electronic devices. Semiconductors for ICs are mass-produced. To create an ideal semiconducting material, chemical purity is paramount. Any small imperfection can have a drastic effect on how the semiconducting material behaves due to the scale at which the materials are used.<ref name=Neamen />

A high degree of crystalline perfection is also required, since faults in the crystal structure (such as [[dislocation]]s, [[crystal twinning|twins]], and [[stacking fault]]s) interfere with the semiconducting properties of the material. Crystalline faults are a major cause of defective semiconductor devices. The larger the crystal, the more difficult it is to achieve the necessary perfection. Current mass production processes use crystal [[ingot]]s between {{convert|100|and|300|mm|in|abbr=on}} in diameter, grown as cylinders and sliced into [[wafer (electronics)|wafers]]. The round shape characteristic of these wafers comes from [[Boule (crystal)|single-crystal ingots]] usually produced using the [[Czochralski method]]. Silicon wafers were first introduced in the 1940s.<ref>{{cite journal |author=Reinhard Voelkel | title=Wafer-scale micro-optics fabrication | journal=Advanced Optical Technologies | year=2012 | volume=1 | issue=3 | page=135 | doi=10.1515/aot-2012-0013| bibcode=2012AdOT....1..135V | s2cid=137606531 | doi-access=free }}</ref><ref>{{cite book |author1=T. Doi |author2=I.D. Marinescu |author3=Syuhei Kurokawa | title=Advances in CMP Polishing Technologies, Chapter 6 – Progress of the Semiconductor and Silicon Industries – Growing Semiconductor Markets and Production Areas | pages=297–304 | publisher=Elsevier | year=2012 | doi=10.1016/B978-1-4377-7859-5.00006-5}}</ref>

There is a combination of processes that are used to prepare semiconducting materials for ICs. One process is called [[thermal oxidation]], which forms [[silicon dioxide]] on the surface of the [[silicon]]. This is used as a [[gate dielectric|gate insulator]] and [[LOCOS|field oxide]]. Other processes are called [[photomask]]s and [[photolithography]]. This process is what creates the patterns on the circuit in the integrated circuit. [[Ultraviolet light]] is used along with a [[photoresist]] layer to create a chemical change that generates the patterns for the circuit.<ref name=Neamen />

The etching is the next process that is required. The part of the silicon that was not covered by the [[photoresist]] layer from the previous step can now be etched. The main process typically used today is called [[plasma etching]]. Plasma etching usually involves an [[plasma etching|etch gas]] pumped in a low-pressure chamber to create [[plasma (physics)|plasma]]. A common etch gas is [[chlorofluorocarbon]], or more commonly known [[Freon]]. A high [[radio-frequency]] [[voltage]] between the [[cathode]] and [[anode]] is what creates the plasma in the chamber. The [[wafer (electronics)|silicon wafer]] is located on the cathode, which causes it to be hit by the positively charged ions that are released from the plasma. The result is silicon that is etched [[anisotropy|anisotropically]].<ref name=Feynman /><ref name=Neamen />

The last process is called [[doping (semiconductor)|diffusion]]. This is the process that gives the semiconducting material its desired semiconducting properties. It is also known as [[doping (semiconductor)|doping]]. The process introduces an impure atom to the system, which creates the [[p–n junction]]. To get the impure atoms embedded in the silicon wafer, the wafer is first put in a 1,100 degree Celsius chamber. The atoms are injected in and eventually diffuse with the silicon. After the process is completed and the silicon has reached room temperature, the doping process is done and the semiconducting [[Wafer (electronics)|wafer]] is almost prepared.<ref name=Feynman /><ref name=Neamen />