Embodiments of the presently disclosed subject matter generally relate to apparatus, system, and methods for in-line post polish cleaning of substrates, such as semiconductor substrates.
An integrated circuit is typically formed on a substrate (e.g., a semiconductor wafer) by the sequential deposition of conductive, semiconductive, or insulative layers on the substrate, and by the subsequent processing of the layers.
One fabrication step involves depositing a filler layer over a non-planar surface disposed on the substrate and planarizing the filler layer until the non-planar surface is exposed. For example, a conductive filler layer can be deposited on a patterned insulative layer disposed on the substrate to fill the trenches or holes in the insulative layer. The filler layer is then polished until the raised pattern of the insulative layer is exposed.
Chemical mechanical polishing (CMP) is one accepted method of planarization known in the art. This planarization method typically requires that the substrate be mounted on a carrier head. The exposed surface of the substrate is placed against a rotating polishing pad. The carrier head provides a controllable load on the substrate to push it against the polishing pad. For example, the carrier head may provide a specified pressure on the backside of the substrate to push it against the polishing pad. A polishing liquid, such as a slurry with abrasive particles, is supplied to the surface of the polishing pad. For example, cerium-based slurries, such as slurries containing cerium oxide, can be used in the polishing of a semiconductor or insulating thin layer in CMP.
The slurry of abrasive particles can include cerium oxide particulates and other additives which contribute to the polishing process. The benefits allow the substrates to be polished with stability without generating scratches. To remove these particulates, the substrates can be subjected to a cleaning process that can include the use of harsh oxidizing solvents. For example, a mixture of sulfuric acid and hydrogen peroxide (i.e., sulfuric peroxide mixture (SPM)) can be used in the removal or dissolution of cerium oxide particulates from the surfaces of a substrate after polishing. SPM cleaning can be performed in a parallel separated mode in which each substrate is placed in a bath in a separate tank. Typically, the SPM cleaning process is performed in a separate wet bench apparatus in which wafers are inbound in a dry state after the CMP polishing. It is performed to accommodate other methods of post-CMP cleaning when cerium oxide particulates are not sufficiently removed.
The substrates are generally processed through an SPM cleaning tank in batches. This method is not compatible with CMP polishing platforms based on single-wafer processing since the cleaning tank will require its lids to open over the frequency of the platform's throughput. When the lid of the SPM tank opens, steam and sulfuric vapors will escape causing a change in temperature, bath concentration, as well as increasing the risk of cross contamination of the process. In addition, each wafer will be exposed over different rates of its process which will pose additional control challenges. Based on the above, there is a need for improvement in the method to allow the integration of an SPM process to work within a single-wafer processing platform for post-CMP cleaning.
Embodiments described herein generally relate to apparatus, systems, and methods for semiconductor processing. More particularly embodiments herein provide a post-chemical mechanical polishing cleaning system configured to process substrates individually and in batches.
In one embodiment, a system for cleaning a substrate is provided. The system includes an input tank, a cleaning tank, a rinse tank, an output tank, and a robot system including a plurality of robot arms configured to transfer a substrate carrier between the input tank, the cleaning tank, the rinse tank, and the output tank. The cleaning tank is configured to contain a cleaning fluid for applying to the substrate. The cleaning tank includes a top surface and an outer surface adjacent to the top surface. The top surface and the outer surface define an inner volume. The outer surface includes an upper portion and a lower portion. The cleaning tank further includes a transport system connected to the upper portion of the cleaning tank, the lower portion of the cleaning tank, or a combination thereof. The transport system is configured to transport the substrate carrier containing the substrate. The cleaning tank further includes a stationary lid covering a majority of the top surface of the cleaning tank, at least one input lid assembly adjacent to a first side of the stationary lid, and at least one output lid assembly adjacent to a second side of the stationary lid. The at least one input lid assembly, the stationary lid, and the at least one output lid assembly cover an entirety of the top surface.
In another embodiment, a substrate carrier is provided. In this embodiment, the substrate carrier includes a carrier body, at least one lift handle feature incorporated in an upper portion of the carrier body, a substrate holder at a bottom inner surface of the carrier body configured to hold a substrate, and a protrusion extending from an outer surface of the carrier body. The substrate carrier is further configured to be transported by a transport system in a post-CMP cleaning system.
