CLEANING DEVICE

Abstract

Cleaning device, which includes: a holding table for holding a flat workpiece; a motor for rotating the holding table; a cleaning nozzle for spraying a cleaning fluid onto the plate-shaped workpiece held on the holding table; and a cover to absorb the cleaning fluid that was sprayed from the cleaning nozzle and distributed by the holding table, which holds the plate-shaped workpiece and rotates at a predetermined speed, wherein the cover comprises a top plate with an opening for exposing an upper surface of the holding table and a side plate connected to the top plate in such a way that it extends downwards from the top plate, and the top plate is arranged above an upper surface of the plate-shaped workpiece held on the holding table, wherein the side plate is provided with a net-like grid track which is spaced away from an inner surface of the side plate.

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The present invention relates to a cleaning device for cleaning the surface of a plate-shaped workpiece, such as a semiconductor wafer. Description of the state of the art

[0002] A centrifugal cleaning device is generally known that includes a rotating holding table for a wafer and a cleaning nozzle for spraying a cleaning fluid onto the wafer, which is held on the rotating holding table (see, for example, Japanese patent application JP 2009-94247A). In the cleaning device described in Japanese patent application JP 2009-94247A, the cleaning nozzle pivots back and forth above the holding table as the cleaning fluid is sprayed onto the wafer, thereby removing contaminants adhering to the entire surface of the wafer. Because the cleaning fluid is sprayed onto the rotating wafer, it is distributed across the wafer by centrifugal force.To manage this distribution of the cleaning fluid, a distribution prevention cover is provided that is vertically movable and surrounds the holding table, whereby the distribution prevention cover is raised in an operating state of the cleaning device in order to prevent the distribution of the cleaning fluid.

[0003] US 2005 / 0284362A1 relates to a substrate surface treatment device.

[0004] JP 2006- 32 637 A concerns a substrate cleaning device.

[0005] JP S63-294966A relates to a coating device. SUMMARY OF THE INVENTION

[0006] A sponge is provided on an inner surface of the distribution-prevention cover in the cleaning device to absorb the cleaning fluid dispersed by the holding table. Because the sponge has a three-dimensional network structure, the cleaning fluid is easily absorbed. However, the cleaning fluid absorbed by the sponge is difficult to remove. Consequently, the removal rate of the cleaning fluid absorbed by the sponge is low, and when the sponge becomes saturated with cleaning fluid, a problem arises in that the cleaning fluid impacting the sponge can become mist, which can adhere to the wafer or holding table.

[0007] It is therefore an objective of the present invention to provide a cleaning device which, with a simple design, can effectively prevent the generation of haze.

[0008] According to one aspect of the present invention, a cleaning device is provided comprising: a holding table for holding a plate-shaped workpiece; a motor for rotating the holding table; a cleaning nozzle for spraying a cleaning fluid onto the plate-shaped workpiece held on the holding table; and a cover for absorbing the cleaning fluid sprayed from the cleaning nozzle and distributed by the holding table, which holds the plate-shaped workpiece and rotates at a predetermined speed. The cover comprises an upper plate with an opening for exposing an upper surface of the holding table and a side plate connected to the upper plate in such a way that it extends downwards from the upper plate. The upper plate is positioned above an upper surface of the plate-shaped workpiece held on the holding table.The side plate is provided with a net-like grid pattern that is spaced away from an inner surface of the side plate.

[0009] In this setup, the cleaning fluid dispensed from the holding table during cleaning does not come into contact with the side panel of the cover, but is absorbed by the grid, which is spaced away from the inner surface of the cover's side panel. Consequently, there is no possibility of mist being generated by the cleaning fluid striking the side panel. Furthermore, when the cleaning fluid is absorbed by the grid, it can flow downwards along the grid. Because the cleaning fluid absorbed by the grid can continuously sink downwards, the grid does not become saturated with the cleaning fluid, but can always be kept in a state where it is capable of absorbing more cleaning fluid.Accordingly, there is no possibility that the cleaning fluid hitting the grid track can turn into vapor.

