Substrate hot spot correction for a chemical mechanical polishing processs

Abstract

A method of processing a substrate, includes placing a front surface of a substrate disposed in a carrier head on a polishing surface of a pad. The method further includes delivering a first fluid onto the polishing surface using a first fluid delivery arm. The method further includes determining a location of a hot spot on the front surface. The method further includes determining a rotational orientation of the substrate relative to the carrier head. The method further includes treating the hot spot while polishing the front surface on the polishing surface using a second fluid delivery arm to deliver a second fluid to the polishing surface at a location that will intersect with the hot spot during polishing of the front surface of the substrate.

Description

SUBSTRATE HOT SPOT CORRECTION FOR A CHEMICAL MECHANICALPOLISHING PROCESSSBACKGROUNDField

[0001] The present disclosure relates to chemical mechanical polishing (CMP) of a substrate, such as a semiconductor substrate, and more specifically to treating a hot spot on the substrate during the CMP process.Description of the Related Art

[0002] An integrated circuit is typically formed on a substrate by the sequential deposition of conductive, semiconductive, and / or insulative layers on a semiconductor substrate. A variety of fabrication processes require planarization of a layer on the substrate. For example, one fabrication step involves depositing a filler layer over a non-planar surface and planarizing the filler layer. For certain applications, the filler layer is planarized until the top surface of a patterned layer is exposed. For example, a metal layer can be deposited on a patterned insulative layer to fill trenches and holes in the insulative layer. After planarization, the remaining portions of the metal in the trenches and holes of the patterned layer form vias, plugs, and lines to provide conductive paths between integrated circuits (ICs) on the substrate. As another example, a dielectric layer can be deposited over a patterned conductive layer, and then planarized to enable subsequent photolithographic steps.

[0003] Chemical mechanical polishing (CMP) is one accepted method of planarization. This planarization method typically requires that the substrate be mounted on a carrier head. The exposed surface of the substrate, the surface with the layer deposition, is typically placed against a rotating polishing pad. The carrier head provides a controllable load on the substrate to urge it against the polishing pad. A polishing slurry with abrasive particles is typically supplied to the surface of the polishing pad and spreads in between the substrate and the polishing pad. The polishing pad and the carrier head each rotate at aconstant rotational speed and the abrasive slurry removes material from one or more of the layers.

[0004] Conventional CMP operations, however, cannot determine the rotational orientation of the substrate relative to the carrier head after the substrate is transferred to the polishing pad. As a result, the data obtained from the endpoint sensors cannot be correlated to a known location on the surface of the substrate.

[0005] Additionally, hot spots develop on the front surface of the substrate during the CMP process. The hot spot may be an imperfection in the planarization, such as being a feature on the substrate that has a thickness that is greater than or less than a desired thickness. The location of the hot spot relative to the carrier head is similarly unknown during polishing because the rotational orientation of the substrate relative to the carrier head is unknown. Thus, the hot spot cannot be selectively targeted by a remedial fluid during polishing because the location of the hot spot is unknown. There is a need in the art to determine the rotational orientation of a substrate relative to a carrier head in situ to facilitate targeted treatment of hot spots during of a CMP process.SUMMARY

[0006] In one embodiment, a method of processing a substrate, includes placing a front surface of a substrate disposed in a carrier head on a polishing surface of a pad coupled to a platen. The method further includes delivering a first fluid onto the polishing surface using a first fluid delivery arm. The method further includes determining a location of a hot spot on the front surface. The method further includes determining a rotational orientation of the substrate relative to the carrier head. The method further includes treating the hot spot while polishing the front surface on the polishing surface using a second fluid delivery arm to deliver a second fluid to the polishing surface. The treatment includes determining a first radial position on the polishing surface to pulse a first amount of a second fluid such that the first amount of second fluid will atleast partially pass underneath the hot spot. The treatment further includes pulsing the first amount of the second fluid onto the polishing surface at the first radial position using the second fluid delivery arm.

