GRINDING APPARATUS

A grinding apparatus includes a loading unit for loading a wafer to a chuck table having a holding surface for holding the wafer, an unloading unit for unloading the wafer from the chuck table, and a cleaning unit for cleaning the holding surface of the chuck table or the upper surface of the wafer held on the holding surface of the chuck table. The cleaning unit includes a cleaning portion and a horizontal moving portion for horizontally moving the cleaning portion in a lateral direction of the grinding apparatus. The loading unit has a first holding portion for holding the wafer, and the unloading unit has a second holding portion for holding the wafer.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a grinding apparatus.

Description of the Related Art

In the operation of a grinding apparatus, a robot is first operated to draw a wafer out of a cassette storing a plurality of wafers supported on shelves. Thereafter, the wafer is transferred to a temporary setting table by the robot and then positioned on the temporary setting table. Thereafter, loading means having a swing arm and a loading pad is operated to load the wafer from the temporary setting table to a chuck table having a holding surface for holding the wafer. Thereafter, the wafer held on the chuck table is ground by using a grinding wheel having abrasive members. Thereafter, a cleaning unit is operated to spray a two-component fluid composed of air and water toward the upper surface (work surface) of the wafer ground by the abrasive members of the grinding wheel, thereby cleaning the upper surface of the wafer. Thereafter, unloading means having a swing arm and an unloading pad is operated to unload the wafer from the chuck table to a spinner. Thereafter, the spinner is operated to rotate the wafer as supplying a cleaning water to the wafer, thereby cleaning the wafer and next drying it by using a centrifugal force. Thereafter, the robot is operated again to store the wafer into the cassette. Thus, a series of grinding operation for the wafer is finished.

The loading pad of the loading means has a holding surface for holding the upper surface of the wafer to be ground, and the lower surface of the wafer held on the holding surface of the loading pad is cleaned by a lower surface cleaning unit provided in a loading path where the loading means is moved (see Japanese Patent Laid-Open Nos. 2015-199158, 2011-018802, and 2010-094785, for example). Similarly, the unloading pad of the unloading means has a holding surface for holding the upper surface of the wafer ground, and the lower surface of the wafer held on the holding surface of the unloading pad is cleaned by another lower surface cleaning unit provided in an unloading path where the unloading means is moved. Further, the grinding apparatus includes an unloading pad cleaning unit for cleaning the holding surface of the unloading pad in the condition where the wafer is not held on the holding surface of the unloading pad, whereby the holding surface of the unloading pad is suitably cleaned.

The cleaning unit for cleaning the upper surface of the wafer ground includes a two-fluid cleaning portion for spraying the two-component fluid mentioned above to the holding surface of the chuck table or the upper surface of the wafer ground, thereby cleaning the holding surface of the chuck table or the upper surface of the wafer ground and also includes an abrasive cleaning portion having cleaning abrasive members adapted to come into contact with the holding surface of the chuck table, thereby scraping grinding dust off the holding surface of the chuck table. Thus, the holding surface of the chuck table is also cleaned by the cleaning unit.

SUMMARY OF THE INVENTION

In the past, the cleaning unit has been provided with an elevating mechanism for vertically moving the cleaning unit in a large amount, so as to avoid the possibility that the cleaning unit may collide with the loading means for loading the wafer to the chuck table before grinding or the unloading means for unloading the wafer from the chuck table after grinding. However, when the two-fluid cleaning portion and the abrasive cleaning portion of the cleaning unit are being vertically moved by operating the elevating mechanism, the loading means and the unloading means must wait, causing a bottleneck in reducing the operation time required for grinding. That is, there is a problem such that the operation time for grinding is increased by the vertical movement of the cleaning unit. Further, when the loading means and the unloading means are waiting, it is desired that the wafer to be ground can be set on the temporary setting table and that the wafer ground can be cleaned by the spinner, thereby improving the productivity.

