Apparatus and method for polishing objects using object cleaners

An apparatus and method for polishing objects, such as semiconductor wafers, uses at least one object cleaner, which may be a movable object cleaner. The movable object cleaner allows access to different parts of the apparatus for maintenance.

FIELD OF THE INVENTION

The invention relates generally to semiconductor processing equipments, and more particularly to an apparatus and method for polishing semiconductor wafers.

BACKGROUND OF THE INVENTION

Local and global planarization of semiconductor wafers becomes increasingly important as more metal layers and interlayer dielectric layers are stacked on the wafers. A preferred method to planarize semiconductor wafers is the chemical mechanical polishing (CMP) method, where a surface of a semiconductor wafer is polished using a slurry solution supplied between the wafer and a polishing pad. The CMP method is also widely used for damascene process to form copper structures on the semiconductor wafers.

In general, a CMP equipment includes a polishing table where a polishing pad is placed and a wafer carrier that supports a semiconductor wafer and presses the wafer against the polishing pad. The CMP equipment may also include a wafer cleaner to clean and dry the polished wafers.

One of the most important considerations of a CMP equipment is productivity. For higher productivity, a CMP equipment typically requires more polishing tables and more wafer carriers. As the number of polishing tables and wafer carriers included in a CMP equipment is increased, the arrangement of the polishing tables and the wafer carriers becomes important to efficiently polish multiple semiconductor wafers. Furthermore, the manner in which the semiconductor wafers are transferred to and from the wafer carrier and the wafer cleaner becomes important as well. However, the footprint of a CMP equipment must also be considered since a CMP equipment with a large footprint requires a larger clean room to house the equipment, which translates into greater cost of operation.

In view of these issues, what is needed is an apparatus and method for polishing semiconductor wafer with high productivity, which does not require a large footprint.

SUMMARY OF THE INVENTION

An apparatus and method for polishing objects, such as semiconductor wafers, uses at least one object cleaner, which may be a movable object cleaner. The movable object cleaner allows access to different parts of the apparatus for maintenance. The movable object cleaner also allows the apparatus to have a smaller footprint. The apparatus may include a polishing station that comprises multiple polishing units to increase the productivity of the apparatus.

An apparatus for polishing objects in accordance with an embodiment of the invention comprises a polishing station, a movable object cleaner, an object transport device and a guide mechanism. The polishing station includes at least one polishing unit to polish the objects. The movable object cleaner is positioned adjacent to a side of the polishing station. The movable object cleaner includes a cleaning station and a drying station. The object transport device is positioned to transfer the objects from the polishing station to the movable object cleaner. The guide mechanism is operatively connected to the polishing station and the movable object cleaner. The guide mechanism is configured to allow the movable object cleaner to be displaced from an initial position to a subsequent position to provide access to parts of the polishing station. The guide mechanism is further configured to allow the movable object cleaner to be displaced back to the initial position from the subsequent position.

An apparatus for polishing objects in accordance with an embodiment of the invention comprises a polishing station, a movable object cleaner, an object transport device and a guide mechanism. The polishing station includes a plurality of polishing units to polish the objects and at least one object relay device to transfer the objects between the polishing units. The polishing station is rectangular in shape with two longer sides and two shorter sides. The movable object cleaner is positioned adjacent to one of the two longer sides of the polishing station. The movable object cleaner includes a cleaning station and a drying station. The object transport device is positioned to transfer the objects from the polishing station to the movable object cleaner. The guide mechanism is operatively connected to the polishing station and the movable object cleaner. The guide mechanism is configured to allow the movable object cleaner to be displaced from an operational position to a maintenance position to provide access to parts of the polishing station. The guide mechanism is further configured to allow the movable object cleaner to be displaced back to the operational position from the maintenance position.

An apparatus for polishing objects in accordance with another embodiment of the invention comprises a polishing station, first and second object cleaners and at least one object transport device. The polishing station comprises first and second polishing units and first and second object relay devices. Each of the first and second polishing units includes a polishing table and first and second object carriers. The first and second object relay devices are positioned between the first polishing unit and the second polishing unit. The first object relay device is positioned to transfer a first object from the first object carrier of the first polishing unit to the first object carrier of the second polishing unit along an original direction. The second object relay device is positioned to transfer a second object from the second object carrier of the first polishing unit to the second object carrier of the second polishing unit along the original direction. The first and second object cleaners are positioned near the polishing station. Each of the first and second object cleaners includes a cleaning station and a drying station. The first object cleaner is configured to process the first object at the cleaning station and the drying station of the first object cleaner such that the first object is transferred along a return direction within the first object cleaner. The second object cleaner is configured to process the second object at the cleaning station and the drying station of the second object cleaner such that the second object is transferred along the return direction within the second object cleaner. The return direction is the opposite direction of the original direction. The at least one object transport device is positioned to transfer the first object from the polishing station to the first object cleaner and to transfer the second object from the polishing station to the second object cleaner.

A method of polishing objects in accordance with an embodiment of the invention comprises transferring a first object from a first object carrier of a first polishing unit to a first object relay device and from the first object relay device to a first object carrier of a second polishing unit along an original direction within a polishing station, including polishing the first object at the first and second polishing units, transferring a second object from a second object carrier of the first polishing unit to a second object relay device and from the second object relay device to a second object carrier of the second polishing unit along the original direction within the polishing station, including polishing the second object at the first and second polishing units, transferring the first object from the polishing station to a first object cleaner and the second object from the polishing station to a second object cleaner, each of the first and second object cleaners including a cleaning station and a drying station, processing the first object at the cleaning station and the drying station of the first object cleaner such that the first object is transferred along a return direction within the first object cleaner, the return direction being the opposite direction of the original direction, and processing the second object at the cleaning station and the drying station of the second object cleaner such that the second object is transferred along the return direction within the second object cleaner.