[0007] In one embodiment, a method of processing a substrate includes polishing a front surface of a substrate on a first pad coupled to a first platen. The method further includes transferring the substrate from the first pad to a second pad coupled to a second platen with a carrier head. The method further includes delivering a first fluid onto a polishing surface of the second pad. The method further includes determining a location of a hot spot on the front surface. The method further includes determining a rotational orientation of the substrate relative to the carrier head. The method further includes treating the hot spot while polishing the front surface on the second pad. The treatment includes determining a first radial position on the polishing surface to pulse a first amount of a second fluid such that the first amount of second fluid will at least partially pass underneath the hot spot. The treatment further includes pulsing the first amount of the second fluid onto the polishing surface at the first radial position.

[0008] In one embodiment, a polishing system includes a polishing station. The polishing station includes a platen including a polishing pad, a carrier head, a first fluid delivery arm, a second fluid delivery arm, an orientation sensor, and a controller. The carrier head is configured to rotate a substrate including a reference mark and a front surface. The first fluid delivery arm is configured to deliver a first fluid onto the polishing pad. The second fluid delivery arm is configured to selectively deliver one or more pulses of a second fluid onto the polishing pad to treat a hot spot on the front surface, wherein the hot spot is located at a known position relative to the reference mark. The orientation sensor is embedded in the platen at the rotational center of the platen, wherein the orientation sensor is configured to scan an edge of a substrate that includes a reference mark. The controller is in communication with the orientation sensor, the pad, the carrier head, and the second fluid delivery arm. The controller is configured to analyze data obtained by the orientation sensor to identify a location of the reference mark relative to the carrier head. Thecontroller is further configured to control a position of the second fluid delivery arm relative to the pad to deliver one or more pulses at one or more radial positions on the pad to treat the hot spot.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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 of the disclosure and are therefore not to be considered limiting of its scope, as the disclosure may admit to other equally effective embodiments.

[0010] Figure 1 depicts a schematic top view of an exemplary chemical mechanical polishing (CMP) system.

[0011] Figure 2A depicts a schematic sectional view of an exemplary polishing station of the CMP system from Figure 1 according to embodiments described herein.

[0012] Figure 2B is a top view of a front surface of a substrate polished on the polishing station of Figure 2A according to embodiments described herein.

[0013] Figure 3A depicts a schematic top view of the carrier head positioned at a scan position on the polishing pad from the polishing station of Figure 2A according to embodiments described herein.

[0014] Figure 3B depicts a top view of a front surface of a substrate scanned by an orientation sensor of the polishing station of Figure 2A according to embodiments described herein.

[0015] Figure 4 depicts an exemplary signal obtained by an orientation sensor of the polishing station of Figure 2A according to embodiments described herein.

[0016] Figure 5 depicts a top view of a front surface of a substrate showing the scan paths of endpoint sensors of the polishing station of Figure 2A according to embodiments described herein.

[0017] Figure 6 illustrates a graph of an example trace obtained by an endpoint sensor during a CMP process.

[0018] Figure 7A depicts a schematic top view of the polishing pad from the polishing station of Figure 2A with a first amount of second fluid deposited at a first radial position on the polishing pad, according to embodiments described herein.

[0019] Figure 7B depicts the schematic top view of the polishing pad shown in Figure 7A showing the first amount of the second fluid treating a hot spot on a substrate, according to embodiments described herein.

[0020] Figure 8A is a schematic top view of portion of a polishing station illustrating a carrier head on a polishing pad with a first amount of a second fluid disposed on the polishing pad at a first radial position, according to embodiments described herein.

[0021] Figure 8B is a schematic top view of the portion of the polishing station of Figure 8A that shows the first amount of the second fluid disposed under a hot spot of a substrate, according to embodiments described herein.

[0022] Figure 8C is a schematic top view of the portion of the polishing station of Figure 8A that shows a second amount of the second fluid disposed on the polishing pad at a second radial position, according to embodiments described herein.

[0023] Figure 9 is a flowchart of a method of processing a substrate according to embodiments described herein.

[0024] Figure 10 is a flowchart of a method of processing a substrate according to embodiments described herein.