It is therefore an object of the present invention to provide a grinding apparatus which can eliminate the above problem due to the waiting of the loading means and the unloading means during the vertical movement of the two-fluid cleaning portion and the abrasive cleaning portion of the cleaning unit.

In accordance with an aspect of the present invention, there is provided a grinding apparatus for grinding a wafer having an upper surface and a lower surface, the grinding apparatus including a chuck table having a holding surface for holding the wafer; a grinding unit having a rotatable grinding wheel for grinding the wafer held on the holding surface of the chuck table, the grinding wheel having a plurality of abrasive members arranged annularly and adapted to come into contact with the upper surface of the wafer, whereby when the grinding wheel is rotated and the abrasive members come into contact with the upper surface of the wafer held on the holding surface of the chuck table, the upper surface of the wafer is ground by the abrasive members; loading means provided at one side portion of the grinding apparatus in a lateral direction thereof for loading the wafer to the chuck table before grinding; unloading means provided at the other side portion of the grinding apparatus in the lateral direction for unloading the wafer from the chuck table after grinding; a cleaning unit for cleaning the holding surface of the chuck table or the upper surface of the wafer held on the holding surface of the chuck table; and a control unit for controlling ail of the chuck table, the grinding unit, the loading means, the unloading means, and the cleaning unit; the loading means including a first holding portion for holding the wafer before grinding and first horizontal moving means for horizontally moving the first holding portion; the unloading means including a second holding portion for holding the wafer after grinding and second horizontal moving means for horizontally moving the second holding portion; the cleaning unit including a cleaning portion For clearing the holding surface of the chuck table or the upper surface of the wafer held on the holding surface of the chuck table and third horizontal moving means for horizontally moving the cleaning portion in the lateral direction; whereby when the wafer is unloaded from the holding surface of the chuck table by the unloading means after grinding, the third horizontal moving means is operated by the control unit to horizontally move the cleaning portion toward the first holding portion in a first direction, thereby allowing the unloading of the wafer from the holding surface of the chuck table by the unloading means after grinding; and when the wafer is loaded to the holding surface of the chuck table by the loading means before grinding, the third horizontal moving means is operated by the control unit to horizontally move the cleaning portion toward the second holding portion in a second direction opposite to the first direction, thereby allowing the loading of the wafer to the holding surface of the chuck table by the loading means before grinding.

Preferably, the grinding apparatus further includes a first lower surface cleaning unit for cleaning the lower surface of the wafer held by the first holding portion of the loading means before grinding; the first lower surface cleaning unit being located on a path of movement of the wafer by the loading means; whereby while the lower surface of the wafer is being cleaned by the first lower surface cleaning unit before grinding, the unloading of the wafer from the holding surface of the chuck table by the unloading means after grinding is allowed.

Preferably, the grinding apparatus further includes a second lower surface cleaning unit for cleaning the lower surface of the wafer held by the second holding portion of the unloading means after grinding; the second lower surface cleaning unit being located on a path of movement of the wafer by the unloading means; whereby while the lower surface of the wafer being cleaned by the second lower surface cleaning unit after grinding, the loading of the wafer to the holding surface of the chuck table by the loading means before grinding is allowed.

Preferably, the second holding portion of the unloading means has a holding surface for holding the upper surface of the wafer after grinding; the second lower surface cleaning unit including a holding surface cleaning portion for cleaning the holding surface of the second holding portion of the unloading means.

As described above, the cleaning portion is horizontally moved in the lateral direction of the grinding apparatus so as to avoid the collision with the loading means and the unloading means in loading and unloading the wafer. Accordingly, it is unnecessary to vertically move the cleaning portion, so as to ensure the path of movement of the wafer by the loading means and the unloading means, so that the time required for transfer of the wafer by the loading means and the unloading means can be reduced. Accordingly, the cleaning time can be extended. Further, a receptacle for receiving a cleaning water from the cleaning portion is not required.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

