Patent Application
20060000494
1. Field of the Invention
The present invention relates to semiconductor fabrication, and more specifically, to a self-draining edge wheel for use in semiconductor wafer processing systems.
2. Description of the Related Art
Semiconductor wafer fabrication operations are typically performed in a repetitive series of fabrication steps. For example, a series of fabrication steps include implantation, material deposition, photolithography, etching, and planarization. The series repeats until the semiconductor wafer is completely fabricated. However, the repetitive series of fabrication steps can produce residue that can remain on a surface of the semiconductor wafer. Residue includes particulates and other undesirable material that can contaminate the metallization lines and structures of the semiconductor wafer. Exemplary particulates can include, among many others, silica, silicon dust, silicate particulates, slurry residue, and metal flakes.
To remove the residue, current semiconductor wafer processing systems include cleaning systems to clean the semiconductor wafers. Specifically, fluid is applied to the semiconductor wafer to wet any residue. Then, the fluid can be removed. However, any structure supporting the wafer at the edge may accumulate the fluid. The accumulated fluid may cause a body of fluid to form at the edge and the structure. Then, the accumulated fluid may recontaminate the semiconductor wafer by possibly reintroducing the particulates that were cleaned.
Another possible problem may result from the accumulated fluid rewetting a dried semiconductor wafer. Specifically, after the semiconductor wafer has been dried, any accumulated fluid on the structure supporting the semiconductor wafer can reapply fluid to the dried semiconductor wafer. Thus, another operation may be required to completely dry the semiconductor wafer.
In view of the foregoing, what is needed is a system and method for preventing the transfer of accumulated fluid on a wafer support structure to semiconductor wafers during a cleaning operation.
Broadly speaking, the present invention is a system and method for preventing the transfer of accumulated fluid to semiconductor wafers during a cleaning operation. Specifically, fluid can accumulate at a semiconductor wafer edge. The fluid at the semiconductor wafer edge transfers to a structure, such as an edge wheel supporting the semiconductor wafer edge. By configuring the edge wheel to drain the fluid and thereby prevent fluid accumulation, the fluid does not transfer to the semiconductor wafer being cleaned. It can be appreciated that the present invention can be implemented in numerous ways, such as a process, an apparatus, a system, or a device. Several inventive embodiments of the present invention are described below.
In an embodiment of a method for processing a wafer, the method includes supporting a wafer with a plurality of edge wheels positioned peripherally around the wafer. The plurality of edge wheels are capable of rotating so as to rotate the wafer. The method also includes causing a fluid present on a surface of the wafer to move toward the plurality of edge wheels to reach an interface formed between an edge of the wafer and a surface of each of the plurality of edge wheels. Further, the method includes channeling the fluid contacting the plurality of edge wheels away from the interface, such that the channeling of the fluid is configured to prevent formation of a meniscus of the fluid at the interface.
In another embodiment of a method for processing a wafer, the method includes supporting a wafer with a plurality of edge wheels positioned peripherally around the wafer. The plurality of edge wheels are capable of rotating so as to rotate the wafer. The method also includes causing a fluid present on a surface of the wafer to move toward the plurality of edge wheels to reach an interface formed between an edge of the wafer and a surface of each of the plurality of edge wheels. Further, the method includes channeling the fluid contacting the plurality of edge wheels away from the interface, such that the channeling of the fluid is configured to prevent formation of a meniscus of the fluid at the interface. The method also includes suctioning the fluid from each of the plurality of edge wheels, such that the suctioning is configured to keep a bottom surface of each of the plurality of edge wheels substantially dry.
In an embodiment of an edge wheel for processing a wafer, the edge wheel includes a top portion and a bottom portion forming a groove therebetween for receiving an edge of a wafer. The bottom portion is configured to channel fluid away from the groove to prevent formation of a meniscus of fluid between the groove and the edge of the wafer.
An embodiment of a system for processing a wafer includes a plurality of edge wheels for supporting a wafer, such that each of the plurality of edge wheels has a top portion and a bottom portion forming a groove therebetween for receiving an edge of a wafer. The bottom portion is configured to channel fluid away from the groove to prevent formation of a meniscus of fluid between the groove and the edge of the wafer. The system also includes an edge wheel dryer disposed proximate to the plurality of edge wheels, the edge wheel dryer having a plurality of vacuum channels configured to suction fluid away from the bottom portion of each of the plurality of edge wheels.
In an embodiment of a method for processing a wafer, the method includes supporting a wafer with a plurality of edge wheels positioned peripherally around the wafer. The method also includes applying a volume of fluid on a surface of the wafer, such that the volume of fluid is sufficient to cause the fluid to move toward the plurality of edge wheels to reach an interface formed between an edge of the wafer and a surface of each of the plurality of edge wheels. Further, the method includes channeling the fluid contacting the plurality of edge wheels away from the interface, such that the channeling of the fluid is configured to prevent formation of a meniscus of the fluid at the interface.