In yet another embodiment, a system for cleaning a substrate after chemical mechanical polishing is provided. In this embodiment, the system includes an input tank, a cleaning tank including a transport system, a substrate carrier, a rinse tank, an output tank, one or more wet robots, a substrate carrier robot system, and a controller. The controller is configured to insert the substrate into a substrate carrier in the input tank using the one or more wet robots, transfer the substrate carrier from the input tank to the cleaning tank using the substrate carrier robot system, transport the substrate in the substrate carrier through the cleaning tank for a predetermined period using the transport system, remove the substrate carrier from the cleaning tank using the substrate carrier robot system, insert the substrate carrier into the rinse tank using the substrate carrier robot system, rinse the substrate in the substrate carrier in the rinse tank, remove the substrate carrier from the rinse tank using the substrate carrier robot system, place the substrate carrier into the output tank using the substrate carrier robot system, and remove the substrate from the substrate carrier using the substrate carrier robot system.
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, 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 exemplary embodiments and are therefore not to be considered limiting of the scope of the disclosure, as the disclosure 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 and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Sulfuric peroxide mixture (SPM) cleaning can be performed in a parallel separated mode in which each substrate is placed in a bath in a separate processing chamber, or tank. Although this permits parallel processing of multiple substrates, the use of separate tanks can increase the use of the processing chemistry, e.g., the sulfuric acid and hydrogen peroxide. Further, the chemistry may not be reusable, i.e., new chemistry may be needed for each substrate. This chemistry can be a significant expense.
Moreover, the time required for SPM processing can be fairly large relative to the polishing time, e.g., by a factor of 10 or more. Thus, in order to match the throughput of the polishing system so that SPM process is not gating the throughput, a large number of substrates would need to be processed in parallel by SPM. However, including multiple SPM tanks with each chamber processing a single substrate might not be feasible, due to cost, available footprint in the clean room, or chemistry expense.
An SPM cleaning tank may also have a large lid substantially spanning the length of the tank that opens to allow substrates to enter that tank. When the lid of the SPM cleaning tank opens, heated SPM vapor is released which changes the concentration of the SPM, lowers the temperature of the SPM, and corrodes equipment external to the cleaning tank. In addition, the risk of cross-contamination increases when the lid is opened and exposing the contents of the cleaning tank.
An approach that addresses one or more of these issues includes an SPM processing system in which multiple substrates are processed in the same tank while sharing and maintaining the chemistry of the SPM.
The factory interface module 102 includes a support to hold a plurality of cassettes 110, a housing 111 that encloses a chamber, and one or more interface robots 112. The interface robot 112 generally provides the range of motion required to transfer substrates between the cassettes 110 and one or more of the other modules of the CMP system 100.
Unprocessed substrates are generally transferred from the cassettes 110 to the input module 104 by the interface robot 112. The input module 104 generally facilitates transfer of a substrate between the interface robot 112 and a transfer robot 114. The transfer robot 114 transfers the substrate between the input module 104 and the polishing module 106.
The polishing module 106 generally comprises a transfer station 116, and one or more polishing stations 118. The transfer station 116 is disposed within the polishing module 106 and is configured to accept the substrate from the transfer robot 114. The transfer station 116 transfers the substrate to at least one carrier head 124 of a polishing station 118 that retains the substrate during polishing.
The polishing stations 118 each includes a rotatable disk-shaped platen on which a polishing pad 120 is situated. The platen is operable to rotate about an axis. The polishing pad 120 can be a two-layer polishing pad with an outer polishing layer and a softer backing layer. The polishing stations 118 each further includes a dispensing arm 122, to dispense a polishing liquid, e.g., an abrasive slurry, onto the polishing pad 120. In the abrasive slurry, the abrasive particles can be silicon oxide, but some polishing processes use cerium oxide abrasive particles. Each polishing station 118 can also include a conditioner head 123 to maintain the polishing pad 120 at a consistent surface roughness.
The polishing stations 118 each includes at least one carrier head 124. The at least one carrier head 124 is operable to hold a substrate against the polishing pad 120 during a polishing operation. Following the polishing operation performed on a substrate, the at least one carrier head 124 transfers the substrate back to the transfer station 116.