1. Configuration of Grinding Apparatus

Referring toFIG. 1, there is depicted a grinding apparatus1in plan. The grinding apparatus1is an apparatus for grinding a wafer W as a plate-shaped semiconductor workpiece by using a first grinding unit7and a second grinding unit8. The wafer W has an upper surface Wa and a lower surface Wb. The configuration of the grinding apparatus1will now be described. In the following description, the X direction includes the +X direction depicted by an arrow +X in the drawings and the −X direction depicted by an arrow −X in the drawings. Similarly, the Y direction includes the +Y direction depicted by an arrow −Y in the drawings and the −Y direction depicted by an arrow −Y in the drawings. Further, the Z direction includes the +Z direction depicted by an arrow in the drawings and the −Z direction depicted by an arrow −Z in the drawings. The X direction and the Y direction are perpendicular to each other to define a horizontal plane, and the Z direction is perpendicular to this horizontal plane.

As depicted inFIG. 1, the grinding apparatus1includes a base10having a substantially rectangular shape elongated in the Y direction. That is, a lateral direction of the grinding apparatus1is parallel to the X direction, and a longitudinal direction of the grinding apparatus1is parallel to the Y direction. A control unit11is connected to the grinding apparatus1, and electrical signals are adapted to be transmitted from the control unit11to various mechanisms included in the grinding apparatus1, thereby controlling the grinding apparatus1. The upper surface of the base10in its front portion (in the −Y direction) is set as a standby area A where the wafer W is loaded or unloaded, and the upper surface of the base10at its rear portion (in the +Y direction) is set as a grinding area B where the wafer W is ground.

A first cassette15and a second cassette16are provided in the standby area A at the front end thereof. The first cassette15functions to store a plurality of wafers W1before grinding, and the second cassette16functions to store a plurality of wafers W2after grinding. That is, each wafer W1(seeFIG. 2A) is the wafer W to be ground by the first grinding unit7and the second grinding unit8, and each wafer W2(seeFIG. 5A) is the wafer W ground by the first grinding unit7and the second grinding unit8. A robot12is provided in the standby area A. The robot12functions to draw each wafer W1out of the first cassette15before grinding and also to insert each wafer W2into the second cassette16after grinding.

Further, a temporary setting table13is provided in the standby area A. The wafer W (wafer W1) drawn out of the first cassette15by the robot12is transferred to the temporary setting table13by the robot12and then placed in position on the temporary setting table13.

In addition, a spinner14as a single-wafer cleaning mechanism for cleaning the wafer W (wafer W2) after grinding is also provided in the standby area A.

Further, loading means3and unloading means4are provided in an area between the standby area A and the grinding area B. The loading means3functions to transfer the wafer W (wafer W1) from the standby area A to the grinding area B before grinding. The unloading means4functions to transfer the wafer W (wafer W2) from the grinding area3to the standby area A after grinding.

The loading means3includes a first holding portion30for holding the wafer (wafer W1). The first holding portion30may be configured by a suction pad, Bernoulli pad, or edge clamp, for example. The loading means3further Includes a first arm31and first swinging means32. The first arm31functions to support the first holding portion30. The first swinging means32functions to horizontally swing the first arm31. That is, one end of the first arm31is connected to the first holding portion30, and the other end of the first arm31is connected to the first swinging means32. Accordingly, when the first swinging means32is operated, the first arm31is horizontally rotated about the first swinging means32, i.e., about a vertical axis parallel to the Z direction, so that the first holding portion30can be moved between the standby area A and the grinding area B. Further, the loading means3includes first horizontal moving means33having a rail extending in the Y direction between the standby area A and the grinding area B. The first, horizontal moving means33functions to horizontally move the first swinging means32in the Y direction. Accordingly, when the first swinging means32is horizontally moved in the Y direction by the first horizontal moving means33, the first holding portion30can be horizontally moved In the Y direction.

