1. Field of the Invention
Embodiments of the present invention generally relate to methods and apparatus for chemical mechanical polishing (CMP) of substrates.
2. Description of the Related Art
CMP is a known process used to planarize one or more surfaces of a substrate. Although many commercially available CMP systems have demonstrated robust polishing performance, the move to smaller line widths requiring more precise fabrication techniques, along with a continued need for increased throughput, drives an ongoing effort for polishing system improvements. As fabrication techniques continue to improve, CMP platform architecture must adapt to not only utilize the techniques, but to also polish substrates in an efficient and cost effective manner. Since fabrication techniques are constantly changing, and the variety of substrates to be processed is constantly increasing, existing CMP platform architectures may not be the most efficient tools for processing substrates.
Therefore, there is a need for new CMP platform architectures for processing substrates.
Embodiments of the invention provide polishing systems for increasing production efficiency, maximizing substrate throughput, and reducing production costs. The polishing systems generally include one or more polishing stations for performing a CMP process and one or more cleaning stations at which post-polishing cleaning is performed. The number of cleaning stations and polishing heads present may be increased depending on the desired substrate throughput or processing time at each polishing station. The number of polishing stations or cleaning stations can also be reduced in order to reduce the footprint of the polishing system. The polishing pads at each polishing station can be adjusted in size to accommodate one or more polishing heads simultaneously depending on substrate throughput and system footprint. Additionally, the polishing pads may be replaced with a fixed abrasive pad, or adapted to polish 450 millimeter substrates.
In one embodiment, a polishing system comprises a polishing module having at least three polishing stations and a circular track disposed above the at least three polishing stations. At least six polishing heads are coupled to the circular track. The polishing system further comprises a cleaning module in operable communication with the polishing module. The cleaning module has two cleaning stations and a central transfer area disposed between the two cleaning stations. The central transfer area is in operable communication with a factory interface. Each of the two cleaning stations are separated from the central transfer area by a wall.
In another embodiment, a polishing system comprises a polishing module having at least three polishing stations and a circular track disposed over the at least three polishing stations. Each polishing station has a polishing pad adapted to polish one substrate thereon. The polishing system further comprises a cleaning module having a central transfer area and a cleaning module. The central transfer area is separated from the cleaning module by a wall.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.
Embodiments of the invention provide polishing systems for increasing production efficiency, maximizing substrate throughput, and reducing production costs. The polishing systems generally include one or more polishing stations for performing a CMP process and one or more cleaning stations at which post-polishing cleaning is performed. The number of cleaning stations and polishing heads present may be increased depending on the desired substrate throughput or processing time at each polishing station. The number of polishing stations or cleaning stations can also be reduced in order to reduce the footprint of the polishing system. The polishing pads at each polishing station can be adjusted in size to accommodate one or more polishing heads simultaneously depending on desired substrate throughput and system footprint. Additionally, the polishing pads may be replaced with a fixed abrasive pad, or adapted to polish 450 millimeter substrates.
The factory interface 103 is positioned adjacent to and in operable communication with the cleaning module 102A. The cleaning module 102A includes two cleaning stations 109A, 109B, a central transfer area 112 located therebetween, and a shuttle trough 113 positioned at one end of the cleaning module 102A opposite the factory interface 103. The utilization of two separate cleaning stations 109A, 109B allows for one of the cleaning stations 109A, 109B to be shut down for maintenance, while the other cleaning station continues to process substrates. Thus, throughput is merely reduced, and not halted, when cleaning or maintenance of one of the cleaning stations 109A, 109B is desired. Additionally, separation of the cleaning stations 109A, 109B reduces the probability of cross-contamination within the cleaning stations 109A, 109B. For example, if different polishing processes are being performed at different polishing stations 128A within the polishing module 101A, then each of the cleaning stations 109A, 109B may be dedicated to cleaning substrates coming from selected polishing stations 128A. In this manner, a unique cleaning process may be matched with a specific polishing process so that the cleaning stations 109A, 109B cannot be contaminated with substrates processed in a polishing station 128A running a different polishing process.
The cleaning stations 109A, 109B are separated from the central transfer area 112 by walls 117. The wall 117 facilitates environmental isolation between the central transfer area 112 and each of the cleaning stations 109A, 109B. The cleaning stations 109A, 109B and the central transfer area 112 are in communication with one another through the shuttle trough 113, which may be selectively partitioned further facilitate environmental isolation between the central transfer area 112 and each of the cleaning stations 109A, 109B. Each cleaning station 109A, 109B includes a plurality of cleaning units 115 and a dryer 120, each of which generally includes an opening formed in the upper portion thereof for accepting substrates therein. The cleaning units 115 may be one or more of brush boxes, rinsing stations, spray jet units, megasonic cleaners, or combinations of two or more thereof. Robots 116a, 116b are each connected to a track disposed in each of the cleaning stations 109A, 109B and coupled to a surface of the walls 117. The robots 116a, 116b are adapted to move a substrate received from the shuttle trough 113 through each of the cleaning units 115 to the dryer 120. The dryer 120 has an output station (not shown) through which the substrate is presented for transfer to the robot 104, which then stores the substrate in the substrate storage cassettes 107. For example, a first robot 116a may be adapted to move substrates through a first set of cleaning units 115, such as the first two cleaning units 115, while a second robot 116b may be adapted to move the substrate through a second set of cleaning units 115 and the dryer 120. The use of two robots 116a, 116b minimizes cross-contamination between the cleaning units 115 and the dryer 120 while improving throughput.