DETAILED DESCRIPTION

With reference toFIGS. 1,2and3, a polishing apparatus10in accordance with an embodiment of the present invention is described.FIG. 1is a top view of the polishing apparatus10.FIGS. 2 and 3are side views of components of a polishing station20of the polishing apparatus10. The polishing apparatus10comprises the polishing station20, a wafer storage station102, a first wafer transport device150, a second wafer transport device210, a third wafer transport device210′, a first movable wafer cleaner220and a second movable wafer cleaner220′.

The polishing station20is an enclosed structure with window-like mechanisms (not shown) that can be opened to transfer semiconductor wafers into and out of the polishing station20. As shown inFIG. 1, the polishing station20in this embodiment is rectangular in shape with two longer sides20L and20L′ and two shorter sides. The polishing station20comprises a first polishing unit250a, a second polishing unit250b, first two wafer relay devices280aand280a′, second two wafer relay devices280band280b′, and third two wafer relay devices280cand280c′.

Each polishing unit250of the polishing station20comprises a polishing table256, a first wafer carrier assembly260and a second wafer carrier assembly260′. The polishing table256can be rotated or orbited about an axis. A polishing pad255may be attached onto the polishing table256for chemical and mechanical polishing process of semiconductor wafers. One or more slurries containing abrasive particles and/or chemicals such as KOH are used with the polishing pad255to polish semiconductor wafers. Each polishing unit250may further comprises a pad conditioner258to condition the surface of the polishing pad255during the polishing process to refresh the surface of the polishing pad255for proper polishing. Although the polishing processes of wafers are described herein as being performed on one or more polishing pad surfaces, the wafer polishing processes may be performed on any polishing surface such as a polishing surface of a polishing table. The area of the polishing station20is an area roughly defined by the polishing tables256aand256bof the polishing station20.

Each wafer carrier assembly260of the polishing units250aand250bcomprises a wafer carrier262, a carrier shaft264and a rotational-and-vertical drive mechanism266, as illustrated inFIGS. 2 and 3. The wafer carrier262is designed to hold a semiconductor wafer such that the surface of the wafer to be polished is faced toward the polishing pad255. The wafer carrier262is connected to the rotational-and-vertical drive mechanism266through the carrier shaft264. The rotational-and-vertical drive mechanism266controls the rotational and vertical motions of the wafer carrier262through the connected carrier shaft264. Thus, the rotational- and vertical drive mechanism266is configured to rotate the wafer carrier262by rotating the connected carrier shaft264and to vertically move the wafer carrier262by vertically moving the connected carrier shaft264. In order to polish semiconductor wafers, the wafer carriers262are moved down to the respective polishing pads255by the respective rotating-and-vertical mechanisms266to press the wafers held by the wafer carriers262onto the respective polishing pads255.

The wafer relay devices280of the polishing station20accommodate wafers transferred to and from the wafer relay devices280. Each wafer relay device280includes a load-and-unload cup (commonly known in the semiconductor industry as a load cup) to receive or unload a wafer released from a wafer carrier and to place or load a wafer onto a wafer carrier. The wafer relay devices280and the two polishing units250are arranged in such a manner that the first two wafer relay devices280aand280a′ are positioned in front of the first polishing unit250a, the second two wafer relay devices280band280b′ are positioned between the first polishing unit250aand the second polishing unit250b, and the third two wafer relay devices280cand280c′ are positioned behind the second polishing unit250c, as illustrated inFIG. 1. Positions of the wafer relay devices280inFIG. 1are their respective parking positions.

The wafer cleaners220and220′ are enclosed structures with window-like like mechanisms (not shown) that can be opened to transfer semiconductor wafers into and out of the wafer cleaners. The first wafer cleaner220comprises a wafer receiving station222, a first cleaning station224, a second cleaning station226, a drying station228, a first wafer transport device232, a second wafer transport device234and a third wafer transport device236. The wafer receiving station222accommodates wafers that are transferred by the second wafer transport device210. The first wafer transport device232transfers wafers from the wafer receiving station222to the first cleaning station224. The second wafer transport device234transfers wafers from the first cleaning station224to the second cleaning station226. The third wafer transport device236transfers wafers from the second cleaning station226to the drying station228. Dried wafers are removed from the drying station228by the first wafer transport device150and then transferred to the wafer storage station102.

The first and second cleaning stations224and226of the wafer cleaner220remove slurry particles from wafer surfaces using D.I. water and/or chemicals, such as NH4OH, diluted HF and organic chemicals. The wafer receiving station222can be also configured to remove slurry particles from wafer surfaces using D.I. water and/or chemicals, such as NH4OH, diluted HF and organic chemicals. After the cleaning process is completed at the second cleaning station226, wafers are rinsed with D.I. water and then dried in the drying station228.

The wafer cleaner220may comprise more than two cleaning stations or may comprise a single cleaning station. In this embodiment, the second wafer cleaner220′ is identical to the first wafer cleaner220. As shown inFIG. 1, each of the wafer cleaners220and220′ in this embodiment is rectangular in shape with two longer sides and two shorter sides. In order to minimize the width of the polishing apparatus10, the wafer cleaners220and220′ are positioned such that their respective longer sides220L and220L′ are facing the longer sides20L and20L′ of the polishing station20, respectively, as illustrated inFIG. 1. The wafer cleaner220is positioned adjacent to the polishing station20such that the longer side220L of the wafer cleaner220is facing the longer side20L of the polishing station20. The longer side220L of the wafer cleaner220facing the polishing station20may or may not be in contact with the longer side20L of the polishing station. Similarly, the wafer cleaner220′ is positioned adjacent to the polishing station20such that the longer side220L′ of the wafer cleaner220′ is facing the longer side20L′ of the polishing station20. The longer side220L′ of the wafer cleaner220′ facing the polishing station20may or may not be in contact with the longer side20L′ of the polishing station.