The unloading means4is similar in configuration to the loading means3. That is, the unloading means4includes a second holding portion40for holding the wafer W (wafer W2), a second arm41for supporting the second holding portion40, second swinging means42for horizontally swinging the second arm41, and second horizontal moving means43for horizontally moving the second swinging means42in the Y direction. Accordingly, when the second swinging means42is horizontally moved in the Y direction by the second horizontal moving means43, the second holding portion40connected through the second arm41to the second swinging means42can be horizontally moved in the Y direction. The first holding portion30has a lower surface functioning as a holding surface for holding the wafer W (wafer W1) before grinding. Similarly, the second holding portion40has a lower surface functioning as a holding surface for holding the wafer W (wafer W2) after grinding. In particular, the holding surface of the second holding portion40is denoted by reference symbol40aas depicted inFIG. 2B.

There are provided in the grinding area B three disk-shaped chuck tables2each for holding the wafer W and a disk-shaped turn table6for supporting these three disk-shaped chuck tables2. The three chuck tables2have the same configuration. The three chuck tables2are provided on the turn table6so as to be arranged at equal intervals (at 120 degrees intervals) along the outer circumference of the turn table6. Each chuck table2is rotatable by any rotating means (not depicted) about a vertical axis parallel to the Z direction, and this vertical axis passes through the center of the chuck table2. Similarly, the turn table6is rotatable by any rotating means (not depicted) about a vertical axis parallel to the Z direction, and this vertical axis passes through the center oi the turn table6. Accordingly, when the turn table6is rotated, the three chuck tables2are rotated together about the center of the turn table6.

Each chuck table2is connected to suction means (not depicted) for applying a suction force to the chuck table2. Each chuck table2has an upper surface functioning as a holding surface20afor holding the wafer W under suction. Accordingly, when the suction means is operated, the suction force produced from the suction means is applied to the holding surface20aof each chuck table2, thereby holding the wafer W on the holding surface20aunder suction.

The first grinding unit7and the second grinding unit8for grinding the wafer W held on each chuck table2are provided in the grinding area3at its rear portion (in the +Y direction). The first grinding unit7includes a first grinding wheel71having a plurality of first abrasive members (not depicted) fixed at the lower end and arranged annularly along the outer circumference. The first grinding wheel71is rotatable about its vertical axis by any rotating means (not depicted). Further, the first grinding unit7includes a first elevating motor72for vertically moving the first grinding wheel71in the Z direction. Accordingly, when the first elevating motor72is operated, the first grinding wheel71can be vertically moved in the Z direction.

The second grinding unit8is similar in configuration to the first grinding unit7. That is, the second grinding unit8includes a second grinding wheel81having a plurality of second abrasive members (not depicted) and further includes a second elevating motor82for vertically moving the second grinding wheel81in the Z direction. The second grinding wheel81is also rotatable about its vertical axis by any rotating means (not depicted), and the second abrasive members are fixed at the lower end of the second grinding wheel81so as to be arranged annularly along the outer circumference of the second grinding wheel81. When the second elevating motor82is operated, the second grinding wheel81can be vertically moved in the Z direction.

Each second abrasive member in the second grinding unit8contains abrasive grains smaller in size than those contained in each first abrasive member in the first grinding unit7. For example, the first grinding unit7having the first abrasive members containing relatively large-sized abrasive grains is used to perform coarse grinding for reducing a thickness of the wafer W, and the second grinding unit8having the second abrasive members containing abrasive grains smaller in size than those of the first abrasive members is used to perform finish grinding for smoothening the upper surface Wa of the wafer W after performing the above coarse grinding by the first grinding unit7. However, the grinding unit in the grinding apparatus according to the present invention is not limited to the above configuration, but a single grinding unit may be provided in the grinding apparatus1.

A cleaning unit5is further provided in the grinding area B. The cleaning unit5includes a cleaning portion50for cleaning the holding surface20aof each chuck table2or the upper surface Wa of the wafer W (wafer W2) held on the holding surface20aand also includes third horizontal moving means51for horizontally moving the cleaning portion50in the X direction as the lateral direction of the grinding apparatus1. The cleaning portion50includes an abrasive cleaning portion500having cleaning abrasive members for cleaning and a two-fluid cleaning portion501for spraying a two-component fluid composed of cleaning water and air.

