Cleaning apparatus

A cleaning apparatus including a holding table for holding a plate-shaped workpiece, a cleaning nozzle for spraying a cleaning fluid to the plate-shaped workpiece, and a table cover for covering a circumference of the holding table. The table cover includes a top plate for covering an upper side of the holding table and a side plate for covering the circumference of the holding table. The table cover is provided with a netlike mesh sheet spaced from a lower surface of the top plate and another netlike mesh sheet spaced from an inner surface of the side plate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a cleaning apparatus for cleaning a surface of a plate-shaped workpiece such as a semiconductor wafer.

2. Description of the Related Art

Conventionally known is a spinner type cleaning apparatus including a rotatable holding table for holding a wafer and a cleaning nozzle for spraying a cleaning fluid to the wafer held on the holding table being rotated (see Japanese Patent Laid-Open No. 2009-094247, for example). In the cleaning apparatus described in Japanese Patent Laid-Open No. 2009-094247, the cleaning nozzle is pivotally oscillated above the holding table in spraying the cleaning fluid from the cleaning nozzle to the wafer, thereby cleaning off soil sticking to the whole surface of the wafer. Since the cleaning fluid is sprayed to the wafer being rotated, the cleaning fluid on the wafer is scattered by a centrifugal force. To cope with this scattering of the cleaning fluid, a scatter prevention cover is vertically movably provided so as to surround the holding table, wherein the scatter prevention cover is raised in an operative condition of the cleaning apparatus to thereby prevent the scattering of the cleaning fluid.

SUMMARY OF THE INVENTION

A sponge is provided on an inner surface of the scatter prevention cover in the cleaning apparatus to absorb the cleaning fluid scattering from the holding table. Since the sponge has a three-dimensional network structure, the cleaning fluid can be easily absorbed by the sponge. However, the cleaning fluid absorbed by the sponge is hard to discharge. Accordingly, a rate of discharge of the cleaning fluid absorbed by the sponge is low, and when the sponge is saturated with the cleaning fluid, there arises a problem such that the cleaning fluid striking the sponge may become a mist, which may stick to a periphery of the wafer or the holding table.

It is therefore an object of the present invention to provide a cleaning apparatus which can effectively prevent the production of a mist with a simple configuration.

In accordance with an aspect of the present invention, there is provided a cleaning apparatus including a holding table for holding a plate-shaped workpiece; a motor for rotating the holding table; a cleaning nozzle for spraying a cleaning fluid to the plate-shaped workpiece held on the holding table; and a cover for absorbing the cleaning fluid sprayed from the cleaning nozzle and scattered from the holding table holding the plate-shaped workpiece and rotating at a predetermined speed. The cover includes a top plate having an opening for exposing an upper surface of the holding table and a side plate connected to the top plate so as to extend downward therefrom. The top plate is positioned above an upper surface of the plate-shaped workpiece held on the holding table. The side plate is provided with a netlike mesh sheet spaced from an inner surface of the side plate.

With this configuration, the cleaning fluid scattering from the holding table during cleaning does not collide with the side plate of the cover, but it is absorbed by the mesh sheet spaced from the inner surface of the side plate of the cover. Accordingly, there is no possibility that a mist may be produced by a collision of the cleaning fluid with the side plate. Further, when the cleaning fluid is absorbed by the mesh sheet, the cleaning fluid retained in the mesh sheet is allowed to flow downward along the mesh sheet. Since the cleaning fluid absorbed by the mesh sheet is allowed to continuously fall downward along the mesh sheet, the mesh sheet is not saturated with the cleaning fluid, but it can be always maintained in a cleaning fluid absorbable condition. Accordingly, there is no possibility that the cleaning fluid colliding the mesh sheet may become a mist.

According to the present invention, the production of a mist can be effectively prevented by the simple configuration that the mesh sheet is provided inside the side plate of the cover.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will now be described in detail with reference to the attached drawings.FIG. 1is a schematic top plan view of a cleaning apparatus1according to this preferred embodiment.FIG. 2is a schematic sectional view of the cleaning apparatus1as taken along a line A-A inFIG. 1. A configuration of the cleaning apparatus1shown inFIG. 1is merely illustrative and it may be suitably modified. InFIG. 1, a cleaning nozzle is not shown for convenience of illustration.