In an embodiment of a method for processing a wafer, the method includes supporting a wafer with a plurality of edge wheels positioned peripherally around the wafer. The method also includes applying a volume of fluid on a surface of the wafer, such that the volume of fluid is sufficient to cause the fluid to move toward the plurality of edge wheels to reach an interface formed between an edge of the wafer and a surface of each of the plurality of edge wheels. Further, the method includes channeling the fluid contacting the plurality of edge wheels away from the interface, such that the channeling of the fluid is configured to prevent formation of a meniscus of the fluid at the interface. The method also includes suctioning the fluid from each of the plurality of edge wheels, such that the suctioning is configured to keep a bottom surface of each of the plurality of edge wheels substantially dry.
Other aspects of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
Embodiments of the invention may best be understood by reference to the following description, taken in conjunction with the accompanying drawings, in which:
The following descriptions describe embodiments of a system and method for processing a wafer to prevent the transfer of accumulated fluid to wafers during a cleaning operation. Specifically, multiple self-draining edge wheels support the wafer during the cleaning operation. Fluid on a surface of the wafer propagates to an edge of the wafer. Upon reaching the edge of the wafer, the fluid can accumulate. The accumulated fluid can contact the multiple self-draining edge wheels and cause the accumulated fluid to coat a surface of each of the multiple self-draining edge wheels. Thereafter, the fluid coating drains away from the contact point with the edge of the wafer.
The drained fluid can then be suctioned away from the multiple self-draining edge wheels to maintain substantially dry self-draining edge wheels. Otherwise, the drained fluid is removed from the surface of each of the multiple self-draining edge wheels through the self-draining properties of the multiple self-draining edge wheels. It will be obvious, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention.
Further, the embodiments described herein are exemplary. It will be appreciated by those skilled in the art that upon reading the description and studying the drawings, various alterations, additions, permutations and equivalents thereof are possible. It is therefore intended that all such alterations, additions, permutations, and equivalents fall within the true spirit and scope of the disclosed embodiments.
The cleaning system 100 includes a plurality of self-draining edge wheels (edge wheels) 120. As illustrated, the edge wheels 120 support the wafer 110 via an interface. Specifically, the interface is formed between a v-like groove of the edge wheels 120 and the wafer 110. The groove positions the wafer 120 to permit rotation of the wafer 110 and the edge wheel 120. However, other interfaces with different shapes can couple the wafer 110 and the edge wheel 120, as long as the other interfaces form when supporting the wafer 110.
The edge wheels 120 are capable of rotating, thus permitting the rotation of the wafer 110. As the wafer 110 rotates, any fluid on a bottom surface or a top surface of the wafer 110 propagates to an edge of the wafer 110. The edge of the wafer 110 is in contact with each of the edge wheels 120 at the interface. Accordingly, the propagated fluid accumulates on the edge of the wafer 110 and the interface. Specifically, accumulated fluid at a bottom surface 130 and a top surface 135 may form. Each accumulation of fluid may form a meniscus that can contaminate each wafer 110 introduced to the cleaning system 100. However, fluid channeling from the interface prevents formation of the meniscus.
In another embodiment of the present invention, fluid can be applied to the wafer 110 while the wafer is stationary, i.e. not rotating. Here, the volume of fluid applied to the surface of the wafer 110 should be sufficient such that the fluid propagates to the edge of the wafer and the interface. The fluid reaching the interface is channeled away according to the embodiments of the present invention described herein.
Fluid channeling occurs because the edge wheels 120 of the present invention are configured to drain fluid from the interface. For example, in an embodiment of an edge wheel 120 having a bottom portion and a top portion, the bottom portion can be configured to drain fluid away from the interface. In another exemplary embodiment, one or more edge wheel dryers 140 can suction the fluid away from the bottom portion of the edge wheels 120 by using one or more vacuum channels. However, it should be appreciated that the edge wheel dryer 140 may or may not be used to suction fluid from the edge wheel 120. In at least one embodiment of the present invention, the edge wheel 120 is configured to drain fluid without suctioning from an edge wheel dryer 140.
At least one edge wheel 120 is coupled to a robotic arm 125. The robotic arm 125 can move the edge wheel 120 and if necessary, any coupled edge wheel dryer 140 away from the wafer 110. By moving the edge wheel 120, the wafer 110 may be moved from or be placed in contact with the grooves of the edge wheels 120. After positioning the wafer 110 in the grooves, the robotic arm 125 moves the edge wheel 120 back to the wafer 110 to secure the wafer 110. However, the edge wheel 120 can be coupled to any other type of mechanical appendage, such as the robotic arm 125, as long as the mechanical appendage can move the edge wheel 120. Further, it should be appreciated that any method of securing the wafer 110 to the interfaces of the edge wheels 120 is possible, as long as the wafer 110 can be secured while permitting rotation.