A first lower surface cleaning unit9A for cleaning the lower surface Wb of the wafer W (wafer W1) held by the first holding portion30is provided on the path of movement of the loading means3in the grinding area8. As depicted inFIG. 1, the first lower surface cleaning unit9A includes three cleaning members94and three cleaning water nozzles92for respectively supplying a cleaning water to these three cleaning members94. The three cleaning members94extend radially so as to be arranged at equal intervals (at 120 degrees intervals), and the three cleaning water nozzles92also extend radially so as to be arranged at equal intervals (at 120 degrees intervals). Each cleaning water nozzle92has a plurality of nozzle holes92afor spraying the cleaning water.

Similarly, a second lower surface cleaning unit9B for cleaning the lower surface Wb of the wafer W (wafer W2) held by the second holding portion40is provided on the path of movement of the unloading means4in the grinding area B. The second lower surface cleaning unit9B is similar in configuration to the first lower surface cleaning unit9A. In the second lower surface cleaning unit9B, the same parts as those of the first lower surface cleaning unit9A are denoted by the same reference symbols, and the description thereof will be omitted herein.

In addition, the second lower surface cleaning unit9B is provided with a holding surface cleaning portion90for cleaning the holding surface40aof the second holding portion40. For example, the holding surface cleaning portion90may be configured by a brush in the form of tightly set bristles of chemical fiber, vegetable fiber, etc. or a stone formed from resin bonded abrasive, resin material, etc. The holding surface cleaning portion90is adapted to come into abutment against the holding surface40aof the second holding portion40, thereby cleaning the holding surface40a.

The holding surface cleaning portion90and the cleaning members94are vertically movable. The vertical position of the holding surface cleaning portion SO is different from the vertical position of the cleaning members94, and the relation in vertical position between the holding surface cleaning portion90and the cleaning members94can be inverted. More specifically, in cleaning the lower surface Wb of the wafer W by using the cleaning members94, the cleaning members94are raised to a vertical position higher than that of the holding surface cleaning portion90. Conversely, in cleaning the holding surface40aof the second holding portion40by using the holding surface cleaning portion90, the holding surface cleaning portion90is raised and the cleaning members94are lowered, so that the vertical position of the holding surface cleaning portion90becomes higher than the vertical position of the cleaning members94.

2. Operation of Grinding Apparatus

There will now be described the operation of the grinding apparatus1in grinding the wafer W by using the grinding apparatus1.

First, the wafer W1stored in the first cassette15depicted inFIG. 1is drawn out by the robot12and then placed on the temporary setting table13by the robot12. During or before this operation, the third horizontal moving means51is operated to move the abrasive cleaning portion500and the two-fluid cleaning portion501In the X direction to the position above one of the three chuck tables2as depicted inFIGS. 2A and 2B, and the chuck table2is previously set at a standby position depicted inFIG. 2A. At this time, the two-fluid cleaning portion501is positioned near the center of the holding surface20aof the chuck table2. In this condition, the two-component fluid composed of water and air is sprayed from the two-fluid cleaning portion501, thereby cleaning the holding surface20aof the chuck table2.

Thereafter, the third horizontal moving means53is operated again to move the abrasive cleaning portion500and the two-fluid cleaning portion501in the +X direction as depicted inFIGS. 3A and 3B, thereby positioning the abrasive cleaning portion500near the center of the holding surface20aof the chuck table2. Thereafter, the chuck table2is rotated and the abrasive cleaning portion500is lowered until the cleaning abrasive members of the abrasive cleaning portion500come into contact with the holding surface20aof the chuck table2, thereby cleaning the holding surface20aof the chuck table2. As a modification, the two-fluid cleaning for cleaning the holding surface20aby using the two-fluid cleaning portion501as depicted inFIGS. 2A and 2Bmay be performed after performing the abrasive cleaning for cleaning the holding surface20aby using the abrasive cleaning portion500as depicted inFIGS. 3A and 3B.

