Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Including contaminant removal or mitigation
Patent
1997-07-29
1999-09-14
Graybill, David E.
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
Including contaminant removal or mitigation
356437, 29 2501, H01L 2130
Patent
active
059535911
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates in general to transporting method and apparatus system for transporting substrate wafers used for manufacturing such advanced devices as semiconductor integrated circuits, liquid crystal panels and solar battery panels, and relates in particular to a method and apparatus to enable maintaining clean substrate surfaces while they are being transported to be processed.
BACKGROUND ART
Advanced device elements such as integrated circuits, semiconductor lasers, active matrix type liquid crystal display panels and solar battery panels are made by successive fabrication of specific film layers and the like on a highly cleaned surface of substrate materials such as silicon, gallium arsenide and glass.
Extreme precision is required for manufacturing of such device parts, and if the wafer materials to be processed are contaminated with adhesion or adsorption of even microscopic contaminating impurities, it becomes difficult to manufacture high quality products.
Further, such substrate wafers are susceptible to accumulating static charges during the processes of transport and various treatments, resulting in their attracting and holding contaminations from the surrounding atmosphere.
For example, if moisture as impurity is adhering to the surface of the semiconductor wafer, it will cause problems during the subsequent device processing. If there is excess moisture adhering to the surface, and the surrounding atmosphere contains a partial pressure of oxygen, a native oxide film is formed on the surface of the wafer, interfering with subsequent fabrication steps such as a deposition of a desired thin film.
Further, during the process of making thin film transistors (TFT) used in liquid crystal display panels, for example, if moisture is present on an electrically insulating film, such as SiN.sub.x, it interferes with the process of forming a uniform and controlled thickness of amorphous silicon (a-Si) film.
Further, during the process of fabricating gate oxide films, for example, if moisture is present on the surface of an n- or p-region, a SiO.sub.x film is produced at the interface between a SiO.sub.2 film and a Si substrate, and such a MOS transistor would not function as a proper switch. Similarly, in the process of fabricating capacitor electrodes, if moisture is present on the surface of a capacitor, a SiO.sub.x film is produced on its surface, and electrical charge storage capability of the capacitor is damaged, and its ability to function as a memory element is destroyed.
In metallization process, a titanium nitride (TiN) film is deposited before forming a tungsten film to prevent spikes caused by the presence of tungsten silicide, and if moisture is present on the Si substrate, the adherence of the interface between Si substrate and TiN is diminished.
Other contaminating substances other than water can also affect the device performance, for example, if heat treatment is carried out in the presence of organic impurities, such as methane, carbon can react with the surface of the silicon substrate to form a SiC film, and device performance is degraded.
For these reasons, various process chamber used in manufacturing of such integrated semiconductor devices are placed in clean rooms capable of filtering dust particles which are usually comprised of microparticles.
Integrated semiconductor circuits are produced after a series of successive fabrication steps, and therefore, the in-process substrate wafers are subjected to a number of processing steps in various process chamber, and are also subjected to a process of being transported from one processing line to another processing line.
During such transporting steps, the wafers are exposed to the atmosphere in the clean rooms which are usually kept at a temperature between 20-25.degree. C., and a relative humidity of about 50%, and although microparticles are filtered out, many gaseous particles are still present. As a result, some impurities present in the clean room can be adsorbed on the surface of the wafers. For
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Ishihara Yoshio
Ohmi Tadahiro
Toda Masayuki
Graybill David E.
Nippon Sanso Corporation
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