The wafer storage station102accommodates semiconductor wafers or other comparable objects to be polished by the polishing station20. The wafer storage station102can also accommodate semiconductor wafers or other comparable objects that have been polished and cleaned by the polishing station20and the wafer cleaners220and220′.

The first wafer transport device150transfers wafers from the wafer storage station102to the polishing station20. More specifically, the first wafer transport device150transfers wafers from the wafer storage station102to the first wafer relay devices280aand280a′ of the polishing station20. The second wafer transport device210transfers wafers from the polishing station20to the first wafer cleaner220. More specifically, the second wafer transport device210transfers wafers from the third wafer relay device280cof the polishing station20to the wafer receiving station222of the first wafer cleaner220. The third wafer transport device210′ transfers wafers from the polishing station20to the wafer second cleaner220′. More specifically, the third wafer transport device210′ transfers wafers from the third wafer relay device280c′ of the polishing station20to the wafer receiving station222′ of the second wafer cleaner220′. The first wafer transport device150also transfers wafers from the first and second wafer cleaners220and220′ to the wafer storage station102. More specifically, the first wafer transport device150transfers wafers from the drying stations228and228′ of the first and second wafer cleaners220and220′ to the wafer storage station102.

The first, second and third wafer transport devices150,210and210′ may be situated on respective linear tracks155,215and215′ such that the wafer transport devices can be moved in a linear manner on the linear tracks by respective linear drive mechanisms (not shown). As an example, the first, second and third wafer transport devices150,210and210′ may comprise a robotic arm to handle a wafer for transfer. The first wafer transport device150may be configured to comprise dual robotic arms150aand150b, as illustrated inFIG. 1, such that each robotic arm150aor150bcan handle wafers individually. The first, second and third wafer transport devices150,210and210′ may also be configured to turn over wafers before transferring the wafers to the polishing station20, the wafer cleaner220or the wafer cleaner220′.

In an embodiment of the present invention, the polishing apparatus10further comprises a buffer station105. The buffer station105accommodates wafers to be polished by the polishing station20. In this embodiment, the first robotic arm150aof the first wafer transport device150transfers wafers from the wafer storage station102to the buffer station105and the second robotic arm150bof the first wafer transport device150transfers wafers from the buffer station105to the polishing station20. Cleaned wafers at the wafer cleaners220and220′ are transferred from the wafer cleaners only by the first robotic arm150aof the first wafer transport device150. The first robotic arm150a, which is used to transfer clean wafers between the storage station102, the buffer station105and the wafer cleaners220and220′, does not enter the polishing station20which is contaminated by slurry.

In an alternative configuration, the polishing apparatus10ofFIG. 1can be modified such that the second wafer transport device210transfers wafers from the polishing station20to both the first and second wafer cleaners220and220′. In this alternative configuration, the linear track215is positioned next to the polishing station20near the wafer relay devices280cand280c′ such that the wafer transport device210can reach both the wafer receiving stations222and222′ of the wafer cleaners220and220′, respectively, as well as the wafer relay devices280cand280c′. In operation, the second wafer transport device210transfer wafers from the wafer relay devices280cand280c′ of the polishing station20to the wafer receiving stations222and222′ of first and second wafer cleaners220and220′, respectively. Thus, in this alternative configuration, the third wafer transport device210′ is not needed, and thus, is removed from the polishing apparatus10.

With reference toFIGS. 1 and 2, a method of processing wafers in the polishing apparatus10according to an embodiment of the present invention is described. In this embodiment, the wafer relay devices280of the polishing station20are connected to ancillary devices (not shown), which move the wafer relay devices linearly in order to deliver wafers to their next destinations. Details of how to move the wafer relay devices280linearly and the ancillary devices that are used to move the wafer relay devices280have been described with reference to FIGS. 9-17 of U.S. patent application Ser. No. 10/829,593, filed on Apr. 21, 2004, which is incorporated herein by reference.

First, the first wafer relay devices280aand280a′ (1) receive wafers at their respective parking positions, as shown inFIG. 1, from the first wafer transport device150, (2) move linearly to the wafer carriers262aand262a′ of the first polishing unit250a, respectively, (3) transfer the wafers to the wafer carriers262aand262a′ over the polishing table256a, respectively, and then (4) return to their respective parking positions.

Next, the wafer carriers262aand262a′ move down to the polishing pad255aof the polishing table256aand then polish the wafers.

Next, after the wafers are polished on the polishing pad255a, the wafer carriers262aand262a′ are lifted from the polishing pad255a.

Next, the second wafer relay devices280band280b′ (1) move linearly to the wafer carriers262aand262a′ of the first polishing unit250a, respectively, from their respective parking positions, as shown inFIG. 1, (2) receive the wafers from the wafer carriers262aand262a′ over the polishing table256a, (3) move linearly to the wafer carriers262band262b′ of the second polishing unit250b, respectively, (4) transfer the wafers to the wafer carriers262band262b′ over the polishing table256b, respectively, and then (5) return to their respective parking positions.

Next, the wafer carriers262band262b′ move down to the polishing pad255bof the polishing table256band then polish the wafers.

Next, after the wafers are polished on the polishing pad255b, the wafer carriers262band262b′ are lifted from the polishing pad255b.