The transfer robot 114 then removes the substrate from the polishing module 106 through an opening connecting the polishing module 106 with the remainder of the CMP system 100. The transfer robot 114 removes the substrate in a horizontal orientation from the polishing module 106 and transfers the substrate to the cleaning module 108.
The cleaning module 108 generally includes one or more cleaning devices that can operate independently or in concert. For example, the cleaning module 108 can include, from top to bottom in
Although
As described above, the CMP system 100 transfers the substrates from the polishing module 106 into the cleaning module 108. Debris from the polishing process, e.g., abrasive particles or organic materials from the polishing pad or slurry, can be stuck to the substrates. Some of these materials, e.g., cerium oxide particulates, and organic additives from the polishing module 106, are difficult to remove with the cleaners 131, 132, 133 listed above. Therefore, the substrates are moved to the in-line SPM module 128 within the cleaning module 108. The SPM module 128 shown in
The CMP system 100 includes a controller 160 generally includes one or more processors, memory, and support circuits. The one or more processors may include a central processing unit (CPU) and may be one of any form of a general purpose processor that can be used in an industrial setting. The memory, or non-transitory computer-readable medium, is accessible by the one or more processors and may be one or more of memory such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. The support circuits are coupled to the one or more processors and may comprise cache, clock circuits, input/output subsystems, power supplies, and the like. The various methods disclosed herein may generally be implemented under the control of the one or more processors by the one or more processors executing computer instruction code stored in the memory as, for example, a software routine. When the computer instruction code is executed by the one or more processors, the one or more processors controls the CMP system 100 to perform processes in accordance with the various methods disclosed herein.
The cleaning tank 125 may also comprise injectors or dispersion plates (not shown) at a bottom of the cleaning tank 125 to introduce a laminar flow of chemicals into the cleaning tank 125. The cleaning tank 125 has a stationary lid 127 located at the top surface 125b of the cleaning tank 125. The stationary lid 127 may be hinged and may be opened for maintenance of the cleaning tank 125, but remains stationary during SPM cleaning of substrates. Preferably, the stationary lid 127 covers a majority of the top surface 125b of the cleaning tank 125. The cleaning tank 125 also has an input lid assembly 150a at an entry point in the cleaning tank 125, and an output lid assembly 150b at an exit point in the cleaning tank 125. The input lid assembly 150a and the output lid assembly 150b are disposed on opposing sides of the stationary lid 127. The input lid assembly 150a and the output lid assembly 150b each exposes a portion of an upper end of the cleaning tank 125, and may be actuated independently by the controller 160 (
Depicted on the left of the cleaning tank 125 is an input tank 180 where a first wet robot 139a, controlled by the controller 160, places a substrate 10a to be cleaned into a substrate carrier 210. A first carrier transfer robot arm 137a, controlled by the controller 160, then grasps the substrate carrier 210 containing the substrate 10a and removes it from the input tank 180.
The controller 160 actuates the input lid assembly 150a to an open position. For example, the input lid assembly 150a may be hinged and opened via an actuator such as a motor, slidingly retracted via an actuator such as a motor or cylinder, or lifted via an actuator such as a robot arm. The first carrier transfer robot arm 137a then places the substrate carrier 210 through the opened input lid assembly 150a, submerging the substrate carrier 210 into the SPM 135 disposed in the cleaning tank 125 and onto a transport system, i.e., conveyor system 220. The conveyor system 220 is located on an upper portion 225a of the outer surface 125b of the cleaning tank 125. The first carrier transfer robot arm 137a retracts out of the cleaning tank 125, and the input lid assembly 150a closes, sealing the cleaning tank 125.
