Re: why wafers are circles?
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Subject: Re: why wafers are circles?
Date: 7/16/2002 5:11:20 PM (GMT-7)
IP Address: 18.104.22.168
In Reply to: why wafers are circles? posted by
The first step in semiconductor manufacturing begins with production of a wafer--a thin, round slice of a semiconductor material, usually silicon.
In this process, purified polycrystalline silicon, created from sand, is heated to a molten liquid. A small piece of solid silicon (seed) is placed on the molten liquid, and as the seed is slowly pulled from the melt the liquid cools to form a single crystal ingot. The surface tension between the seed and molten silicon causes a small amount of the liquid to rise with the seed and cool.
The crystal ingot is then ground to a uniform diameter and a diamond saw blade cuts the ingot into thin wafers.
The wafer is processed through a series of machines, where it is ground smooth and chemically polished to a mirror-like luster.
The wafers are then ready to be sent to the wafer fabrication area where they are used as the starting material for manufacturing integrated circuits.
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