Next, the third wafer relay devices280cand280c′ (1) move linearly to the wafer carriers262band262b′ of the second polishing unit250b, respectively, from their respective parking positions, as shown inFIG. 1, (2) receive the wafers from the wafer carriers262band262b′ over the polishing table256b, and then (4) return to their respective parking positions.

Next, the wafers are removed from the third wafer relay devices280cand280c′ by the second and third wafer transport devices210and210′, respectively, and then transferred to the first and second wafer cleaners220and220′, respectively. In the alternative configuration of the polishing apparatus without the third wafer transport device210′, the second wafer transport device210removes the wafers from the third wafer relay devices280cand280c′ and then transfer the wafers to the first and second wafer cleaners220and220′.

With reference toFIGS. 1 and 3, a method of processing wafers in the polishing apparatus10according to another embodiment of the present invention is described. In this embodiment, the wafer carrier assemblies260are connected to ancillary devices, which move the wafer carrier assemblies linearly in order to deliver wafers to their next destinations. Details of how to move the wafer carrier assemblies260linearly and the ancillary devices that are used to move the carrier assemblies260linearly have been described with reference to FIGS. 18-28 of U.S. patent application Ser. No. 10/829,593, filed on Apr. 21, 2004, which is incorporated herein by reference.

First, the first wafer relay devices280aand280a′ receive wafers at their respective parking positions from the first wafer transport device150.

Next, the wafer carrier assemblies260aand260a′ of the first polishing unit250a(1) move linearly to the wafer relay devices280aand280a′, respectively, from their initial positions over the polishing table256a, (2) receive the wafers from the wafer relay devices280aand280a′ at their respective parking positions, and then (3) return to the polishing table256aof the first polishing unit250a.

Next, the wafer carriers262aand262a′ move down to the polishing pad255aof the polishing table256aand then polish the wafers.

Next, after the wafers are polished on the polishing pad255a, the wafer carriers262aand262a′ are lifted from the polishing pad255a.

Next, the wafer carrier assemblies260aand260a′ of the first polishing unit250a(1) move linearly to the wafer relay devices280band280b′, respectively, (2) transfer the wafers to the wafer relay devices280band280b′ at their respective parking positions, and then (3) return to the polishing table256aof the first polishing unit250a.

Next, the wafer carrier assemblies260band260b′ of the second polishing unit250b(1) move linearly to the wafer relay devices280band280b′, respectively, from their initial positions over the polishing table256b, (2) receive the wafers from the wafer relay devices280band280b′ at their respective parking positions, and then (3) return to the polishing table256bof the second polishing unit250b.

Next, the wafer carriers262band262b′ move down to the polishing pad255bof the polishing table256band then polish the wafers.

Next, after the wafers are polished on the polishing pad255b, the wafer carriers262band262b′ are lifted from the polishing pad255b.

Next, the wafer carrier assemblies260band260b′ of the second polishing unit250b(1) move linearly to the wafer relay devices280cand280c′, respectively, (2) transfer the wafers to the wafer relay devices280cand280c′ at their respective parking positions, and then (3) return to the polishing table256bof the second polishing unit250b.

Next, the wafers are removed from the third wafer relay devices280cand280c′ by the second and third wafer transport devices210and210′, respectively, and then transferred to the wafer cleaners220and220′, respectively. In the alternative configuration of the polishing apparatus10without the third wafer transport device210′, the second wafer transport device210removes the wafers from the third wafer relay devices280cand280c′ and then transfer the wafers to the first and second wafer cleaners220and220′.

In an alternative embodiment of the present invention, the first two wafer relay devices280aand280a′ of the polishing station20in the polishing apparatus10ofFIG. 1can be removed. In this embodiment, the first wafer transport device150transfers wafers directly to the wafer carriers262aand262a′ of the first polishing unit250a.

In another alternative embodiment of the present invention, the third two wafer relay devices280cand280c′ of the polishing station20in the polishing apparatus10ofFIG. 1can be removed. In this embodiment, the second and third wafer transport devices210and210′ transfer wafers directly from the wafer carriers262band262b′ of the second polishing unit250bto the first and second wafer cleaners220and220′, respectively. In the alternative configuration of the polishing apparatus10without the third wafer transport device210′, the second wafer transport device210transfers wafers directly from the wafer carriers262band262b′ of the second polishing unit250bto the first and second wafer cleaners220and220′.

In another alternative embodiment of the present invention, the first wafer relay devices280aand280a′ and the third wafer relay devices280cand280c′ of the polishing station20in the polishing apparatus10ofFIG. 1can be removed. In this embodiment, the first wafer transport device150transfers wafers directly to the wafer carriers262aand262a′ of the first polishing unit250a. The second and third wafer transport devices210and210′ transfer wafers directly from the wafer carriers262band262b′ of the second polishing unit250bto the first and second wafer cleaners220and220′, respectively. In the alternative configuration of the polishing apparatus10without the third wafer transport device210′, the second wafer transport device210transfers wafers directly from the wafer carriers262band262b′ of the second polishing unit250bto the first and second wafer cleaners220and220′.

With the two wafer cleaners220and220′ integrated with the polishing stations20, higher throughput of the polishing apparatus10is achieved. In addition, positioning the wafer cleaners220and220′ such that they face the longer sides20L and20L′ of the polishing stations20minimizes the width of the polishing apparatus10. Therefore, more polishing apparatuses can be installed at smaller clean rooms. When users need to maintain the polishing stations20whose longer sides220L and220L′ are surrounded by the wafer cleaners220and220′, the wafer cleaners220and220′ can be moved such that the polishing stations20are exposed to the users in the following manners.

