Coating apparatus – With cleaning or reconditioning work support or conveyer
Reexamination Certificate
1998-12-03
2001-05-01
Lamb, Brenda A. (Department: 1734)
Coating apparatus
With cleaning or reconditioning work support or conveyer
C118S429000, C901S041000
Reexamination Certificate
active
06224670
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plating method in which a cup-type plating apparatus is used for plating semiconductor wafers.
2. Earlier Technologies
Cup-type plating methods have been known as a method for conducting bump plating on semiconductor wafers (see Japanese Utility Model Application Laid-open No. 122067/1991 and Japanese Patent Application Laid-open No. 320978/1994). In the cup-type plating methods, a plating process is conducted by the steps including: placing a wafer on a support provided along an upper portion of an opening of a plating tank; supplying plating solution by flowing the solution upward through a bottom of the plating tank; and bringing the plating solution into contact with a surface to be plated of the wafer. The cup-type plating methods can provide identical plating continuously by replacing wafers being placed on the support, thus have been widely used as suitable methods for automation of plating processes and small lot production.
However in the cup-type plating methods, replacement of wafers on each occasion of plating process often causes adhesion of plating solution, after a plated wafer is detached, on the support on which the wafer was placed. On this condition, when another or new wafer is placed, the periphery of the wafer will inevitably come in contact with the plating solution adhered on the support.
Such a phenomenon has been a mal-factor that inhibits satisfactory plating in the cup-type plating methods. Especially, when wafers with seed metal, that is wafers which are preliminarily covered at a surface to be plated thereof with metal such as Cu are plated, the plating solution adhered on the support causes conditions not preferable to a plating process. Specifically speaking, after a wafer with seed metals is replaced with another but before placed on the support to be supplied with plating current, the plating solution adhered on the support will dissolve the seed metal at the periphery of the wafer placed. The wafer with seed metal supplies a surface to be plated with plating current via the seed metal, and if the seed metal on the periphery of the wafer is dissolved, plating current may not be uniformly supplied.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a technology capable of plating satisfactorily even when wafers with a seed metal is plated in sequence by utilizing a cup-type plating apparatus. For solving the problem occurring about a cup-type plating method comprising the step of placing a wafer on a support provided along an upper portion of an opening of a plating tank, for subjecting the wafer to plating, the present invention adopts a cleaning means movable along the support and capable of removing plating solution adhered on the support between an initial and a subsequent plating processes. According to the invention, since the plating solution adhered on the support of the plating tank will have been removed between an initial and a subsequent plating processes, more particularly between that a plated wafer is removed and that next new wafer is placed on the support, even if wafers with seed metal are replaced in sequence on the support, the seed metal on the periphery of a wafer in contact with the support will not dissolve. As a result, plating current can be uniformly supplied, and thereby good or satisfactory plating can be provided. Further, even when the plating solution to be used is very corrosive, the period of time during which the plating solution adheres and corrodes the support will be shortened, so that the support can be prevented from being corroded soon.
In the present invention, the cleaning means for removing the plating solution adhered on the support is preferably formed by either an absorber capable of absorbing plating solution or a suction device capable of sucking plating solution. Such methods of removing the plating solution adhered on the support can include washing with wash water which, however, will be inconvenient because it is assumed that wash water will enter the plating tank to change the concentration of the plating solution. The cleaning means of the present invention can advantageously remove the plating solution adhered on the support without affecting, for instance the concentration of the plating solution, so that the cleaning means will be more suitable when wafers should be sequentially plated. Further, when a cup-type plating apparatus is installed in a clean room, it is especially preferable to use such a cleaning means because it will affect less, for instance the environment in the clean room.
As an absorber being used for the above-described cleaning means, any materials are qualified if they can absorb plating solution. For example, sponge or fabric resistant to corrosion with respect to plating solution is preferable. The suction device can be a sucking section which is connected to a suction pump. With the suction device, the sucking section operated to move in contact with the support can remove adhered plating solution.
For carrying out the above-described cup-type plating method according to the present invention, a cleaning apparatus for cleaning a support provided along an upper portion of an opening of a plating tank should include a first arm of which distal end is positionable at the center of the upper portion of the opening of the plating tank, and a second arm which is mounted at one end thereof to the distal end of the first arm and provided at the other end thereof with a cleaning means, and is pivotal about the distal end of the first arm. The cup-type plating method according to the present invention is directed to removing plating solution adhered on the support between an initial and a subsequent plating processes, namely a period of time after a wafer plated is removed from the support but before a next new wafer is placed on the support. Considering replacement of wafers, the arm and cleaning means must be kept apart from a space above the opening of the plating tank other than when plating solution adhered on the support is being removed. Therefore, the cleaning apparatus for the support on the plating tank according to the present invention is constructed to allow the first arm to pivot to move onto the opening of the plating tank for removing plating solution adhered on the support, and allow the first arm to pivot again to move away from the opening of the plating tank after the support is cleaned. The cleaning apparatus according to the present invention having a simple structure may be mounted directly to a cup-type plating tank, or be mounted separately in the vicinity of the tank.
The present invention is not limited to the above embodiments and its other objects, features, and advantages will be apparent from the following detailed description in conjunction with the relevant drawings. It is also understood that various changes and modifications not departing from the spirit of the prevent invention will be covered by the scope of the present invention.
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patent: 4416577 (1983-11-01), Inatoa et al.
patent: 4635328 (1987-01-01), Palmer
patent: 4693664 (1987-09-01), Schweiker
patent: 4781519 (1988-11-01), Monforte
patent: 5044063 (1991-09-01), Voellmir
patent: 5098024 (1992-03-01), MacIntyre et al.
patent: 5377913 (1995-01-01), Van Der Woude
Electroplating Engineers of Japan Limited
Lamb Brenda A.
Watov Kenneth
Watov & Kipnes P.C.
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