[0025] 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.DETAILED DESCRIPTION

[0026] An apparatus and methods for a targeted treatment of a hot spot on a substrate during a chemical mechanical polishing (CMP) process is disclosed herein. The rotational orientation of the substrate and the location of the hot spot thereon is obtained to facilitate the targeting of the hot spot. The rotational orientation of the substrate may be obtained in-situ. The known rotational orientation of the substrate, and the location of the hot spot disposed thereon, is used to selectively treat the hot spot by delivering a fluid to a polishing pad at a position that will pass underneath the hot spot during the CMP process. The fluid may change a polishing characteristic, such as increasing or decreasing the polishing rate, to treat the hot spot and area around the hot spot while other areas of the substrate continue to polish without a change in the polishing characteristic.

[0027] Figure 1 is a top plan view illustrating one embodiment of a CMP system 100. The CMP system 100 includes a factory interface module 102, a cleaner 104, a polishing module 106, and a controller 190. A substrate 115, such as a silicon wafer with one or more layers deposited thereon, is processed within the CMP system 100 to polish a front surface of the substrate 115.

[0028] A wet robot 108 is provided to transfer the substrates 115 between the factory interface module 102 and the polishing module 106. The wet robot 108 may also be configured to transfer the substrates 115 between the polishing module 106 and the cleaner 104. The factory interface module 102 includes a dry robot 110 which is configured to transfer the substrates 115 between one or more cassettes 114, one or more transfer platforms 116, one or more metrology stations 117, and one or more pre-aligner stations 118 of the factory interface 102. Substrates 115 are loaded into the CMP system 100 viathe cassettes 114. In one embodiment depicted in Figure 1 , four substrate storage cassettes 114 are shown. The dry robot 110 within the factory interface 102 has sufficient range of motion to facilitate transfer between the four cassettes 114 and the one or more transfer platforms 116. Optionally, the dry robot 110 may be mounted on a rail or track 112 to position the robot 110 laterally within the factory interface module 102. The dry robot 110 additionally is configured to receive the substrates 115 from the cleaner 104 and return the clean polished substrates to the substrate storage cassettes 114.

[0029] Figure 1 shows an exemplary polishing module 106 that includes a plurality of polishing stations 124 on which the substrates 115 are polished while being retained in a carrier head 210 (e.g., polishing head). Each polishing station 124 includes a conditioning assembly 132, a first fluid delivery arm 135 (e.g., a polishing fluid delivery module), and a second fluid delivery arm 160 (e.g., a hot spot treatment module). While the polishing module 106 is shown having three polishing stations 124, the polishing module 106 may have more than three polishing stations 124. For example, the polishing module 106 may have a two pairs of polishing stations 124, each pair of stations 124 processing a substrate 115 independently of the other pair. The polishing stations 124 are sized to interface with one or more carrier heads 210 to facilitate polishing the substrate 115. The carrier heads 210 are coupled to a carriage (not shown) that is mounted to an overhead track 128 that is shown in phantom in Figure 1. The overhead track 128 allows the carriage to be selectively positioned around the polishing module 106 which facilitates positioning of the carrier heads 210 selectively over the polishing stations 124 and a load cup 122. In the embodiment depicted in Figure 1 , the overhead track 128 has a circular configuration which allows the carriages retaining the carrier heads 210 to be selectively and independently rotated over and / or clear of the load cups 122 and the polishing stations 124. Additionally, the overhead tracks 128 facilitate the carriage sweeping the rotating carrier heads 210 relative to a polishing station 124 during polishing. The polishing stations 124 will be described in greater detail in relation to Figure 2A.

[0030] Each polishing station 124 includes a polishing pad 204 having a polishing surface (e.g., a polishing surface 204A in Figure 2A) capable of polishing a substrate 115. The polishing pad 204 is supported on a platen (e.g., a platen 202 in Figure 2A) which rotates the polishing pad 204 during processing. Different polishing pads 204 may be used at different polishing stations 124 to control the material removal of the substrate 115.

[0031] Each polishing station 124 may include the conditioning assembly 132. In one embodiment, the conditioning assembly 132 may comprise a pad conditioning assembly 140 which dresses the polishing surface of the polishing pad 204 by removing polishing debris and opening the pores of the polishing pad 204 by use of a pad condition disk 133.