[0010] According to the present invention, the generation of haze can be effectively prevented by the simple design in which the grid is provided on the inside of the side plate of the cover.

[0011] The above and further aims, features and advantages of the present invention and the manner in which they are realized will become more apparent, and the invention itself will be best understood by studying the following description and the attached claims with reference to the accompanying drawings, which show some preferred embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic top view of a cleaning device according to a preferred embodiment of the present invention; Fig. 2 is a schematic sectional view of the cleaning device along a line AA in Fig. 1; and Fig. Figures 3A to 3C are views illustrating a cleaning process by the cleaning device. DETAILED DESCRIPTION OF THE PREFERRED EXECUTION FORM

[0012] A preferred embodiment of the present invention is described in detail below with reference to the accompanying drawings. Fig. Figure 1 is a schematic top view of a cleaning device 1 according to this preferred embodiment. Fig. 2 is a schematic sectional view of the cleaning device 1 along a line AA in Fig. 1. A structure of the in Fig. The cleaning device shown in Figure 1 is for illustrative purposes only and can be modified as needed. Fig. Figure 1 does not show a cleaning nozzle for the sake of simplicity.

[0013] As in the Fig. 1 and Fig. As shown in Figure 2, the cleaning device 1 comprises a holding table 2 for holding a plate-shaped workpiece W, a motor 6 for rotating the holding table 2, and a cleaning nozzle 5 for spraying a cleaning fluid onto the plate-shaped workpiece W held on the holding table 2 during rotation of the holding table 2. The cleaning device 1 is used to clean the plate-shaped workpiece W after various types of machining, such as grinding, polishing, edge trimming, and partial grinding, except on a circumferential section of the workpiece W. The plate-shaped workpiece W can be a semiconductor wafer made of silicon, gallium arsenide, etc., or an inorganic material substrate made of ceramic, glass, sapphire (Al₂O₃), etc.

[0014] The cleaning device 1 further comprises a housing 3 located below the holding table 2 and a table cover 4 (cover) which is vertically movable within the housing 3 and surrounds the holding table 2. The housing 3 consists of an outer wall section 31 for surrounding an outer side surface of the table cover 4, an inner wall section 32 located inside the table cover 4, and a lower wall section 33 connecting the outer wall section 31 and the inner wall section 32 at their lower ends. Accordingly, an annular space A1 is defined by the outer wall section 31, the inner wall section 32, and the lower wall section 33. This annular space A1 is open at the top so that the cleaning fluid, which is distributed from the holding table 2 during cleaning, can flow into the annular space A1.The ring-shaped space A1 also acts as a receiving space for the table cover 4 when the cleaning device 1 is in a resting state. The lower wall section 33 of the housing 3 is attached to a base 16 by several rubber buffers 11.

[0015] The inner wall section 32 of the housing 3 has a cylindrical shape, and an inner space of the inner wall section 32 serves as a mounting space A2 for the motor 6 for the rotary drive of the holding table 2. An upper opening of the mounting space A2 for the motor 6 is closed by an upper cover 7. The upper cover 7 is fastened to an upper end of the inner wall section 32 by several bolts 71. The upper cover 7 has a substantially frustoconical shape with a slightly inclined conical surface. The upper cover 7 has a central opening 72 for inserting a rotary shaft 61 of the motor 6. An upper end of the upper cover 7 is formed with an annular projection 73 that extends toward the holding table 2. The holding table 2 is rotatably mounted on the annular projection 73 of the upper cover 7.The motor 6 is attached to a rear (lower surface) of the upper cover 7 by several bolts 74.

