Cleaning and liquid contact with solids – Apparatus – Sequential work treating receptacles or stations with means...
Reexamination Certificate
2001-09-24
2003-06-17
Coe, Philip R. (Department: 1746)
Cleaning and liquid contact with solids
Apparatus
Sequential work treating receptacles or stations with means...
C134S902000
Reexamination Certificate
active
06578589
ABSTRACT:
TECHNICAL FIELD
The present invention relates in general to an apparatus for manufacturing a semiconductor wafer, and more particularly to an apparatus for performing a drying processing on a semiconductor wafer substrate in course of transfer, specially on the wafer substrate after the completion of a final cleaning processing.
BACKGROUND ART
In the semiconductor wafer manufacturing process, during the processing prior to a transfer to a heat treatment processing or an epitaxial growth processing of a semiconductor wafer, the wafer is subjected to a final cleaning processing by a wet cleaning such as the RCA cleaning method so as to remove particles, metal impurities, organic materials, natural oxide films, etc., and thereby clean the wafer.
However, a large quantity of cleaning water is used in the final cleaning processing so that water drops are deposited on the wafer surface after the completion of the final cleaning processing. If the wafer is left to stand without removing such deposited moisture, spot-like smears called as water marks are produced on the wafer surface and these smears tend to cause crystal defects in the semiconductor wafer, deterioration in the film quality of an epitaxial film or the like in the following processing step such as a heat treatment or an epitaxial growth processing. Thus, it has been the common practice to dry the wafer to remove the deposited water after the completion of the final cleaning processing of the wafer.
Drying methods well-known for such wafers include, for example, the spin drying method in which after the completion of the final cleaning processing the wafer is rotated at a high speed for a given time in the cleaning chamber to forcibly scatter and remove the water drops deposited on the wafer by the centrifugal force of the rotation and the IPA vapor drying method in which the wafer is dried through the substitution of volatile isopropyl alcohol (IPA) on the moisture deposited on the wafer. Then, after the completion of such drying processing, the wafer is transported by such transfer means as a robot hand to a heat treatment equipment or epitaxial growth equipment which performs the processing of the next processing step.
However, the moisture on the wafer cannot be removed completely even with the cleaning of the conventional semiconductor wafer manufacturing apparatus. Particularly, where a protective oxide film is formed on the wafer surface, there is a problem that the deposited moisture cannot be removed completely by the spin cleaning method due to the wafer surface being hydropholic.
Further, the wafer surface following the completion of the final cleaning processing is in such condition that there is the adsorption of oxygen atoms, oxygen molecules, water molecules, etc., in addition to the water drops. As a result, there is the disadvantage that only with such drying processing as the spin drying method or the IPA vapor drying method used in the conventional semiconductor wafer manufacturing apparatus, it will be possible to remove the water drops from the wafer but the adsorbed oxygen atoms, oxygen molecules, water molecules, etc., cannot be additionally removed completely.
Also, there is another disadvantage that the drying processing is effected within the cleaning chamber where the atmosphere contains much water so that the moisture in the atmosphere as well as the moisture once removed from the wafer are again deposited on the wafer thus making it impossible to remove the moisture completely from the wafer. Thus, in the case of the conventional semiconductor wafer manufacturing apparatus, there is the disadvantage that even if the drying processing is effected after the completion of the final cleaning processing, the moisture, oxygen atoms, oxygen molecules, etc., are still left on the wafer. As a result, there is the disadvantage that such remaining moisture, etc., tend to cause and bring about the occurrence of crystal defects or the deterioration in the film quality of an epitaxial layer in the heat treatment processing or the epitaxiak growth processing of the following processing step.
It is conceivable to perform the drying processing within the cleaning chamber over a long period of time with a view to completely removing the oxygen atoms, oxygen molecules, water molecules, etc., which are adsorbed onto the wafer. In this case, however, the overall time required for semiconductor wafer manufacturing purposes will be increased in correspondence to the drying time.
Further, while it is also conceivable to perform a processing operation of removing the moisture, etc., on the wafer surface in the epitaxial growth furnace, diffusion furnace or the like used in the processing of the following processing step and substituting the atmosphere gas containing them, this substitution of such atmosphere gas also requires much time. Thus, there is the disadvantage that either of these cases causes deterioration of the efficiency of the semiconductor wafer manufacturing process.
Still further, it is conceivable to use a method of newly providing a separate drying chamber in addition to the cleaning chamber so as to prevent the atmosphere in the drying chamber from containing any moisture and thereby to dry the semiconductor wafer. In this case, however, an additional processing step of transferring the wafer from the cleaning chamber to the drying chamber is required and the overall processing time for semiconductor wafer manufacturing purposes is increased in correspondence to such processing, thus failing to overcome the disadvantage that semiconductor wafers cannot be produced efficiently. In addition, there is the disadvantage that the provision of the additional drying chamber makes the apparatus excessively large. Particularly, in recent years, manufacturing apparatus for large-diameter semiconductor wafers of the 400 mm class in diameter, which are now on trial manufacture, tend to become excessively large corresponding to the large diameter and therefore a more compact apparatus is desired.
DISCLOSURE OF INVENTION
In view of the foregoing deficiencies, it is the primary object of the present invention to provide an apparatus for manufacturing a semiconductor wafer, which is capable of removing effectively the moisture, etc., deposited on a semiconductor wafer subjected to a final cleaning processing, so as to produce the semiconductor wafer which is free from the occurrence of crystal defects and high in quality. Also, it is another object of the present invention to provide an apparatus for manufacturing a semiconductor wafer, which is so designed that the manufacturing time of a semiconductor wafer can be reduced to thereby produce the semiconductor wafer efficiently. It is still another object of the present invention to provide an apparatus for manufacturing a semiconductor wafer so designed that the apparatus can be made more compact while ensuring the complete removing of moisture even in the case of large-diameter semiconductor wafers.
In accordance with a preferred aspect of the present invention, there is provided a semiconductor wafer manufacturing apparatus comprising:
a cleaning equipment for performing a final cleaning processing preceding a heat processing on a semiconductor wafer substrate cut from a semiconductor single crystal;
chamber means adapted to receive said wafer substrate after the completion of said final cleaning processing, for the purpose of waiting for or performing said heat processing on said wafer substrate;
a transfer chamber communicating with said cleaning equipment and said chamber means, respectively;
transfer means for transporting said wafer substrate after the completion of said final cleaning processing from said cleaning equipment to said chamber means within said transfer chamber;
heating means for heating said wafer substrate in course of transfer within said transfer chamber to a predetermined temperature; and
gas supply means for injecting an inert gas in the form of a laminar flow onto said wafer substrate in course of transportation within said transfer c
Gima Shintoshi
Imai Masato
Inoue Kazutoshi
Mayusumi Masanori
Nakahara Shinji
Coe Philip R.
Frishauf Holtz Goodman & Chick P.C.
Super Silicon Crystal Research Institute Corp.
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