The cleaning system of
If an edge wheel dryer 140 is used to suction fluid from the internal chamber 230, then an exemplary edge wheel dryer 140 can include a plurality of vacuum channels. For example, an upper vacuum channel 270 can suction fluid away from the groove. Further, a lower vacuum channel 260 can suction fluid from the internal chamber 230. Specifically, a vacuum port 240 can be inserted into a drain 220 of the edge wheel dryer 120. The drain 220 forms a circular channel in the bottom portion of the edge wheel 120 in which the vacuum port 240 is inserted. The vacuum port 240 is sufficiently fitted to the drain 220 to prevent fluid from escaping the suctioning of the fluid into the lower vacuum channel 260. By preventing the fluid from escaping the suction applied from the lower vacuum channel 260, the bottom surface of the edge wheel 120 is kept substantially dry. It should be appreciated that any number of vacuum channels are possible. For example, the upper vacuum channel 270 may be excluded from the edge wheel dryer 140. It should further be appreciated that if there is more than one vacuum channel in an edge wheel dryer 140, any combination of functioning vacuum channels can be employed. For example, the lower vacuum channel 260 can suction fluid while the upper vacuum channel 270 remains inoperative.
In addition, there can be any number of edge wheel openings 205 having varying spaces between each edge wheel opening 205. In yet another embodiment, the edge wheel openings 205 can be positioned in multiple rows. For example, there can be two or more rows of each edge wheel openings 205 to permit fluid channeling from the interface formed by the groove and the wafer 110.
In selecting a material for the edge wheel 120, the ability of the material to attract or repel fluid can be considered. The property of a material's ability to attract or repel fluid is the philicity or phobicity of the material, respectively. For example, the fluid, which can include water, deionized water (DIW), a chemistry, a combination of the chemistry and DIW, and a combination of the chemistry and water may be attracted to or repelled from a particular material. It should be appreciated that any suitable fluid and suitable material used in wafer processing systems is possible, as long as the fluid is drained according to the method of the present invention. Thus, when selecting the material, the property of whether the material attracts or repels a particular fluid can be considered during the selection.
The bottom portion 330 of the edge wheel 120 does not have an internal chamber 230, but instead has multiple cut out regions 310. The cut out regions 310 enable fluid to drain towards the bottom surface of the edge wheel 120, thereby preventing the accumulation of fluid at the interface. Specifically,
However, if the edge wheel dryer 140 is positioned proximately adjacent to the edge wheel 120, then the edge wheel dryer 140 can suction fluid from the edge wheel 120. For example, the lower vacuum channel 260 can be positioned to suction fluid from the bottom surface of the edge wheel 120 by positioning the lower vacuum channel 260 to encompass fluid spun off the edge wheel 120. Although illustrated with one lower vacuum channel opening 430, the lower vacuum channel 260 can include another lower vacuum channel opening (not shown). Thus, multiple lower vacuum channel openings can suction fluid from various locations of the bottom surface of the edge wheel 120.
The embodiment illustrated in
In another embodiment of the present invention, the wafer remains stationary, i.e. not rotating. Further, the wheels may remain stationary. Thus, fluid applied to the surface of the stationary wafer propagates to the edge of the wafer because the volume of the applied fluid sufficiently covers the surface area of the wafer. It should be appreciated that in another embodiment, the wheels may rotate to permit movement of the wafer. However, rotation is not required to propagate fluid to the edge of the wafer.
Next, in operation 730, the method includes operations to channel fluid from an interface. Specifically, the fluid propagated to the edge of the wafer does not accumulate to form a body of fluid having a meniscus. To prevent fluid accumulation, the fluid is channeled away from the interface. Fluid channeling occurs through a combination of a structure of a bottom portion of the wheels and the material composition of the wheels. For example, the structure of the bottom portion can include an internal chamber having openings for draining fluid, cut out regions, a plurality of coupled legs, and angled channels. The structure also includes any of the structures of the embodiments previously described. Further, the material composition of the wheels can consider the phobicity, philicity, and hardness of the material.
Thereafter, in operation 740, the method includes positioning an edge wheel proximately adjacent to the wheels to apply suction to remove fluid from the wheels. It should be appreciated that embodiments of the present invention may or may not apply an edge wheel dryer. Further, the edge wheel dryer can be configured according to the previous embodiments previously described. When using the edge wheel dryer, a vacuum positioned near the bottom portion of the wheels can suction fluid channeled from the interface. Thus, the bottom surface of the wheels remains substantially dry.
To those of ordinary skill in the art, the operations described herein, and illustrated by the drawings, are exemplary. Further, the operations can be performed in any order to permit the draining of fluid from the wheels. Thus, the order of the operations is not limited to any particular sequence.
Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications can be practiced within the scope of the appended claims. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.
