Albert de leon's fba8a- http://posts.fanbox.com/tsfb4................................................................................................................................................................................................................................................................................................................................................
How Microcircuits are Made? What could be simpler than common sand and what could be more complicated than a microcircuit? At the same time it is silicon that integral circuits are made of, which at present manage all electronic equipment from supercomputers to mobile phones and microwave ovens. In microcircuit producing plants they fuse and purify the sand making uniform silicon ingots of it. Special knifes cut the ingots into plates as thick as a small coin and several inches in diameter. The plates are cleansed and grinded. Every one of them serves to make lots of microcircuits. The purified silicon plate is oxidized - that is processed with oxygen - which takes place in high temperature. In this way a thin layer of silicon dioxide is formed on the surface. The dioxide layer is very stable chemically, has a high resistance and dielectric properties, which secures reliable isolation of the silicon beyond it. To process the silicon it is essential to remove the oxide from the corresponding areas. A layer of photoresist is applied onto the dioxide layer. The photoresist is a light-sensitive material, soluble in some chemical substances after radiation. Thephotomask is a plate, consisting of transparent and non-transparent areas, acting as a stencil. On the next exposure stage the plate with thephotomask on it is subject to radiation. The photoresist, situated under the photomask transparent areas, is exposed to light. As the result the layer, exposed to light, the structure and chemical properties of which have changed due to radiation, and the silicon dioxide layer underneath may be removed. The radiated photoresist and dioxide layer removal is calledetching. The process is essential to make way to the bottom layer. Etching is based on chemically dissolving the areas not protected by the photoresist mask. As the result of etching material on the unprotected areas is totally removed. The final stage in forming microcircuits is epitaxy, diffusion and metallization. Epitaxy is the process of growing the layers of material reproducing the crystalline structure on the bottom layer. Epitaxy allows to produce uniform atom layers on the plate. Diffusion is used to create pn -areas. For the purpose boron is introduced into the silicon as acceptor and phosphorous and arsenic are introduced as donors. The process consists of heating the plate, and introducing high energy ions into it.Metallization is the final stage of the chip production. During this process thin metal aluminum, gold and nickel layers are besieged,forming electric connections between the active areas and the crystalline devices. These lines conducting current and contact areas may be observed on any microcircuit.........................................................................................................
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