Wafer container box

Details Wafer container box Wafer container box

2000-04-19

2002-05-07

Luong, Shian (Department: 3728)

Special receptacle or package

For plate or sheet

Fragile or sensitive

C206S711000, C206S832000, C211S041180

Reexamination Certificate

active

06382419

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a container box of a plurality of various wafer materials such as semiconductor silicon wafers, photomask glass plates, liquid crystal cells, recording media and the like for the purpose of storage, transportation or positioning of the wafer materials in mounting and demounting onto and from a processing machine therefor. More particularly, the invention relates to improvements relative to the material of the wafer container box and the mounting structure of various accessory parts of the wafer container box such as robotic flanges, side rails, manual handles and the like.
As a reflection of the very strong requirement for cost reduction of semiconductor devices, semiconductor silicon wafers as a typical class of wafer materials in the electronic industries are now under a continued trend for a rapid shift toward a larger and larger diameter of the wafers reaching or exceeding a diameter of 300 to 400 mm or even larger.
On the other hand, the patterning works to form a circuit pattern on the wafer is under a trend toward higher and higher fineness in order to increase the degree of integration of the semiconductor devices so much. A great increase in the fineness of circuit patterning on a semiconductor wafer cannot be accomplished naturally without upgrading of the cleanness of not only the processing lines and rooms for semiconductor processing but also the wafer container boxes for storage and transportation of the wafer materials before or under processing in an intermediate stage.
As a measure to comply with this requirement for the highest cleanness of the processing environment, a method is proposed in which certain key zones within the processing lines of semiconductor wafers only are kept under the highest cleanness in consideration of the high costs for keeping the highest cleanness over the whole processing lines and the wafer materials under processing are transferred between the key zones as contained in a hermetically sealable wafer container box in order to avoid contamination in the course of transportation. This method can of course be successful only with development of a wafer container box which is suitable for automatic transportation between processing zones and automatic exact loading/unloading of the wafer materials on and from the processing machine without least risks of contamination.
Though not shown by way of illustration, a wafer container box for storage and transportation of wafer materials as well as for loading/unloading of the wafer materials on and from a processing machine in the course of processing has a general structure consisting of a laterally opening body of the container box for holding a plurality of wafer materials in parallel alignment to avoid contacting of adjacent wafers and a covering which hermetically seals the lateral opening of the box body with intervention of an elastic gasket. The opening of the box body is engageable with a processing machine when the container box is set on the machine.
A pair of holding members, which serves to hold a plurality of wafer materials each in a horizontal disposition, are provided on the inside surfaces of oppositely facing side walls. A bottom plate, which may be a raised part equivalent to a bottom plate, is mounted on the bottom of the container box and the bottom plate is provided with a plurality of grooves each having an inversely V-formed cross section, referred to as V-grooves hereinafter, to serve for positioned mounting of the container box on a processing machine and penetrating holes for fixing the container box on a processing machine, referred to as retaining fixtures hereinafter.
A pair of bottom rails run on the bottom surface of the container box along the oppositely facing marginal lines of the bottom surface in the direction from the lateral opening to the rear wall opposite to the lateral opening. Each of the bottom rails is integrally shaped with the box body and the bottom plate. An elastic gasket is interposed between the lateral opening of the box body and the covering to ensure air-tight sealing when the covering is mounted on the opening of the box body. A latch mechanism, which can be operated from outside of the box, is built in the covering and the engagement hook of the latch mechanism is engaged with the lateral opening of the box body to ensure air-tightly sealed condition of the box.
The above mentioned holding members and the bottom plate are shaped separately from the body of the container box and they are fixed to the box body with intervention of an O-ring by means of a metal bolt or an engagement hook. When the wafer container box has to be cleaned by washing, accordingly, a number of these demountable parts are removed prior to washing and, after washing and drying of the box body, they are re-assembled to build up the container box. If washing of the container box is carried out without removing these demountable parts, the cleaning solution is unavoidably retained even by rinse within the narrow interstices between the demountable parts and the box body so that a quite long time is taken for complete drying of the washed box body.
Though not shown by drawings, wafer processing machines in general are equipped with a load port for mounting a wafer container box while a plurality of positioning pins having a semispherical end point and a means for fixing the wafer container box are provided on the upper surface of the load port. Accordingly, the wafer container box is positioned in place on the processing machine by a plurality of V-grooves and fixed to the position by means of the retaining fixture.
When wafers are to be processed by utilizing the above described assembly of apparatuses, the latch mechanism of the covering is first brought to disengagement so as to free the engagement hook from the engagement hole in the front of the container box enabling demounting of the covering which is in a position to close the front opening of the container box. Once the covering has been removed, the wafer materials mounted on the loading boat are taken out one by one from the container box and introduced into the processing machine where the wafer materials are processed.
In the current manufacturing process of semiconductor devices, proposals are made for preventing contamination of wafer container boxes by means of automatic transportation of the wafer container boxes in place of conventional manual transportation by the workers. The actual methods for the automatic transportation of wafer container boxes include the OHT (overhead hoist transportation) method in which the wafer container box is held at the robotic flange supported the flat plate
30
can be provided with one or more of fixing holes
33
in the areas excepting the end portions guide rail, AGV (automated guided vehicle) method in which the container box is transported under lifting by utilizing a pair of bottom rails provided on the bottom surface of the container box or a pair of side rails protruded out of the opposite side walls of the container box and PGV (person-guided vehicle) method. Besides, a method called the RGV (rail guided vehicle) method is known in which the mechanism for transportation of the wafer contained in the box is something resembling a monorail way.
In addition, an improvement of the manual transportation method by workers is proposed according to which manual handling of the wafer container box is facilitated by providing a pair of handles for grasping on both side walls of the container box body.
While the automatic transportation methods of wafer container boxes in the prior art can be classified into several types, it is usually the case that a particular wafer-processing step requires a specific transportation method selected from these types of the methods. Although the method utilizing a pair of bottom rails and robotic flanges is considered to be most versatile in respect of standardization of the process, this method can hardly be universal for all of the wafer processing steps. In practice, d

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