The central transfer area 112 of the cleaning module 102A is in communication with the factory interface 103 and the polishing module 101A through ports 110 and 118, respectively, each of which may be independently opened and closed. The central transfer area 112 includes two transfer platforms 180 to facilitate transfer of substrates, two buffer stations 108A, 108B and a robot 119 adapted to transfer substrates from the transfer platforms 180 to the interior of the polishing module 101A through the ports 118. One or more substrates may optionally be vertically positioned in the buffer stations 108A, 108B, which contain a solution such as deionized water, to mitigate process delays due to robot transfer times, or to store substrates therein during tool faults or process delays. In such an embodiment, the robot 119 may remove substrates from the buffer stations 108A, 108B as needed. Storing substrates vertically allows for more substrates to be stored in a smaller area, thereby reducing the footprint of the central transfer area 112. The robot 119 includes a linkage assembly 124 coupled to an overhead track or linkage (not shown), a robot body 127 coupled to the linkage assembly 124, and two end effectors 126 coupled to the robot body 127. The robot 119 is adapted to remove substrates from the transfer platforms 180 and transfer the substrates into the polishing module 101A to load cups 121A and 121B through the port 118. The robot 119 is also adapted to remove substrates from the load cups 121A and 121B after a polishing process, and dispose the substrates in the shuttle trough 113 through an opening 125 located in the upper surface of the shuttle trough 113. The end effectors 126 each generally include at least one gripping device, such as a mechanical clamp or suction device, in order to secure substrates thereto.
The shuttle trough 113 accepts substrates in a vertical orientation for placement on shuttles 138 located therein. The shuttles 138 then transfer the substrates to a location proximate the cleaning stations. 109A, 109B (i.e., adjacent to openings 137) to facilitate transfer of the substrates to the robots 116a. The robot 119 is adapted to pivot at the connection between the robot body 127 and the linkage assembly 124 to allow the end effectors 126 to assume a vertical orientation for transfer of polished substrates through the opening 125 located in the shuttle trough 113.
The polishing module 101A includes a plurality of polishing stations 128A on which substrates are polished on polishing pads 135 while retained in polishing heads 131. In the embodiment of
The polishing heads 131 are coupled to carriages that are mounted to an overhead track 130 (shown in phantom) having a curved shape. The overhead track 130 allows the polishing heads 131 to be selectively positioned around the polishing module 101A including over the polishing pads 135 disposed in the polishing stations 128A and load cups 121A and 121B. Thus, the polishing heads 131 are movable along the track 130 to a position over the load cups 121A and 121B where substrates can be engaged and retained by the polishing heads 131. The polishing heads 131 can then return to a position over a selected one of the polishing stations 128A via movement along the track 130 for polishing of the substrates on the polishing pads 135.
The above description describes the structure of the polishing system 100A; and now the movement of substrates through the polishing system 100A will be described. The robot 104 unloads substrates 106 from the substrate storage cassettes 107 and transfers the substrates to the transfer platforms 180 through the port 110. The robot 119 then engages and lifts one substrate from each of the transfer platforms 180 simultaneously. The robot rotates approximately 180 degrees and enters the polishing module 101A to position the substrates on the load cups 121A, 121B through the port 118. The robot 119 is then retracted from the polishing module 101A.
Two polishing heads 131 travel along the track 130 to a position above the load cups 121A and 121B. The polishing heads 131 actuate downward to engage and secure a substrate from each of the load cups 121A and 121B. The polishing heads 131 then lift upward to provide sufficient clearance of the load cups 121A and 121B, and move to a position above one of the polishing stations 128A for polishing of the secured substrates. The remaining polishing heads 131 may likewise secure substrates from the load cups 121A, 121B after substrates have been placed thereon by the robot 119. It is contemplated that each polishing station may have a different polishing process performed thereon, and thus, substrates may proceed though each polishing station in a clockwise or counterclockwise direction until returning to the load cups 121A, 121B where the substrates can then be removed from the polishing module 101A. Alternatively, similar polishing processes may be performed at each polishing station 128A, and thus, the substrates need not be polished at each polishing station 128A prior to returning to the load cups 121A, 121B.
After completion of the polishing of the substrates located in polishing heads 131, the polishing heads 131 rotate along the track to a position over the unoccupied load cups 121A, 121B, and transfer the polished substrates to the load cups 121A, 121B for removal from the polishing module 101A by the robot 119. The robot 119 removes the polished substrates from the load cups 121A, 121B and disposes the polished substrates in the opening 125 of the shuttle trough 113. Each of the polished substrates is disposed on the shuttle 138 located within the shuttle trough 113, and transferred via the shuttle 138 to one of the cleaning stations 109A, 109B. The shuttles 138 are independently operable to allow a first shuttle 138 to carry a first substrate to the cleaning station 109A, and to allow a second shuttle 138 to carry a second substrate in an opposite direction to cleaning station 109B.