The configuration of the polishing apparatus10allows wafers to be transferred from the polishing station20to the wafer cleaners220and220′ efficiently. In the polishing station20, each wafer is transferred on one of two paths along an original direction. The original direction is a linear direction from the front of the polishing apparatus10, where the wafer storage station102is situated, to the back of the polishing apparatus, where the third wafer relay devices280cand280c′ are situated. The first wafer path in the polishing station20involves transferring wafers on the following sequence of elements: the first wafer relay device280a, the first wafer carrier262a, the second wafer relay device280b, the first wafer carrier262band the third wafer relay device280c. The second wafer path in the polishing station20involves transferring wafers on the following sequence of elements: the first wafer relay device280a′, the second wafer carrier262a′, the second wafer relay device280b′, the second wafer carrier262b′ and the third wafer relay device280c′. In the wafer cleaners220and220′, each wafer is transferred along a return direction, which is the opposite direction of the original direction.

With reference toFIGS. 1,4and5, an embodiment of the present invention in order to move the wafer cleaners220ad220′ is described.FIG. 1is a top view of the polishing apparatus10with the wafer cleaners220and220′ located at their respective operational positions.FIG. 4is a top view of the polishing apparatus10with the wafer cleaners220and220′ located at their respective maintenance positions.FIG. 5is a side view of the wafer cleaner220(at its maintenance position), a fluid conduit system290, the second wafer transport device210and the polishing station20, which are viewed from the direction X inFIG. 4.

The polishing apparatus10ofFIG. 1comprises linear guides230and230′ that are parallel to the longer sides20L and20L′ of the polishing station20. The wafer cleaners220and220′ are movably connected to the linear guides230and230′, respectively, and can be moved in a direction parallel to the longer sides20L and20L′ of the polishing station20along the respective linear guides, as illustrated inFIGS. 4 and 5. The second and third wafer transport devices210and210′ and the linear tracks215and215′ can be configured to move together with the wafer cleaners220and220′, respectively, as illustrated inFIG. 4, when the wafer cleaners220and220′ are moved. As an example, the linear tracks215and215′ may be attached to the wafer cleaners220and220′, respectively, by a suitable connecting structure216, as illustrated inFIG. 5.

Since the wafer cleaners220and220′ are identical in this embodiment, only the wafer cleaner220is described in detail. As illustrated inFIG. 5, the wafer cleaner220is mounted on multiple supports221such that the fluid conduit system290can be installed under the wafer cleaner220. The wafer cleaner220is also mounted on wheels222through the multiple supports221such that the wafer cleaners220can be rolled on the wheels222. Instead of the wheels222, other devices can be used that minimize friction of moving the wafer cleaner220across a floor (not shown) of a facility where the polishing apparatus10is installed.

When the first wafer cleaner220is moved in the direction A, as illustrated inFIG. 4, users can access the first and second wafer relay devices280aand280b, the wafer carrier assembly260aand the polishing table256aof the polishing station20in order to maintain them. However, when the first wafer cleaner220is moved in the direction B, as shown inFIG. 4with respect to the second wafer cleaner220′, the users can access the third wafer relay device280c, the wafer carrier assembly260band the polishing table256bof the polishing station20in order to maintain them.

Similarly, when the second wafer cleaner220′ is moved in the direction B, as illustrated inFIG. 4, the users can access the third wafer relay device280c′, the wafer carrier assembly260b′ and the polishing table256bof the polishing station20in order to maintain them. When the second wafer cleaner220′ is moved to the direction A, as shown inFIG. 4with respect to the first wafer cleaner220, the users can access the first and second wafer relay devices280a′ and280b′, the wafer carrier assembly260a′ and the polishing table256aof the polishing station20in order to maintain them.

The wafer cleaner220is connected to a bottom housing12of the polishing apparatus10through the fluid conduit system290, as illustrated inFIG. 5. Alternatively, instead of the bottom housing12, the fluid conduit system290can connect the wafer cleaner220directly to a floor (not shown) of a facility where the polishing apparatus10is installed.

The fluid conduit system290can be used as a housing for multiple fluid channels450that supply D.I. water and chemicals such as D.I. water and HF from their respective sources (not shown) to the wafer cleaner220and drain used D.I. water and chemicals from the wafer cleaner220to their respective drains (not shown), as illustrated inFIG. 5. The fluid conduit system290is configured to be bendable such that the wafer cleaner220can move back and forth in a linear manner with respect to the polishing station20without disconnecting the fluid conduit system290, as illustrated inFIGS. 1 and 4.

The fluid conduit system290comprises a first joint300, a second joint400, a floating joint350, a first tube325and a second tube375. The first joint300is mounted to the wafer cleaner220. The second joint400is mounted to the bottom housing12of the polishing apparatus10. Alternatively, the second joint400can be mounted to a floor of a facility where the polishing apparatus10is installed instead of the bottom housing12. A first end325aof the first tube325is connected to the first joint300such that the first tube325can pivot about the first joint300. A second end325bof the first tube325is connected to the floating joint350such that the first tube325can also pivot about the floating joint350.

A first end375aof the second tube375is connected to the second joint400such that the second tube375can pivot about the second joint400. A second end375bof the second tube375is connected to the floating joint350such that the second tube375can also pivot about the floating joint350. As illustrated inFIGS. 1 and 4, free movement of the floating joint350relative to the first and second joints300and400and the pivoting motions of the first and second tubes325and375make it possible to move the wafer cleaner220in the linear manner without disconnecting the fluid conduit system290.