As shown inFIGS. 1 and 2, the cleaning apparatus1includes a holding table2for holding a plate-shaped workpiece W, a motor6for rotating the holding table2, and a cleaning nozzle5for spraying a cleaning fluid to the plate-shaped workpiece W held on the holding table2during rotation of the holding table2. The cleaning apparatus1is used for cleaning of the plate-shaped workpiece W after performing various kinds of processing such as grinding, polishing, edge trimming, and partial grinding except a peripheral portion of the workpiece W. The plate-shaped workpiece W may be a semiconductor wafer of silicon, gallium arsenide, etc. or may be an inorganic material substrate of ceramic, glass, sapphire (Al2O3), etc.

The cleaning apparatus1further includes a case3provided below the holding table2and a table cover4(cover) vertically movably provided in the case3so as to surround the holding table2. The case3is composed of an outer wall portion31for surrounding an outer side surface of the table cover4, an inner wall portion32located inside the table cover4, and a bottom wall portion33connecting the outer wall portion31and the inner wall portion32at their lower ends. Accordingly, an annular space A1is defined by the outer wall portion31, the inner wall portion32, and the bottom wall portion33. This annular space A1is open to an upper side so that the cleaning fluid scattering from the holding table2during cleaning is allowed to flow into the annular space A1. The annular space A1functions also as a storing space for storing the table cover4in an inoperative condition of the cleaning apparatus1. The bottom wall portion33of the case3is fixed through a plurality of rubber cushions11to a base16.

The inner wall portion32of the case3has a cylindrical shape, and an inside space of the inner wall portion32is used as an installation space A2for the motor6for rotationally driving the holding table2. An upper opening of the installation space A2for the motor6is closed by an upper lid7. The upper lid7is fixed to an upper end of the inner wall portion32by a plurality of bolts71. The upper lid7has a substantially frustoconical shape having a slightly inclined conical surface. The upper lid7has a central hole72for insertion of a rotating shaft61of the motor6. An upper end of the upper lid7is formed with an annular projection73projecting toward the holding table2. The holding table2is rotatably supported to the annular projection73of the upper lid7. The motor6is fixed to a back side (lower surface) of the upper lid7by a plurality of bolts74.

The motor6is mounted on the upper lid7so as to depend therefrom. The rotating shaft61of the motor6projects upward from the upper end of the motor6so as to be inserted through the central hole72of the upper lid7. The upper portion of the rotating shaft61projects from the central hole72and is mounted to a lower portion of the holding table2, thereby transmitting a torque of the motor6to the holding table2. Further, the rotating shaft61of the motor6is formed with a suction passage (not shown), which is connected through a seal member14to a vacuum source15. The seal member14is provided by a magnetic seal, for example. The seal member14functions to rotatably support the rotating shaft61and connect the suction passage formed in the rotating shaft61to the vacuum source15. A holding member21of porous ceramic material is formed on an upper surface of the holding table2. A vacuum is produced on the holding member21by the vacuum source15to thereby hold the plate-shaped workpiece W on the holding member21under suction.

The outer wall portion31of the case3has a polygonal prismatic shape. The outer wall portion31has an outer side surface34on which a cylinder8for vertically moving the table cover4is mounted. The cylinder8contains a rod81. An upper end of the rod81projects from the cylinder8and is fixed to the table cover4. The rod81is provided with a piston82separating inside space of the cylinder8into an upper space and a lower space. A communication hole83for introducing air into the lower space below the piston82is formed at a lower end portion of the cylinder8. Similarly, a communication hole84for introducing air into the upper space above the piston82is formed at an upper end portion of the cylinder8. By passing air through the communication holes83and84, the table cover4is vertically moved through the rod81.

