July 2011
Intermediate to advanced
520 pages
13h 29m
English
21
Semiconductor Fabrication
Silicon certainly possessed the exotic requirements for effective semiconducting, but the principal reason for its widespread use in integrated electronic circuits was more mundane: silicon’s own oxide, SiO2, could be formed easily on the silicon itself to provide a stable metal oxide insulator to control electronic function. The SiO2 layer also can shield the silicon layer below from the high-energy ion beams or high-temperature gaseous diffusion implantation of dopants in the fabrication process. That is, the superior insulating property of the SiO2 layer could be used to control the doping of the silicon into specified areas with extraordinary precision, and in the very component-dense environment of integrated circuits, this ability to precisely control the areas of doping is critical. Further, the protection of the silicon semiconductor during the harsh fabrication process was of paramount importance for a high-quality yield. This is why the metal oxide semiconductor field effect transistor (the MOSFET) and its progeny, the complementary metal oxide semiconductor (CMOS), quickly became the flagship transistors in integrated circuits for modern electronic products.
Growing Crystals
To make silicon semiconductors, high-purity crystalline silicon (less than one part per billion impurity) is formed from the extraction of SiO2 from common sand through several chemical reactions to first form polysilicon. Heating the polysilicon to form a melt, and then ...