The polished substrates are then removed from the shuttle trough 113 through openings 137 by respective robots 116a, 116b located in each of the cleaning stations 109A, 109B. A first robot 116a in each of the cleaning stations 109A, 109B advances the polished substrate through a first set of the cleaning units 115, such as the first two cleaning units 115. A second robot 116b in each of the cleaning stations 109A, 109B removes the substrate from the last cleaning unit 115 of the first set of cleaning units 115, and then advances the substrate through the remainder of the cleaning units 115 and the dryer 120. The cleaned substrates are then removed from the cleaning stations 109A, 109B by the robot 104 and stored in the substrate storage cassettes 107. The use of two robots 116a, 116b minimizes cross-contamination between the cleaning units 115 and the dryer 120 while improving throughput.
The polishing system 100A illustrated in
The combination of the fixed abrasive pad 122 along with the polishing pads 135 increases process flexibility of the polishing system 100B. For example, fixed abrasive polishing pads may be more efficient at polishing specific materials, or may be more beneficial for bulk removal steps. Thus, the combination of the fixed abrasive pad 122 and the polishing pads 135 may allow for more efficient polishing of substrates, thereby increasing throughput and reducing production costs. It should be noted that although the fixed abrasive pad 122 is positioned between two polishing pads 135 in the embodiment illustrated in
The polishing system 100C also includes a cleaning module 102C. The cleaning module 102C is similar to the cleaning module 102A (shown in
The cleaning module 102E is similar to the cleaning module 102C (shown in
Although the polishing module 101F is shown having six polishing stations 128C, it is contemplated that the polishing module 101F may include less than six polishing stations 128C. For example, the polishing module 101F may have four polishing stations 128C or five polishing stations 128C. In embodiments where the polishing module 101F includes less than six polishing stations 128C, the position of the polishing stations 128C in the polishing module 101F may be rearranged in order to minimize the footprint of the polishing module 101F.
The first area 160A of the polishing module 101G includes a polishing station 128A adapted to polish two substrates simultaneously thereon, and two load cups 121A, 121B adapted to accept substrates from the robot 119E through an opening 118A. A track 130 is positioned over the load cups 121A, 121B and the polishing station 128A and has polishing heads 131 coupled thereto to facilitate transfer of substrates from the load cups 121A, 121B to the polish station 128A. In the embodiment illustrated in
The second area 160B includes a polishing station 128G having three edge polishers 155 adapted to polish, grind, or bevel the edges of substrates located at the polishing station 128G. The polishing station 128G is shown as having three edge polishers 155, however, it is contemplated that the polishing station 128G may be adapted to polish any number of substrates simultaneously. The polishing station 128G includes four substrate support positions 156 located on a support 157. A first substrate support position 156 does not have an edge polisher 155 positioned adjacent thereto which allows for loading or unloading of substrates thereon via the robot 119G. Once a substrate has been loaded onto the exposed substrate support position 156, the support 157 rotates in order to provide an unoccupied substrate support position 156 for loading of an additional substrate onto the support 157. After three substrates have been loaded onto the support 157, a polishing process is then performed on the substrates by the edge polishers 155. After completion of the polishing process, the support 157 continues to rotate to facilitate unloading of polished substrate and loading of unpolished substrates onto the support 157.
The second area 160B also includes the load cup 121C therein. The load cup 121C facilitates transfer of substrates from the robot 119E to the robot 119G when the movable door 151 is extended from the housing 150. With the movable door 151 in the closed position, the robot 119E can remove a polished substrate from one of the load cups 121A, 121B through the opening 118A, and then position the substrate on the load cup 121C through the opening 118B for polishing at the polishing station 128G. Thus, the areas 160A and 160B can remain environmentally isolated to reduce cross-contamination therebetween while still allowing for transfer of substrates from one area to the other. It is contemplated that substrates may first be positioned in the second side 160B and the transferred to the first side 160A, as desired.
Rotatable fluid delivery arms 136 are positioned on opposite sides of the platen 242 and are adapted to apply one or more fluids to the upper surface of the polishing pad 135. For example, the fluid delivery arms 136 may apply one or more of a polishing slurry, a polishing fluid, a rinsing solution, or a conditioning solution to the upper surface of the polishing pad 135. Rotatable pad conditioners 134 are positioned adjacent to each of the fluid delivery arms 136. The pad conditioners 134 are adapted to contact and sweep across the polishing pad 135 to condition the upper surface thereof.
Benefits of the present invention include polishing systems for CMP processes to increase efficiency and throughput while reducing production costs. The use of additional polishing heads or the polishing of multiple substrates on a single pad can increase substrate throughput. Additionally, polishing processes utilizing both a polishing pad and a fixed abrasive pad can likewise increase substrate throughput. The cost to manufacture devices can be reduced by utilizing a polishing system having a smaller footprint, thus reducing the amount of space required to manufacture the devices.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.