The table cover4has a boxlike shape, and it includes a top plate41for covering an upper side of the holding table2in a raised position of the table cover4(seeFIGS. 3A and 3B), a side plate42extending downward from an outer circumference of the top plate41, and a bottom plate43connected to a lower end of the side plate42for covering a lower side of the holding table2in the raised position. The top plate41is higher in level than an upper surface of the plate-shaped workpiece W held on the holding table2in the raised position of the table cover4. The top plate41has an opening44for allowing the holding table2to open to the upper side thereof. The opening44is formed by an opening projection45formed at a central portion of the top plate41so as to project obliquely upward toward the holding table2. With this configuration of the top plate41, the cleaning fluid scattering from the holding table2during cleaning is guided downward.

The top plate41is provided with a netlike mesh sheet46spaced from a whole lower surface of the top plate41. The mesh sheet46functions to absorb a cleaning fluid scattering from the holding table2and a mist floating from an under side of the holding table2. A space between the mesh sheet46and the lower surface of the top plate41is set to a sufficient space, so that there is no possibility that the cleaning fluid may be retained in the space between the mesh sheet46and the lower surface of the top plate41. Accordingly, the cleaning fluid absorbed by the mesh sheet46is not retained in the mesh sheet46, but quickly falls downward.

The side plate42has a polygonal prismatic shape similar to the shape of the outer wall portion31of the case3. The side plate42is also provided with a netlike mesh sheet47spaced from a whole inner surface of the side plate42. The mesh sheet47functions to absorb a cleaning fluid scattering from the holding table2. As similar to the mesh sheet46, a space between the mesh sheet47and the inner surface of the side plate42is set to a sufficient space, so that there is no possibility that the cleaning fluid may be retained in the space between the mesh sheet47and the inner surface of the side plate42. Accordingly, the cleaning fluid absorbed by the mesh sheet47is not retained in the mesh sheet47, but quickly falls downward.

The bottom plate43is located below the plate-shaped workpiece W held on the holding table2. In the raised position of the table cover4, the bottom plate43is positioned so as to cover the upper opening of the annular space A1of the case3. The bottom plate43of the table cover4is entirely formed with a plurality of holes48equally spaced from each other. The cleaning fluid absorbed by the mesh sheets46and47provided inside the top plate41and the side plate42is allowed to fall through the holes48of the bottom plate43into the annular space A1. Each of the mesh sheets46and47has a mesh size such that the cleaning fluid scattering from the holding table2is easily absorbed (caught) by the mesh sheets46and47and the cleaning fluid absorbed is quickly discharged from the mesh sheets46and47.

The rod81projecting from the cylinder8is fixed to an upper end portion of the outer side surface34of the side plate42. In the inoperative condition of the cleaning apparatus1, the table cover4is lowered so that the top plate41, the side plate42, and the bottom plate43are stored in the case3as shown inFIG. 2. In the operative condition of the cleaning apparatus1, the table cover4is raised so that a circumference of the holding table2is surrounded by the top plate41and the side plate42and the lower portion of the holding table2is covered with the bottom plate43as shown inFIGS. 3A and 3B. Accordingly, in the inoperative condition of the cleaning apparatus1, the holding table2is exposed from the table cover4as shown inFIG. 2, whereas in the operative condition of the cleaning apparatus1, the holding table2is surrounded by the holding table2to define a cleaning chamber A3as shown inFIGS. 3A and 3B.

The cleaning nozzle5for spraying a cleaning fluid to the plate-shaped workpiece W is located above the holding table2. The cleaning nozzle5is supported through an arm53to a rotating shaft52of a cleaning nozzle moving motor51. The cleaning nozzle5is adapted to rotate about an axis of the rotating shaft52by operating the cleaning nozzle moving motor51in such a manner that the cleaning nozzle5is oscillated between the center of the plate-shaped workpiece W and the outer circumference thereof. That is, the cleaning nozzle5operates to spray the cleaning fluid to the plate-shaped workpiece W held on the holding table2being rotated in the condition where the cleaning nozzle5is oscillated by the cleaning nozzle moving motor51. Accordingly, the cleaning fluid is sprayed onto the whole upper surface of the plate-shaped workpiece W to thereby clean off any soil sticking to the upper surface of the plate-shaped workpiece W.

