Cleaning and liquid contact with solids – Processes – With work or work parts movable during treatment
Reexamination Certificate
1999-03-19
2001-08-07
Markoff, Alexander (Department: 1746)
Cleaning and liquid contact with solids
Processes
With work or work parts movable during treatment
C134S025100, C134S025500, C134S135000, C134S902000
Reexamination Certificate
active
06270585
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and a method for handling substrates in a fluid tank in which the substrates can be placed at a distance from one another as sets, whereby a support strip can be placed on the upper edge region of the substrates. With apparatus as they are known, for example, from EP-B-0 385 536, U.S. Pat. No. 5,265,184, or DE-A-44 13 077 that originates with the applicant of this application, the substrates are held by a substrate-receiving apparatus in the fluid tank or in a substrate holder either by means of a 3-point support or with a 1-point support and additional guide slots on the inner sides of the tank wall or slots in the walls of a hood. In the case of the 3-point support, the support of the substrates is limited to a narrow edge region on the underside of the substrates. Especially with the processing of large wafer dimensions or diameters, for example of 300 mm, such a support is, however, not reliable, since it is not possible to rule out that at least in the upper region, which is remote from the support, the wafers rest against one another, so that the rate of rejection is great. The contacting of adjacent substrates is particularly enhanced during removal of the wafers from the fluid due to the capillary action between the wafers. The use of guide slots and side holders in the fluid tank, or in a hood that is disposed above the fluid tank, has the drawback that the manufacturing costs for the tank and/or the hood are considerably greater. Furthermore, such slots adversely affect a flow of the treatment fluid in the tank that is as uniform and free of disruption as possible. Guide slots furthermore make it more difficult to clean and dry the tank and hood. However, even with the use of guide slots in the drying hood, especially for substrates having large dimensions, the introduction of the substrates into the slots is not ensured, especially due to the capillary action between the substrates that are raised out of the treatment fluid, so that as a consequence damage to the substrates can occur.
A further drawback of the known arrangements is that when the fluid flows rapidly into the tank below the substrates, there exists the danger that the substrates will be raised or will float. Thus, the reliable, parallel and spaced support of the substrates in the substrate-receiving apparatus, or in a substrate carrier, is not guaranteed.
U.S. Pat. No. 5,488,964 A1 discloses an apparatus of the aforementioned type where during the treatment in the fluid tank a rod or a plate is placed upon flat regions of the substrates in order to prevent the substrates from floating up. This rod or plate is first pivoted over the substrates via a drive mechanism when they are introduced into the fluid tank. Prior to removal of the substrates from the fluid tank, the rod or plate is again pivoted away in order to be able to remove the substrates from the fluid tank. Such an arrangement is very expensive and complicated, and more space is required over the fluid tank, especially with respect to the pivoting action. Furthermore, during the loading and unloading process, the substrates are not held by this rod or plate, so that the danger exists that the substrates can rest against and contact one another. It is an object of the present invention to provide an apparatus and method of the aforementioned type with which even substrates having large dimensions can be reliably supported during the processing and/or during the introduction and removal into or from the fluid tank.
SUMMARY OF THE INVENTION
The stated object is inventively realized in that the support strip rests upon or remains resting upon the substrates during the introduction and/or removal process, i.e. during the loading and/or unloading process. In this way, support is also provided in the upper region for the substrates, so that the danger of contact of the substrates or wafers during processing in the fluid tank or during introduction and removal is avoided, and in particular especially also for wafers having large dimensions. Furthermore, also during rapid fluid introduction from below, or where strong introduction nozzles are used, it is not possible for the substrates to be raised or to float up. Due to the presence of the support strip, guide slots are no longer required in or on the tank wall and/or in or on the hood wall, so that the manufacturing costs of the inventive apparatus are less, a disadvantageous effect upon the fluid flow is avoided, and cleaning of the tank is simplified.
Pursuant to a very advantageous specific embodiment of the invention, the support strip can preferably be displaced vertically in a guide means that is provided in the fluid tank and/or a tank hood. In this connection, the guide means can, for example, be a rail that is vertically disposed on a tank wall and/or on a hood wall. Gliding in or on this rail is a support slide that is connected by an angular element with the horizontally disposed support strip.
The support strip preferably rests upon the substrate edges by virtue of its own weight. For this purpose, pursuant to a further specific embodiment of the invention, the weight and/or the material of the support strip is selected in conformity with the desired bearing weight of the support strip upon the substrates. When a guide rail is used for the vertical displacement of the support strip, the support strip, preferably together with the substrate set, can be lowered or raised without it being necessary to provide a drive mechanism just for the support strip.
For specialized applications, however, it can also be advantageous to move the support strip independently from the raising or lowering of the substrates. For this case, the support strip is connected by appropriate connecting elements with a drive mechanism, for example a stepping motor or a driver that is connected with the drive mechanism of the substrate-receiving apparatus, or the like.
The support strip preferably extends over the entire width of the substrate set, so that it supports all of the substrates of the set.
Pursuant to one advantageous specific embodiment of the invention, the support strip, on that side that faces the substrates, is provided with recessed portions, for example notch like slots or slots that narrow in the manner of a V-shape, in which the substrates rest. The recessed portions ensure a reliable retention of the substrates and prevent an alteration of their position relative to one another. Also when great capillary forces occur between the substrates, these substrates remain upright in the set and parallel one after the other, and are reliably spaced from one another. This avoids contact between the substrates, on which also the drying process is possible only with great difficulty and particle danger exists.
Pursuant to a further specific embodiment of the invention, the distances between the recessed portions are selected in conformity with the provided spacing between the substrates, so that in conformity with the spacing selection of the recessed portions of the support strip, the spacing of the substrates relative to one another in the substrate set is fixed. If receiving slots having a defined spacing relative to one another are also found in the substrate-receiving apparatus of the tank and/or in the substrate holder, for instance a substrate carrier, then the spacing of the recessed portions of the support strip are preferably selected in conformity with the spacings of the slots. With regard to the configuration of the receiving apparatus and/or slots for receiving the substrates in fluid tanks or in the substrate carrier, reference is made in particular to the not prepublished DE-A-1 95 46 990, DE-A-1 96 15 108, as well as DE-A-44 28 169 of the same applicant, the content of which to this extent is incorporated in the present application.
For a reliable, defined support of the substrates, be they disk-shaped or rectangular substrates, three points are required. By using a support strip, preferably at the highest point of t
Markoff Alexander
Robert W. Becker & Associates
Steag MicroTech GmbH
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