[0016] The motor 6 is attached to the upper cover 7 in such a way that it hangs from it. The rotating shaft 61 of the motor 6 projects upwards from the upper end of the motor 6 so that it is inserted through the central opening 72 of the upper cover 7. The upper section of the rotating shaft 61 projects from the central opening 72 and is attached to a lower section of the support table 2, thereby transmitting a rotational force from the motor 6 to the support table 2. Furthermore, the rotating shaft 61 of the motor 6 is provided with an intake port (not shown) which is connected to a vacuum source 15 by a sealing element 14. The sealing element 14 is, for example, a magnetic seal. The sealing element 14 acts in such a way that it holds the rotating shaft 61 rotatably and connects the intake port formed in the rotating shaft 61 to the vacuum source 15. A holding element 21 made of porous ceramic material is formed on an upper surface of the holding table 2.A vacuum is generated by the vacuum source 15 at the holding element 21 in order to hold the plate-shaped workpiece W against the holding element 21 by suction.

[0017] The outer wall section 31 of the housing 3 has a polygonal prism shape. The outer wall section 31 has an outer side surface 34 to which a cylinder 8 for vertically moving the table cover 4 is attached. The cylinder 8 contains a rod 81. An upper end of the rod 81 projects from the cylinder 8 and is attached to the table cover 4. The rod 81 is provided with a piston 82, which divides the inner space of the cylinder 8 into an upper and a lower space. A communication opening 83 for introducing air into the lower space below the piston 82 is formed at a lower end section of the cylinder 8. Similarly, a communication opening 84 for introducing air into the upper space above the piston 82 is formed at an upper end section of the cylinder 8. By introducing air through the communication openings 83 and 84, the rod 81 moves the table cover 4 vertically.

[0018] The table cover 4 has a box-like shape and includes a top plate 41 for covering an upper side of the support table 2 in a raised position of the table cover 4 (see Fig. 3A and Fig. 3B), a side plate 42 extending downwards from an outer circumference of the upper plate 41, and a lower plate 43 connected to a lower end of the side plate 42, for covering a lower side of the holding table 2 in the raised position. In the raised position of the table cover 4, the upper plate 41 lies at a higher level than the upper surface of the plate-shaped workpiece W held on the holding table 2. The upper plate 41 has an opening 44 that allows the holding table 2 to open towards its upper side. The opening 44 is formed by an opening projection 45, which is formed on a central section of the upper plate 41 such that it projects obliquely upwards towards the holding table 2. This design of the upper plate 41 directs the cleaning fluid, which is distributed from the holding table 2 during cleaning, downwards.

[0019] The upper plate 41 is provided with a mesh-like grid 46, which is spaced away from the entire lower surface of the upper plate 41. The grid 46 acts in such a way that it absorbs a cleaning fluid distributed by the holding table 2 and a mist rising from the lower side of the holding table 2. A space between the grid 46 and the lower surface of the upper plate 41 is provided that is sufficiently large so that there is no possibility of the cleaning fluid being retained in the space between the grid 46 and the lower surface of the upper plate 41. Accordingly, the cleaning fluid absorbed by the grid 46 is not retained in the grid 46, but rather sinks rapidly downwards.

[0020] The side plate 42 has a polygonal prism shape similar to the shape of the outer wall section 31 of the housing 3. The side plate 42 is also provided with a mesh-like grid track 47, which is spaced away from the entire inner surface of the side plate 42. The grid track 47 acts in such a way that it absorbs a cleaning fluid distributed from the holding table 2. Similar to the grid track 46, a space between the grid track 47 and the inner surface of the side plate 42 is set to be sufficiently large so that there is no possibility of the cleaning fluid being retained in the space between the grid track 47 and the inner surface of the side plate 42. Accordingly, the cleaning fluid absorbed by the grid track 47 is not retained in the grid track 47, but rather sinks rapidly downwards.