Thereafter, as depicted inFIGS. 4A and 4B, the third horizontal moving means51is operated again to move the cleaning portion50toward the second holding portion40in the +X direction (the second direction defined in the present invention). Thereafter, the first horizontal moving means33is operated to move the first swinging means32in the direction, and the first swinging means32is next operated to swing the first arm31, thereby transferring the wafer Wi held by the first holding portion30from the temporary setting table13to the holding surface20aof the chuck table2. That is, the cleaning portion50is previously moved (retracted) from the chuck table2toward the second holding portion40in the +X direction (the second direction), so that the wafer W1can be loaded to the holding surface20aof the chuck table2by using the loading means3.

Thereafter, as depicted inFIGS. 5A and 5B, the third horizontal moving means51is operated to move the cleaning portion50in the −X direction to the position above the holding surface20aof the chuck table2on which the wafer W1is held. Thereafter, the turn table6is rotated 120 degrees in the clockwise direction as viewed in plan, so that the wafer W2ground by the second grinding unit8(seeFIG. 1) is moved to the position near the standby area A as depicted inFIG. 5A. That is, another chuck table2holding the wafer W2is moved from the grinding position below the second grinding unit8to the unloading position depicted inFIG. 5A. At the same time, the chuck table2holding the wafer W1is moved from the loading position depicted inFIG. 4Ato the position below the first grinding unit7(seeFIG. 1). Thereafter, the two-component fluid is sprayed from the two-fluid cleaning portion501to the upper surface Ha of the wafer W2ground, thereby cleaning the upper surface Wa of the wafer W2. Thereafter, the cleaning abrasive members of the abrasive cleaning portion500are brought into contact with the upper surface Wa of the wafer W2to thereby clean the upper surface Wa of the wafer W2.

Thereafter, as depicted inFIGS. 6A and 6B, the third horizontal moving means51is operated again to move the cleaning portion50toward the first holding portion30in the −X direction (the first direction defined in the present invention). Thereafter, the wafer W2is held by the second holding portion40and then unloaded from the chuck table2by the second holding portion40. That is, the cleaning portion50is previously moved (retracted) from the chuck table2toward the first holding portion30in the −X direction (the first direction), so that the wafer W2can be unleaded from the holding surface20aof the chuck table2by using the unloading means4.

As described above, the cleaning portion50is horizontally moved in the X direction by operating the third horizontal moving means51, so that the path of movement of the loading means3and the path of movement of the unloading means4can be ensured. Accordingly, it is unnecessary to vertically move the first holding portion30and the second holding portion40in the Z direction. As a result, the waiting time required for the grinding apparatus1in the case of vertically moving the first holding portion30and the second holding portion40can be eliminated to thereby reduce the total operation time for grinding.

After holding the wafer W2by using the second holding portion40of the unloading means4and then unloading the wafer W2from the chuck table2, the second holding portion40is moved to the spinner14by using the second swinging means42and the second horizontal moving means43as depicted inFIGS. 7A and 7B. Thus, the wafer W2is held on the upper surface of the spinner14, and the spinner14is next rotated to clean the wafer W2. At the same time, the cleaning portion50is moved in the +X direction to the position above the chuck table2by operating the third horizontal moving means51to clean the holding surface20aof the chuck table2. Thus, the cleaning of the wafer W2by the spinner14and the cleaning of the holding surface20aof the chuck table2by the cleaning portion50can be simultaneously performed.