[0032] Each polishing station 124 includes a first fluid delivery arm 135. The first fluid delivery arm 135 may comprise a first arm 134 to deliver a first fluid (e.g., first fluid 222 in Figure 2A), to the polishing pad 204, such as a slurry. The first fluid disperses over the polishing surface 204A of the polishing pad 204 to facilitate polishing. The first fluid may be one or more fluids to interact with the front surface of the substrate 115 during polishing. The one or more first fluids may be delivered to the first fluid delivery arm 135 by a fluid source 182. The one or more first fluids may be a polishing fluid and / or a relatively high pressure stream of a cleaner fluid, e.g., deionized water. One example of a first fluid can include a polishing fluid that includes, but is not limited to one or more surfactants, one or more chelating agents, one or more oxidizers, one or more corrosion inhibitors, one or more polar solvents, and deionized water. The composition may also further include one or more pH adjusting agents and / or abrasive particles. Abrasive particles which may be used in CMP compositions include, but are not limited to, alumina (AI2O3), silica (SiC>2), titania (TiC ), or ceria (CeC ) particles, or any other abrasives known in the art and used in conventional CMP compositions.

[0033] One or more of the polishing stations 124 includes a second fluid delivery arm 160 to treat a hot spot on the front surface of the substrate 115. Hot spots can develop on patterned substrates and non-patterned substrates.A hot spot may appear during a polishing process and generally develops near the edge of the front surface of the substrate 115. The hot spot may be a continuous feature (see hot spot 280 in Figure 2B) or a plurality of discontinuous features on the front surface of the substrate 115 with a thickness that deviates from the desired thickness or the thickness present across a majority of the substrate. The hot spot may be the result of a deviation of the composition of the polishing fluid, such as the first fluid, deviation in the friction of the polishing pad 204, and / or a deviation in the pressure applied to the back of the substrate 115 by a diaphragm (e.g., diaphragm 212). In some embodiments, the hot spot may be a buildup of residue on the front surface of the substrate 115. For example, the hot spot may be one or more features where the material on the front surface of the substrate 115 is thicker or thinner than desired, such as being thicker or thinner than a majority of the surface of the substrate 115.

[0034] The second fluid delivery arm 160 may comprise a second arm 162 to selectively deliver a second fluid at a radial position on the polishing surface 204A of the pad 204 that will be rotated underneath (e.g. , intersect with) the hot spot on the substrate 115 being polished on the pad 204. The second fluid may be delivered treat the hot spot by adjusting a polishing characteristic, such as the polishing rate (e.g., removal rate), of a treatment region on the polishing surface 204A. The second fluid may be repeatedly delivered, such as by pulsing, to target a targeted area on the front surface of the substrate 115 that includes the hot spot during polishing. The targeted area is the portion of the front surface that includes the hot spot and also includes the area immediately around the hot spot in some embodiments. Each application of the second fluid, such as each pulse, can be delivered onto the polishing surface 204A at a different radial position to accommodate the movement of the carrier head 210 and the location of the hot spot relative to the carrier head 210 during the polishing process. The composition of the second fluid may change each time the second fluid is delivered to the polishing pad 204 to increase or decrease the polishing rate experienced by the hot spot. The treatment may continue until the hot spot is removed or substantially removed.

[0035] The first fluid is already present at the location where the second fluid is deposited. The second fluid may mix with, displace, dilute, and / or interact with the first fluid when the second fluid is delivered onto the polishing surface 204A. However, the second fluid second fluid is delivered in an amount at the radial position (e.g., radial location) on the polishing surface 204A to target the hot spot rather than the entire surface of the substrate 115. The second fluid does not cover the polishing surface 204A to the same extent as the first fluid, and is instead generally limited to a treatment region that passes underneath the hot spot and area of the front surface surrounding the hot spot as the pad 204 rotates. Thus, the second fluid may not change or substantially change the polishing rate facilitated by the first fluid outside of the treatment region. In other words, the remainder of the front surface of the substrate 115 that does not interact with the treatment region may continue polishing at the same or substantially the same rate as before the introduction of the second fluid. Therefore, the targeted area of the substrate 115 that includes the hot spot may be polished at a different rate than the non-targeted area of the substrate 115.