[0021] The lower plate 43 is arranged below the plate-shaped workpiece W, which is held on the holding table 2. In the raised position of the table cover 4, the lower plate 43 is positioned so that it covers the upper opening of the annular space A1 of the housing 3. The lower plate 43 of the table cover 4 is entirely formed with several openings 48, which are equidistant from one another. The cleaning fluid, which is absorbed by the grids 46 and 47 provided within the upper plate 41 and the side plate 42, can drain through the openings 48 of the lower plate 43 into the annular space A1. Each of the grids 46 and 47 has a mesh size such that the cleaning fluid distributed by the holding table 2 is easily absorbed (collected) by the grids 46 and 47, and the absorbed cleaning fluid is quickly drained away by the grids 46 and 47.

[0022] The rod 81 projecting from the cylinder 8 is attached to an upper end section of the outer side surface 34 of the side plate 42. In the resting state of the cleaning device 1, the table cover 4 is lowered so that the upper plate 41, the side plate 42 and the lower plate 43 are received in the housing 3, as shown in Fig. Figure 2 shows that in the operating state of the cleaning device 1, the table cover 4 is raised so that one perimeter of the holding table 2 is surrounded by the upper plate 41 and the side plate 42, and the lower section of the holding table 2 is covered by the lower plate 43, as shown in Figure 2. Fig. 3A and Fig. Figure 3B shows that, accordingly, the holding table 2 is exposed from the table cover 4 in the resting state of the cleaning device 1, as shown in Figure 3B. Fig. 2 is shown, while in the operating state of the cleaning device 1 the holding table 2 is surrounded by the holding table 2 to define a cleaning chamber A3, as in Fig. 3A and Fig. 3B is shown.

[0023] The cleaning nozzle 5, for spraying a cleaning fluid onto the flat workpiece W, is arranged above the holding table 2. The cleaning nozzle 5 is held by an arm 53 on a rotating shaft 52 of a cleaning nozzle motion motor 51. The cleaning nozzle 5 is designed to rotate about an axis of the rotating shaft 52 by operating the cleaning nozzle motion motor 51 in such a way that the cleaning nozzle 5 is moved back and forth between the center of the flat workpiece W and its outer circumference. That is, the cleaning nozzle 5 operates in such a way that it sprays the cleaning fluid onto the flat workpiece W, which is held on the rotating holding table 2, in the state in which the cleaning nozzle 5 is moved back and forth by the cleaning nozzle motion motor 51.Accordingly, the cleaning fluid is sprayed onto the entire upper surface of the plate-shaped workpiece W in order to remove any contamination adhering to the upper surface of the plate-shaped workpiece W.

[0024] In the cleaning device 1 described above, the cleaning fluid, which is distributed from the holding table 2 during the cleaning of the plate-shaped workpiece W, is absorbed by the grid tracks 46 and 47 arranged within the upper plate 41 and the side plate 42 of the table cover 4. That is, the cleaning fluid is absorbed by the grid tracks 46 and 47 before it reaches the side plate 42 and the upper plate 41, so that there is no possibility of the cleaning fluid coming into contact with the upper plate 41 and the side plate 42, thus preventing the formation of mist. Furthermore, the cleaning fluid absorbed by the grid tracks 46 and 47 can flow continuously along the grid tracks 46 and 47 and then sink through the openings 48 of the lower plate 43 into the annular space A1.Accordingly, the grid tracks 46 and 47 are not saturated with the absorbed cleaning fluid, but can always be kept in a state in which they are capable of absorbing cleaning fluid. As a result, even when the cleaning fluid distributed from the holding table 2 strikes the grid tracks 46 and 47, the cleaning fluid can be absorbed by the grid tracks 46 and 47 without generating mist, thus suppressing the formation of mist in the cleaning chamber A3.

[0025] The cleaning process by the cleaning device 1 according to this preferred embodiment is described below with reference to the Fig. 3A to 3C described. Fig. Figures 3A to 3C are views illustrating the cleaning process by cleaning device 1. The one shown in the Fig. The cleaning process shown in 3A to 3C is for illustrative purposes only and can be modified as appropriate.