Even though the fluid conduit system290is described to comprise one floating joint350and two tubes325and375connected to the floating joint350, it is also possible to use any type of fluid conduit systems which can connect the first joint300and the second joint400. Generally, fluid conduit systems that can be used in the polishing apparatus10comprise N floating joints and N+1 tubes, where N is an integer equal to or larger than2, such that n'th floating joint is connected to n'th and n+1'th tubes, where n is an integer equal to or smaller than N. The first tube connects the first joint300and the first floating joint of the N floating joints. The last tube connects the second joint400and the last floating joint of the N floating joints.

In an embodiment, the lengths of the first and second tubes325and375and the locations of the first and second joints300and400are selected such that the floating joint350does not protrude from under the first wafer cleaner220when the fluid conduit system290bends due to a linear movement of the wafer cleaner220.

According to an alternative embodiment of the present invention, the linear guides230and230′ of the polishing apparatus10can be replaced with linear guide mechanisms370and370′, which are illustrated inFIGS. 6,7and8, in order to move the wafer cleaners220and220′ to access components of the polishing station20.

FIG. 6is a top view of the polishing apparatus10comprising the linear guide mechanisms370and370′ with the wafer cleaners220and220′ located at their respective operational positions.FIG. 7is another top view of the polishing apparatus10comprising the linear guide mechanisms370and370′ with the wafer cleaners220and220′ located at their respective maintenance positions.FIG. 8is a side view of the wafer cleaners220and220′ (at their respective maintenance positions), the fluid conduit systems290and290′, and the polishing station20of the polishing apparatus10comprising the linear guide mechanisms370and370′, which are viewed from the direction Y inFIG. 7.

The polishing apparatus10ofFIG. 6is similar to the polishing apparatus10ofFIG. 1except that the wafer cleaners220and220′ are configured to move apart from the polishing station20in a linear manner using the linear guide mechanisms370and370′. The wafer cleaner220is configured to be moved in the direction C away from the polishing station20, as illustrated inFIGS. 7 and 8, using the two linear guide mechanisms370, which are each attached to the polishing station20and the wafer cleaner220. Thus, the space between the polishing station20and the wafer cleaner220is increased. Similarly, the wafer cleaner220′ is configured to be moved in the direction D away from the polishing station20, as illustrated inFIGS. 7 and 8, using the two linear guide mechanisms370′, which are each attached to polishing station20and the wafer cleaner220′. Thus, the space between the polishing station20and the wafer cleaner220′ is increased. The fluid conduit system290that was described with reference toFIGS. 1,4and5can be used in the polishing apparatus10ofFIG. 6.

In this embodiment, the linear guide mechanisms370and370′ are identical. Thus, only one of the linear guide mechanisms370and370′ is described in detail. The linear guide mechanism370comprises an elongate male portion380and an elongate female portion385. The female portion385is mounted to the polishing station20such that it receives the male portion380. A first end of the male portion380is connected to the wafer cleaner220and a second end of the male portion380is inserted in the female portion385. When the wafer cleaner220is moved apart from the polishing station20, the male portion380is pulled out from the female portion385, which extends the linear guide mechanism370, as illustrated inFIGS. 7 and 8. Thus, the linear guide mechanisms370and370′ are used to linearly move the wafer cleaners220and220′ to their respective predetermined positions.

Users can access the polishing units250and the wafer relay devices280of the polishing station20either from the space between the moved first wafer cleaner220and the longer side20L of the polishing station20or the space between the moved second wafer cleaner220′ and the longer side20L′ of the polishing station20in order to maintain the wafer relay devices280and the polishing units250, as illustrated inFIG. 7.

According to another alternative embodiment of the present invention, the linear guides230and230′ of the polishing apparatus10ofFIG. 1can be replaced with pivoting guide mechanisms500and500′, illustrated inFIGS. 9,10and11, in order to move the wafer cleaners220and220′ to access components of the polishing station20.

FIG. 9is a top view of the polishing apparatus10comprising the pivoting guide mechanisms500and500′ with the wafer cleaners220and220′ located at their respective operational positions.FIG. 10is a top view of the polishing apparatus10comprising the pivoting guide mechanisms500and500′ with the wafer cleaners220and220′ located at their respective maintenance positions.FIG. 11is a side view of the wafer cleaners220and220′ (at their respective maintenance positions), fluid conduit systems600and600′ (described below), and the polishing station20of the polishing apparatus10comprising the pivoting guide mechanisms500and500′, which are viewed from the direction Y inFIG. 10.

The polishing apparatus10ofFIG. 9is similar to the polishing apparatus10ofFIG. 1except that the wafer cleaners220and220′ are configured to move apart from the polishing station20in a pivoting manner using the pivoting guide mechanisms500and500′. The wafer cleaner220is configured to be pivoted in the direction E away from the polishing station20, as illustrated inFIGS. 10 and 11, using the two pivoting guide mechanisms500, which are each attached to polishing station20and the wafer cleaner220. Similarly, the wafer cleaner220′ is configured to be pivoted in the direction F away from the polishing station20, as illustrated inFIGS. 10 and 11, using the two pivoting guide mechanisms500′, which are each attached to polishing station20and the wafer cleaner220′.

In this embodiment, the pivoting guide mechanisms500and500′ are identical. Thus, only one of the pivoting guide mechanisms500and500′ is described in detail. The pivoting guide mechanism500comprises a first joint510, a second joint520and a shaft530. The first joint510is mounted to the polishing station20and the second joint520is mounted to the wafer cleaner220, as best shown inFIG. 11. A first end530aof the shaft530is connected to the first joint510such that the shaft530can pivot about the first joint510. A second end530bof the shaft530is connected to the second joint520such that the shaft530can pivot about the second joint520. As illustrated with the arrow E inFIG. 10, the shaft530pivots about the joints510and520when the wafer cleaner220is moved away from the polishing station20. The pivoting guide mechanism500′ operates in a similar fashion to move the wafer cleaner220′ apart from the polishing station20, as illustrated with the arrow F inFIG. 10. Thus, the pivoting guide mechanisms500and500′ are used to move the wafer cleaners220and220′ to their respective predetermined positions.