In the cleaning apparatus1described above, the cleaning fluid scattering from the holding table2during cleaning of the plate-shaped workpiece W is absorbed by the mesh sheets46and47located inside the top plate41and the side plate42of the table cover4. That is, the cleaning fluid is absorbed by the mesh sheets46and47before reaching the side plate42and the top plate41, so that there is no possibility that the cleaning fluid may collide with the top plate41and the side plate42to produce a mist. Furthermore, the cleaning fluid absorbed by the mesh sheets46and47is allowed to continuously flow along the mesh sheets46and47and next fall down through the holes48of the bottom plate43into the annular space A1. Accordingly, the mesh sheets46and47are not saturated with the cleaning fluid absorbed, but can be always maintained in a cleaning fluid absorbable condition. As a result, even when the cleaning fluid scattering from the holding table2collides with the mesh sheets46and47, the cleaning fluid can be absorbed by the mesh sheets46and47without the production of a mist, so that an amount of a mist in the cleaning chamber A3can be suppressed.

The cleaning operation by the cleaning apparatus1according to this preferred embodiment will now be described with reference toFIGS. 3A to 3C.FIGS. 3A to 3Care views for illustrating the cleaning operation by the cleaning apparatus1. The cleaning operation shown inFIGS. 3A to 3Cis merely illustrative and it may be suitably modified.

As shown inFIG. 3A, the plate-shaped workpiece W is held under suction on the holding member21of the holding table2, and the table cover4is raised. Accordingly, the holding table2is surrounded by the table cover4to thereby define the cleaning chamber A3. At this time, the top plate41of the table cover4is positioned above the upper surface of the plate-shaped workpiece W held on the holding table2, and the bottom plate43of the table cover4is positioned below the holding table2so as to cover the annular space A1. In this raised position of the table cover4, the cleaning nozzle5is positioned inside the opening44of the top plate41, and the holding table2holding the plate-shaped workpiece W is rotated. In this condition, the cleaning fluid is sprayed from the cleaning nozzle5to the plate-shaped workpiece W.

The cleaning fluid sprayed onto the plate-shaped workpiece W is scattered from the holding table2by a centrifugal force. At this time, the cleaning fluid scattering from the holding table2is absorbed by the mesh sheets46and47located inside the top plate41and the side plate42. As described above, the mesh sheet46is sufficiently spaced from the lower surface of the top plate41, and the mesh sheet47is sufficiently spaced from the inner surface of the side plate42. Accordingly, the cleaning fluid absorbed by the mesh sheets46and47is easily discharged therefrom without an effect of a surface tension between the mesh sheet46and the lower surface of the top plate41and between the mesh sheet47and the inner surface of the side plate42.

As shown inFIG. 3B, the cleaning fluid absorbed by the mesh sheets46and47is allowed to continuously flow along the mesh sheets46and47and next fall down through the holes48of the bottom plate43into the annular space A1. As shown inFIG. 3C, each of the mesh sheets46and47is composed of innumerable vertical threads56and innumerable horizontal threads57to form a lattice-like network with innumerable meshes. Such a two-dimensional network can retain the cleaning fluid. This two-dimensional network has a retention force for the cleaning fluid smaller than that of a three-dimensional network such as a sponge. Further, in the two-dimensional network, the cleaning fluid is allowed to straight flow down on a plane. Accordingly, a discharge path of the cleaning fluid in the two-dimensional network is simpler than that in the three-dimensional network. As a result, the cleaning fluid once absorbed by the mesh sheets46and47can be discharged in a shorter time as compared with the case of using an absorbing member having a three-dimensional network structure such as a sponge.