[0026] As in Fig. As shown in Figure 3A, the flat workpiece W is held by suction against the holding element 21 of the holding table 2, and the table cover 4 is raised. The holding table 2 is thus enclosed by the table cover 4, defining the cleaning chamber A3. At this point, the upper plate 41 of the table cover 4 is positioned above the upper surface of the flat workpiece W held on the holding table 2, and the lower plate 43 of the table cover 4 is positioned below the holding table 2, covering the annular space A1. In this raised position of the table cover 4, the cleaning nozzle 5 is positioned within the opening 44 of the upper plate 41, and the holding table 2, which holds the flat workpiece W, is rotated. In this state, the cleaning fluid is sprayed from the cleaning nozzle 5 onto the flat workpiece W.

[0027] The cleaning fluid sprayed onto the plate-shaped workpiece W is distributed by the holding table 2 by a centrifugal force. At this point, the cleaning fluid distributed by the holding table 2 is absorbed by the grid tracks 46 and 47 arranged within the upper plate 41 and the side plate 42. As described above, the grid track 46 is sufficiently spaced from the lower surface of the upper plate 41, and the grid track 47 is sufficiently spaced from the inner surface of the side plate 42. Accordingly, the cleaning fluid absorbed by the grid tracks 46 and 47 is easily carried away from them without any surface tension effect between the grid track 46 and the lower surface of the upper plate 41 or between the grid track 47 and the inner surface of the side plate 42.

[0028] As in Fig. As shown in Figure 3B, the cleaning fluid absorbed by the grid lines 46 and 47 can flow continuously along the grid lines 46 and 47 and then sink through the openings 48 of the lower plate 43 into the annular space A1. As shown in Fig. As shown in Figure 3C, each of the lattice paths 46 and 47 consists of a large number of vertical strands 56 and a large number of horizontal strands 57 to form a grid-like network with a large number of meshes. Such a two-dimensional network can retain the cleaning fluid. This two-dimensional network exhibits a holding force for the cleaning fluid that is smaller than that of a three-dimensional network, such as a sponge. Furthermore, in the two-dimensional network, the cleaning fluid can flow directly downwards in a plane. Accordingly, a drainage path for the cleaning fluid is simpler in the two-dimensional network than in the three-dimensional network.As a result, once the cleaning fluid has been absorbed through the lattice pathways 46 and 47, it can be removed in a shorter time compared to the case of using an absorption element with a three-dimensional network structure, such as a sponge.

[0029] The cleaning fluid absorbed by the grid tracks 46 and 47 can flow continuously downwards, so that the state in which the cleaning fluid was absorbed by the grid tracks 46 and 47 can be quickly returned to the state in which the cleaning fluid was discharged from the grid tracks 46 and 47. In this way, the absorption and discharge of the cleaning fluid are continuously repeated in the grid tracks 46 and 47, so that the grid tracks 46 and 47 do not become saturated with the cleaning fluid. Accordingly, the cleaning fluid distributed by the holding table 2 can be continuously absorbed by the grid tracks 46 and 47, so that even when the cleaning fluid impacts the grid tracks 46 and 47, no mist is generated.Furthermore, the cleaning fluid absorbed by the grid tracks 46 and 47 does not evaporate, but sinks downwards through the openings 48 of the lower plate 43 into the annular space A1. The cleaning fluid is then discharged from a drain 35 (see . Fig. 2) discharged, which is provided at a lower end section of the outer wall section 31 of the housing 3. Accordingly, it is not necessary to provide a suction air device on the housing 3. Therefore, the generation of mist can be effectively suppressed by the simple design in which the grid tracks 46 and 47 are provided within the upper plate 41 and the side plate 42 of the table cover 4.

