Use Of Vacuum Chambers In The Semiconductor Industry
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A vacuum chamber is a rigid enclosure from which air and other gases are removed by a vacuum pump. The vacuum, or low pressure zone, is created to allow technicians to conduct tests on substances or devices that are required to function in a vacuum. With the use of vacuum chambers that are made out of aluminum, the user can control the magnetic field that is within the chamber. For vacuum chambers where it is important that magnetic fields do not enter the chamber from external sources, the chamber is constructed of mu-metal.
It is necessary to employ a vacuum chamber in various applications of spectroscopy and thin film deposition, used in semi-conductor manufacturing, to insure that substrates are not contaminated. These ultra high vacuum applications are frequently utilized in semi-conductor manufacturing processes, because even the slightest degree of contamination can be disastrous in this industry. As previously mentioned, vacuum chambers are ideal for testing devices that must operate in the vacuum of outer space. Various vacuum chambers are constructed of aluminum because it is not magnetic, unlike other types of metals, and it absorbs small amounts of moisture and trace gases.
Most vacuum chambers are made with ports that allow for instruments to be installed in the walls of the chamber. For processes that only need low to medium levels of vacuum, rubber o-ring seals are utilized. In higher vacuum applications, the flanges have hardened steel knives welded onto them, which cut into a copper gasket when the flange is bolted on.
A type of vacuum chamber frequently used in the field of spacecraft engineering is a thermal vacuum chamber,, which provides a thermal environment representing what a spacecraft would experience in space. These applications also utilize very advanced vacuum pumps.
When mixing resins and silicone rubbers, vacuum chambers are often utilized. In the manufacture of resins and silicone rubber an vacuum is utilized to insure that air bubbles are removed from the mold. A small vacuum chamber is needed for eliminating air bubbles for materials prior to their setting. The material utilized for molding or casting is created according to its manufacturers instructions. Because the material placed in the vacuum will expand to four times its original volume,the mixing container must be large enough to hold a volume of four times the amount of the original material that is being vacuumed to allow for the expansion. If not, there will insufficient volume to complete the process. The material container is then placed into the vacuum chamber; a vacuum pump is connected and turned on. After the vacuum gets to 982 mbar, the material will start to rise. . When the material falls it will plateau and not rise any more. The material is maintained in the vacuum for 3 more minutes in insure that all air has been removed from it. Once this interval is reached the vacuum pump is shut off and the vacuum chamber release valve is opened to equalize air pressure. At this juncture, the vacuum is discontinued, the chamber is opened, and the material is placed in a mold.
Consequently, vacuum chambers used in semi-conductor manufacturing involve processes that are very complex. Since extremely high levels of purity are needed to avoid semi-conductor device contamination, these semi-conductor substrates are produced in ultra high vacuums. As semi-conductor devices have packed increasingly dense circuitry into smaller and smaller silicon real estate, the need for ever increasing vacuum levels has also risen. Consequently the most advanced vacuum chambers and vacuum pumps are utilized in the semi-conductor industry and in space research. In the manufacture of semi-conductor devices, where particles that are several nanometers in width can contaminate a specimen, ultra high vacuums are employed.
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