The cleaning fluid absorbed by the mesh sheets46and47is allowed to continuously flow down, so that the condition where the cleaning fluid has been absorbed by the mesh sheets46and47can be quickly returned to the condition where the cleaning fluid has been discharged from the mesh sheets46and47. In this manner, the absorption and the discharge of the cleaning fluid are continuously repeated in the mesh sheets46and47, so that the mesh sheets46and47are not saturated with the cleaning fluid. Accordingly, the cleaning fluid scattering from the holding table2can be continuously absorbed by the mesh sheets46and47, so that even when the cleaning fluid collides with the mesh sheets46and47, no mist is produced. Further, the cleaning fluid absorbed by the mesh sheets46and47does not become a mist, but falls down through the holes48of the bottom plate43into the annular space A1. Thereafter, the cleaning fluid is discharged from a drain outlet35(seeFIG. 2) provided at a lower end portion of the outer wall portion31of the case3. Accordingly, it is unnecessary to provide any forced draft equipment on the case3. Thus, the production of a mist can be effectively suppressed by the simple configuration that the mesh sheets46and47are provided inside the top plate41and the side plate42of the table cover4.

According to the cleaning apparatus1described above, the cleaning fluid scattering from the holding table2during cleaning does not collide with the top plate41and the side plate42of the table cover4, but it is absorbed by the mesh sheets46and47provided inside the top plate41and the side plate42of the table cover4. Accordingly, there is no possibility that a mist is produced due to the collision of the cleaning fluid with the top plate41and the side plate42, thereby suppressing the production of a mist in the table cover4. Further, when the cleaning fluid is absorbed by the mesh sheets46and47, the cleaning fluid retained in the network of the mesh sheets46and47is allowed to flow down along the network. That is, the cleaning fluid absorbed by the mesh sheets46and47is allowed to continuously fall down along the network, so that the mesh sheets46and47are not saturated with the cleaning fluid, but they can be always maintained in a cleaning fluid absorbable condition. Accordingly, there is no possibility that the cleaning fluid colliding the mesh sheets46and47may become a mist.

The present invention is not limited to the above preferred embodiment, but various modifications may be made. The size, shape, etc. of any part shown in the attached drawings are merely illustrative and they may be suitably changed within the scope where the effect of the present invention can be exhibited. Further, the above preferred embodiment may be suitably modified without departing from the scope of the object of the present invention.

For example, while the cleaning nozzle5in the cleaning apparatus1is pivotably oscillated so as to spray the cleaning fluid to the whole surface of the plate-shaped workpiece W in the above preferred embodiment, the present invention is not limited to this configuration provided that the cleaning fluid is sprayed to the plate-shaped workpiece W to thereby clean the workpiece W. For example, in the case that the plate-shaped workpiece W is a workpiece processed by edge trimming, the cleaning fluid may be sprayed to only the outer circumference of the plate-shaped workpiece W.

While the table cover4is vertically movable in the above preferred embodiment, the table cover4may be fixed at the raised position so as to always surround the holding table2. Further, while the mesh sheets46and47are provided inside the top plate41and the side plate42of the table cover4in the above preferred embodiment, it is essential that at least the mesh sheet46is to be provided inside the side plate42of the table cover4.

Further, while the bottom plate43is included in the table cover4in the above preferred embodiment, it is essential that at least the top plate41and the side plate42are to be included in the table cover4. Also with such a configuration, the production of a mist can be effectively prevented. Further, while each of the mesh sheets46and47forms a lattice-like network in the above preferred embodiment, the shape of the network is not especially limited provided that each of the mesh sheets46and47has a two-dimensional network structure.

In the above preferred embodiment, the single mesh sheet46is provided inside the top plate41and the single mesh sheet47is provided inside the side plate42. However, a plurality of mesh sheets46spaced a predetermined distance from each other may be provided inside the top plate41. Similarly, a plurality of mesh sheets47spaced a predetermined distance from each other may be provided inside the side plate42.

According to the present invention, the production of a mist can be effectively prevented by the simple configuration that the mesh sheet is provided inside the side plate of the cover. In particular, the present invention is useful as a cleaning apparatus for cleaning off any soil on a whole surface of a plate-shaped workpiece.