[0030] According to the cleaning device 1 described above, the cleaning fluid distributed from the holding table 2 during cleaning does not come into contact with the upper plate 41 and the side plate 42 of the table cover 4, but is absorbed by the grid channels 46 and 47 provided within the upper plate 41 and the side plate 42 of the table cover 4. Accordingly, there is no possibility of mist being generated due to the cleaning fluid coming into contact with the upper plate 41 and the side plate 42, thus suppressing the generation of mist in the table cover 4. Furthermore, when the cleaning fluid is absorbed by the grid channels 46 and 47, the cleaning fluid contained within the network of grid channels 46 and 47 can flow downwards along the network.This means that the cleaning fluid absorbed by the grid lines 46 and 47 can sink continuously downwards along the network, so that the grid lines 46 and 47 do not become saturated with the cleaning fluid, but can always be kept in a state in which they can absorb cleaning fluid. Accordingly, there is no possibility that the cleaning fluid impacting the grid lines 46 and 47 can turn into vapor.

[0031] The present invention is not limited to the preferred embodiment described above, but various modifications are possible. The size, shape, etc., of each part shown in the accompanying drawings serve only for illustration and can be suitably modified within the scope necessary to achieve the desired effect of the present invention. Furthermore, the preferred embodiment described above can be suitably modified without deviating from the scope of the present invention.

[0032] For example, although in the preferred embodiment above the cleaning nozzle 5 is pivoted back and forth in the cleaning device 1 so that it sprays the cleaning fluid onto the entire surface of the plate-shaped workpiece W, the present invention is not limited to this configuration, provided that the cleaning fluid is sprayed onto the plate-shaped workpiece W in order to clean the workpiece W. For example, if the plate-shaped workpiece W is a workpiece machined by edge trimming, the cleaning fluid can be sprayed only onto the outer circumference of the plate-shaped workpiece W.

[0033] Although in the preferred embodiment above the table cover 4 is vertically movable, it can be fixed in the raised position so that it always surrounds the support table 2. Furthermore, although in the preferred embodiment above the grid tracks 46 and 47 are provided within the upper plate 41 and the side plate 42 of the table cover 4, it is essential that at least the grid tracks 46 are provided within the side plate 42 of the table cover 4.

[0034] Furthermore, although in the preferred embodiment above the lower plate 43 is included in the table cover 4, it is essential that at least the upper plate 41 and the side plate 42 are included in the table cover 4. Even with such a construction, the generation of mist can be effectively prevented. Furthermore, although in the preferred embodiment above each of the grid lines 46 and 47 forms a grid-like network, the shape of the network is not particularly restricted, provided that each of the grid lines 46 and 47 has a two-dimensional network structure.

[0035] In the preferred embodiment described above, the single grid track 46 is provided within the upper plate 41 and the single grid track 47 is provided within the side plate 42. However, several grid tracks 46, spaced apart from each other by a predetermined distance, can be provided within the upper plate 41. Similarly, several grid tracks 47, spaced apart from each other by a predetermined distance, can be provided within the side plate 42.

[0036] According to the present invention, the generation of mist can be effectively prevented by the simple design in which the grid is provided within the side plate of the cover. In particular, the present invention can be used as a cleaning device for removing contamination from the entire surface of a plate-shaped workpiece.

Claims

[1] Cleaning device comprising: a holding table for holding a flat workpiece; a motor for rotating the holding table; a cleaning nozzle for spraying a cleaning fluid onto the plate-shaped workpiece held on the holding table; and a cover to absorb the cleaning fluid that was sprayed from the cleaning nozzle and distributed by the holding table, which holds the plate-shaped workpiece and rotates at a predetermined speed, wherein the cover comprises a top plate with an opening for exposing an upper surface of the holding table and a side plate connected to the top plate in such a way that it extends downwards from the top plate, and the top plate is arranged above an upper surface of the plate-shaped workpiece held on the holding table, wherein the side plate is provided with a net-like grid track which is spaced away from an inner surface of the side plate. [2] Cleaning device according to claim 1, wherein the upper plate is provided with a further mesh-like grid track which is spaced apart from a lower surface of the upper plate.

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