The conveyor system 220 may include a pair of continuous conveyor belts or linkages on a single or opposing sides of the cleaning tank 125 whose operating length spans the length of the cleaning tank 125. The continuous belts may each be a plurality of separate belts, such as three, whose total operating length spans the length of the cleaning tank 125. The substrate carrier 210 is placed onto an upper surface of each belt 219. Each belt 219 is actuated, for example by a motor, such that the substrate carrier 210 moves along the length of the belt 219 at a desired speed. The conveyor system 220 is controlled by the controller 160 to operate in sync to transport the substrate carrier 210 across the length of the cleaning tank 125 to a predetermined position under the output lid assembly 150b. The conveyor system 220 is actuated in such a manner as to cause a first isolation gap 230a from when the substrate carrier 210 is initially placed into the cleaning tank 125 and other substrate carriers already being processed within the cleaning tank 125. The first isolation gap 230a may be created by an initial pause at the beginning of the conveyor system 220 and then an increase in speed to match a predetermined gap 232 between other substrate carriers. Preferably, the substrate carrier 210 reaches the predetermined gap 232 while under the stationary lid 127. The conveyor system 220 may comprise multiple belts, such as three, where each belt has its own speed control. Alternatively, the conveyor system 220 may be disposed on an upper portion of the tank body 225a, a lower portion of the tank body 225b, or a combination thereof. The substrate carrier 210 then follows a motion path 240, via the conveyor system 220 while being processed. Before reaching the output lid assembly 150b, the conveyor system 220 is actuated to create a second isolation gap 230b in a similar manner to which the conveyor system 220 created the first isolation gap 230a. The output lid assembly 150b is actuated by the controller 160 into an open position similar to the input lid assembly 150a. Once the substrate carrier 210 moves across the second isolation gap 230b, a second carrier transfer robot arm 137b, controlled by the controller 160, lifts the substrate carrier 210 out of the SPM 135 and out of the cleaning tank 125 through the opened output lid assembly 150b. Once the substrate carrier 210 is out of the cleaning tank 125, the output lid assembly 150b is actuated into a closed position by the controller 160 in a similar manner to the input lid assembly 150a, sealing the cleaning tank 125.
The second carrier transfer robot arm 137b, controlled by the controller 160, then places the substrate carrier 210 into the hot/cold rinse tank 126 for processing. The hot/cold rinse tank 126 may also be configured similarly to the cleaning tank 125 and include a separate conveyor system and lid assembly system. The hot/cold rinse tank 126 is equipped for hot rinsing of sulfuric residues without shocking the substrate after SPM cleaning plus a cold de-ionized water rinse to cool the substrate to room temperature. This rinsing also cleans residue from the substrate carrier 210. When the substrate has been processed through the hot/cold rinse tank 126, the second carrier transfer robot arm 137b transfers the substrate carrier 210 into an output tank 182. The cleaned substrate 10b is removed from the substrate carrier 210 and transferred out for further processing in the CMP system 100 by a second wet robot 139b controlled via the controller 160. The substrate carrier 210 is then transferred back to the input tank 180 to receive another substrate via the first and/or second carrier transfer robot arms 137a, 137b.
The system described in
As shown in
Alternative methods to the conveyor system described in
Upon a signal from the controller 160 (
As shown in
As another alternative,
Upon a signal from the controller 160 (
As shown in
As yet another alternative,
The upper magnets 622a, 622b may be any suitable superconductive magnet such as an aluminum nickel cobalt (AlNiCo) magnet. The upper magnets 622a, 622b are shown disposed or embedded within each lift handle feature 212 of the substrate carrier 610 but may also be disposed on a surface of the lift handle features. The upper magnets 622a, 622b are polarized such as to cause an opposing magnetic force against the upper levitation tracks 620a, 620b and lift the substrate carrier 610 upward. The upper levitation tracks 620a, 620b contain coils. The controller 160 (
Similarly, the lower magnets 662a, 662b may be any suitable superconductive magnet such as an AlNiCo magnet. The lower magnets 662a, 662b are shown disposed within opposing bottom corners of the substrate carrier 610, but may be disposed on any opposing surfaces of the substrate carrier 610. The lower magnets 662a, 662b are polarized such as to cause an opposing magnetic force against the lower levitation tracks 660a, 660b when the lower levitation tracks 660a, 660b are energized by the controller 160. Similar to the upper levitation tracks 620a, 620b, successive like poles on the lower levitation tracks 660a and 660b are successively energized by the controller 160 to push the substrate carrier 210 forward through the cleaning tank 125 (and/or the hot/cold rinse tank 126).
When introducing elements of the present disclosure or exemplary aspects or embodiment(s) thereof, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements.
The terms “comprising,” “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims the benefit of U.S. Provisional Patent Application No. 63/629,948, filed Jan. 6, 2023, which was converted to a provisional from the originally filed U.S. patent application Ser. No. 18/150,869, filed Jan. 6, 2023, which is all herein incorporated by reference.
Number | Date | Country | |
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63629948 | Jan 2023 | US |