In the polishing apparatus10ofFIG. 9comprising the pivoting guide mechanisms500and500′, the fluid conduit systems600and600′ can be used instead of the fluid conduit systems290and290′, which were described above with reference toFIGS. 1,4and5. In this embodiment, the fluid conduit systems600and600′ are identical. Thus, only one of the fluid conduit systems600and600′ is described in detail. The fluid conduit system600comprises a first joint610, a second joint620and a tube630. The first joint610is mounted to the wafer cleaner220. The second joint620is mounted to the bottom housing12of the polishing apparatus10. Alternatively, the second joint620can be mounted to a floor of a facility where the polishing apparatus10is installed instead of the bottom housing12. As best shown inFIG. 11, a first end630aof the first tube630is connected to the first joint610such that the tube630can pivot about the first joint610. A second end630bof the tube630is connected to the second joint620such that the tube630can also pivot about the second joint620. As illustrated with the arrow E inFIG. 10, the tube630can pivot about the first joint610and the second joint620when the wafer cleaners220is pivoted away from the polishing station20. The fluid conduit system600′ operates in a similar fashion when the wafer cleaner220′ is pivoted away from the polishing station20, as illustrated with the arrow F inFIG. 10.

Users can access the polishing units250and the wafer relay devices280of the polishing station20either from the space between the pivoted first wafer cleaner220and the longer side20L of the polishing station20or the space between the pivoted second wafer cleaner220′ and the longer side20L′ of the polishing station20in order to maintain the wafer relay devices280and the polishing units250, as illustrated inFIG. 10.

In the polishing apparatus10, the wafer cleaners220and220′ can be moved manually by the users or automatically using pneumatic or mechanical force. Conventional ancillary devices (not shown) can be used to transfer the pneumatic or mechanical force, which may be generated by a suitable mechanism, such as pumps or motors, to the wafer cleaners220and220′ in order to move the wafer cleaners.

Turning now toFIG. 12, a polishing apparatus800in accordance with another embodiment of the present invention is described. The polishing apparatus800includes some of the components of the polishing apparatus10ofFIG. 1. Thus, the reference numbers used inFIG. 1will be used inFIG. 12to identify common components. The polishing apparatus800comprises a polishing station820, the wafer storage station102, the optional buffer station105, the first wafer transport device150, the second wafer transport device210, and a wafer cleaning system830.

The polishing station820is similar to the polishing station20of the polishing apparatus10. The polishing station820is an enclosed structure with window-like mechanisms (not shown) that can be opened to transfer semiconductor wafers into and out of the polishing station820. As illustrated inFIG. 12, the polishing station820in this embodiment is rectangular in shape with two longer sides and two shorter sides. The polishing station820comprises the polishing units250aand250b, the first two wafer relay devices280aand280a′, the second two wafer relay devices280band280b′, and the third two wafer relay devices280cand280c′. However, the polishing station820further comprises a third polishing unit250cand fourth two wafer relay devices280dand280d′. The third polishing unit250cis structurally similar to the polishing units250aand250b. Thus, the polishing unit250ccomprises a polishing table256c, a first wafer carrier assembly260cand a second wafer carrier assembly260c′. Each of the wafer carrier assemblies260cand260c′ comprises a wafer carrier262, a carrier shaft264and a rotational-and-vertical drive mechanism266, as illustrated inFIGS. 2 and 3.

In the polishing station820, the third polishing unit250cis positioned next to the third wafer relay devices280cand280c′ such that wafers can be transferred from the third wafer relay devices280cand280c′ to the wafer carriers262cand262c′ of the third polishing unit250c, respectively. The fourth wafer relay devices280dand280d′ are positioned next to the third polishing unit250csuch that wafers that were polished at the third polishing unit150ccan be transferred from the wafer carriers262cand262c′ of the third polishing unit250cto the fourth wafer relay devices280dand280d′, respectively.

The wafer cleaning system830comprises the first wafer cleaner220and the second wafer cleaner220′, which are attached to each other. In order to minimize the width of the polishing apparatus800, the wafer cleaners220and220′ are preferably positioned such that the longer side220L of the first wafer cleaner220is facing to the longer side220L′ of the second wafer cleaner220, as illustrated inFIG. 12. As a result, the wafer cleaning system830in this embodiment is also rectangular in shape with two longer sides and two shorter sides. The wafer cleaning system830is positioned such that the longer side830L of the wafer cleaning system800is facing the longer side820L of the polishing station820, as illustrated inFIG. 12. The area of the polishing station820is an area roughly defined by the polishing tables256a,256band256c.

The first wafer transport device150is situated on a linear track855, which allows the first wafer transport device150to access the wafer storage station102, the buffer station105, the first wafer relay devices280aand280a′ of the polishing station820and the drying stations228and228′ of the first and second wafer cleaners220and220′. Thus, the first wafer transport device150can transfer wafers between the wafer storage station102, the buffer station, the first wafer relay devices280aand280a′ of the polishing station820and the drying stations228and228′ of the first and second wafer cleaners220and220′.