As described above, the cleaning portion50is horizontally moved in the X direction by operating the third horizontal moving means51to thereby avoid the interference of the first holding portion30(or the second holding portion40) and the cleaning portion50. That is, it is possible to prevent that the cleaning portion50may collide with the first holding portion30(or the second holding portion40). In the past, the cleaning portion50has been provides with a receptacle for receiving a cleaning water or waste liquid from the cleaning portion50to thereby prevent water splashes to the loading means3(or the unloading means4). Meanwhile, according to the present invention, there is no timing of overlapping between the first holding portion30(or the second holding portion40) and the cleaning portion50as viewed in plan. Accordingly, the receptacle for the cleaning portion50can be eliminated. As a result, a cost for the receptacle itself can be eliminated and the time required for treatment of the waste liquid stored in the receptacle can also be eliminated.

Further, the grinding apparatus1further includes the first lower surface cleaning unit9A for cleaning the lower surface Wb of the wafer W1held by the first holding portion30. Accordingly, as depicted inFIGS. 8A and 8B, the lower surface Wb of the wafer W1can be cleaned by the first lower surface cleaning unit9A before moving the wafer W1from the temporary setting table13to the chuck table2. That is, the first lower surface cleaning unit9A is located on the path of movement of the wafer W1by the loading means3. Accordingly, before placing the wafer W1on the holding surface20aof the chuck table2, the wafer W1held by the first holding portion30is positioned above the first lower surface cleaning unit9A to thereby clean the lower surface Wb of the wafer W1. More specifically, a cleaning water is sprayed from the nozzle holes92aof each cleaning water nozzle92in the first lower surface cleaning unit9A and thereby supplied to the lower surface Wb of the wafer W1held by the first holding portion30. At the same time, each cleaning member94in the first lower surface cleaning unit94is brought into contact with the lower surface Wb of the wafer W1as being rotated about a rotating shaft90aby operating any rotating means (not depicted). Thus, the lower surface Wb of the wafer W1can be cleaned by the first lower surface cleaning unit9A. During this cleaning operation by the first lower surface cleaning unit9A, the wafer W2ground can be unloaded from the holding surface20aof the chuck table2by using the unloading means4. Accordingly, the time required for loading of the wafer W1to the holding surface20aand the time required for unloading of the wafer W2from the holding surface20acan be reduced to thereby improve the operation efficiency in grinding.

Similarly, the grinding apparatus1further includes the second lower surface cleaning unit9B for cleaning the lower surface Wb of the wafer W2held by the second holding portion40. Accordingly, as depicted inFIGS. 9A and 9B, the lower surface Wb of the wafer W2can be cleaned by the second lower surface cleaning unit9B before moving the wafer W2from the chuck table2to the spinner14. That is, the second lower surface cleaning unit9B is located on the path of movement of the wafer W2by the unloading means4. Accordingly, before placing the wafer W2on the upper surface of the spinner14, the wafer W2held by the second holding portion40is positioned above the second lower surface cleaning unit9B to thereby clean the lower surface Wb of the wafer W2. The cleaning operation by the second lower surface cleaning unit9B is similar to that by the first lower surface cleaning unit9A. During this cleaning operation by the second lower surface cleaning unit9B, another wafer W1can be loaded to the holding surface20aof the chuck table2by using the loading means3. Accordingly, the operation efficiency can be further improved.

In addition, the second lower surface cleaning unit9B includes the holding surface cleaning portion90having resin bonded abrasive or the like for cleaning the holding surface40aof the second holding portion40. Accordingly, in the condition where the wafer W2is not held by the second holding portion40, the resin bonded abrasive of the holding surface cleaning portion90is brought into contact with the holding surface40aof the second holding portion40as supplying a cleaning water from the cleaning water nozzles92, thereby cleaning the holding surface40aof the second holding portion40. By cleaning the holding surface40ato keep the condition that no foreign matter adheres to the holding surface40a,there is no possibility that foreign matter may be caught between the holding surface40aand the upper surface Wa of the wafer W2. Accordingly, there is no possibility of scratches on the upper surface Wa of the wafer W2(the surface to be held on the holding surface40a) due to the foreign matter. Further, it is possible to prevent that the wafer W2held on the holding surface40amay be damaged by the foreign matter.