The second wafer transport device210is situated on a linear track815, which allows the second wafer transport device210to access the wafer receiving stations222and222′ of the first and second wafer cleaners220and220′ and the third wafer relay devices280cand280c′ and the fourth wafer relay devices280dand280d′ of the polishing station820. The second wafer transport device210transfers wafers from the polishing station820to the first and second wafer cleaners220and220′ of the wafer cleaning system830. More specifically, the second wafer transport device210transfers wafers from the fourth wafer relay devices280dand280d′ of the polishing station820to the wafer receiving stations222and222′ of the first and second wafer cleaners220and220′. The second wafer transport device210can also transfer wafers from the third wafer relay devices280cand280c′ of the polishing station820to the wafer receiving stations222and222′ of the first and second wafer cleaners220and220′.

In an alternative embodiment of the present invention, the first two wafer relay devices280aand280a′ of the polishing station820in the polishing apparatus800ofFIG. 12can be removed. In this embodiment, the first wafer transport device150transfers wafers directly to the wafer carriers262aand262a′ of the first polishing unit250a.

In another alternative embodiment of the present invention, the fourth two wafer relay devices280dand280d′ of the polishing station820in the polishing apparatus800ofFIG. 12can be removed. In this embodiment, the second wafer transport device210transfers wafers directly from the wafer carriers262cand262c′ of the third polishing unit250cto the first and second wafer cleaners220and220′.

In another alternative embodiment of the present invention, the first and fourth wafer relay devices280a,280a′,280dand280d′ of the polishing station820in the polishing apparatus820ofFIG. 12can be removed. In this embodiment, the first wafer transport device150transfers wafers directly to the wafer carriers262aand262a′ of the first polishing unit250a. The second wafer transport device210transfers wafers directly from the wafer carriers262cand262c′ of the third polishing unit250cto the first and second wafer cleaners220and220′.

Methods of processing wafers in the polishing apparatus800ofFIG. 12in accordance with an embodiment of the invention is similar to the methods of processing wafers in the polishing apparatus10ofFIG. 1, as described above, except that the wafers can be further polished at the third polishing unit250cand the wafers are transferred from the fourth wafer relay devices280dand280d′ or the wafer carriers262cand262c′ of the third polishing unit250cto the first and second wafer cleaners220and220′.

Similar to the wafer cleaners220and220′ of the polishing apparatus10ofFIGS. 1,6and9, the wafer cleaning system830of the polishing apparatus800is also movable so that users can access the interface between the polishing station820and the wafer cleaning system830. In order to facilitate this movement of the wafer cleaning system830, the polishing apparatus800includes one or more guide mechanisms (not shown inFIG. 12) to allow the wafer cleaning system830to be moved. As an example, the polishing apparatus800may include linear guide mechanisms370, as illustrated inFIGS. 6-8, which are connected to the polishing station820and the wafer cleaning system830so that the wafer cleaning system830can be linearly displaced along a direction orthogonal to the longer side820L of the polishing station820using the linear guide mechanisms370, as illustrated inFIG. 12with the arrow A. As another example, the polishing apparatus800may include the pivoting guide mechanisms500, as illustrated inFIGS. 9-11, which are connected to the polishing station820and the wafer cleaning system830so that the wafer cleaning system830can be pivoted away from the polishing station820and then pivoted back to the polishing station820.

When users need to access the interface between the polishing station820and the wafer cleaning system830, the wafer cleaning system830is moved away from the polishing station820, as illustrated inFIG. 12with the arrow A. After the wafer cleaning system300is moved away from the polishing station820, users can access the first and second wafer relay devices280aand280b, the wafer carrier assembly260aand the polishing table256aof the polishing station820in order to maintain them. Users can also access the wafer cleaning system830from the side830L facing the polishing station20in order to maintain the wafer cleaning system830. After maintaining them, the wafer cleaning system830can be moved back to its original operational position such that the second wafer transport device210can transfer wafers to the wafer cleaning station830.

The polishing apparatus800can be modified to comprise the polishing station20, as illustrated inFIG. 1, instead of the polishing station820. In this embodiment, the second wafer transport device210transfers wafers directly from the third wafer relay devices280cand280c′ to the first and second wafer cleaners220and220′. If the polishing station20does not include the third wafer relay devices280cand280c′, then the second wafer transport device210transfers wafers directly from the wafer carriers262band262b′ of the second polishing unit250bto the first and second wafer cleaners220and220′.

Similarly, the polishing apparatus10can be modified to comprise the polishing station820, as illustrated inFIG. 12, instead of the polishing station20. In fact, the polishing apparatuses10and800can be modified to comprise a polishing station having any number of polishing units250and any number of wafer relay devices280.

A method of polishing objects, such as semiconductor wafers, in accordance with an embodiment of the invention is described with reference to a flow diagram ofFIG. 13. At block902, a first object is transferred from a first object carrier of a first polishing unit to a first object relay device and from the first object relay device to a first object carrier of a second polishing unit along an original direction within a polishing station. In addition, at block902, the first object is polished at the first and second polishing units. At block904, a second object is transferred from a second object carrier of the first polishing unit to a second object relay device and from the second object relay device to a second object carrier of the second polishing unit along the original direction within the polishing station. In addition, at block904, the second object is polished at the first and second polishing units. At block906, the first object is transferred from the polishing station to a first object cleaner and the second object is transferred from the polishing station to a second object cleaner. Each of the first and second object cleaners includes a cleaning station and a drying station. At block908, the first object is processed at the cleaning station and the drying station of the first object cleaner such that the first object is transferred along a return direction within the first object cleaner. The return direction is the opposite direction of the original direction. At block910, the second object is processed at the cleaning station and the drying station of the second object cleaner such that the second object is transferred along the return direction within the second object cleaner.