[0036] The second fluid may be one or more fluids, such a polishing fluid, various chemical components, and / or deionized water. The various chemical components can include, but are not limited to one or more surfactants, one or more chelating agents, one or more oxidizers, one or more corrosion inhibitors, one or more polar solvents, and one or more pH adjusting agents. For example, the polishing fluid delivered by the second fluid delivery arm 160 may be more abrasive than the polishing fluid delivered by the first fluid delivery arm 135 to increase the rate of polishing on a treatment region of the polishing surface 204A to treat the hot spot. For example, the second fluid may be deionized water to dilute the first fluid at the treatment region to reduce the polishing rate to treat the hot spot.

[0037] Each polishing station 124 shown in Figure 1A includes the second fluid delivery arm 160. In some embodiments, only one of the polishing stations 124 includes the second fluid delivery arm 160, such as the second polishing station 124.

[0038] In some embodiments, the substrate processing station 124 may include more than one second fluid delivery arm 160. Each second fluid delivery arm 160 may deliver the second fluid to the same or different radial position on the polishing surface 204A. Each second fluid delivery arm 160 may be independently controlled and operated by the controller 190.

[0039] At least one load cup 122, such as the two load cups 122 shown in Figure 1 , is near the lower right corner of the polishing module 106 between the polishing stations 124 closest to the wet robot 108. The load cups 122 may serve multiple functions, including washing the carrier head 210, receiving the substrate 115 from the wet robot 108, washing the substrate 115, and loading the substrate 115 into the carrier heads (e.g., a carrier head 210 in Figure 2).

[0040] The substrate 115 will typically have a reference mark, such as a notch, flat edge, or other type of feature that can be used to identify crystalline orientations of the substrate 115 and note a rotational orientation of a front surface of the substrate 115 relative to a central axis. In certain embodiments, the factory interface module 102 can also include a pre-aligner 118 to position the substrate 115 in a known and desirable rotational orientation. The prealignment of the substrate 115 to a desired rotational orientation allows the substrate 115 to be transferred to the load cup 122 having a known rotational orientation. Thus, the carrier head 210 is able to retrieve the substrate 115 at a known rotational orientation relative to the carrier head 210. For example, the pre-aligner 118 may include a reference mark detection system, such as an optical interrupter sensor (not shown), to sense when the reference mark is at a specific angular position.

[0041] In certain embodiments, the substrate 115 is placed in the metrology station 117 by the dry robot 110 prior to placing the substrate 115 on the transfer platform 116. For example, the dry robot 110 may transfer the substrate 115 from the pre-aligner 118 to the metrology station 117. The metrology station 117 is used to measures various aspects of the substrate 115. The metrology station 117 can be used to identify the location of one or more hot spots on the surface of the substrate 115 in relation to the reference mark. The metrologystation 117 may use an optical, eddy current, resistive, or other sensors to measure the substrate 115. For example, the metrology station 117 may measure a thickness of the upper layer on the patterned surface of the substrate 115. The controller 190 receives the measurements which may be used to facilitate processing the substrate 115 within the CMP system 100. The dry robot 110 may transfer the substrate 115 to the transfer platform 116 after the substrate 115 is measured in the metrology station 117.

[0042] The wet robot 108 is configured to transfer the substrate 115 from the transfer platform 116 to one of the load cups 122. A rinsed-clean carrier head 210 is moved above the load cup 122 with the unpolished substrate 115. The unpolished substrate 115 is thereafter chucked to the carrier head 210, which then moves to a position above the pad 204 of a polishing station 124 to begin the CMP process.

[0043] The controller 190 controls aspects of the CMP system 100 during a CMP process (e.g., polishing process, polishing operation, polishing). In certain embodiments, the controller 190 is one or more programmable digital computers executing digital control software. The controller 190 can include a CPU (e.g., processor) 191 situated near the polishing apparatus, e.g., a programmable computer, such as a personal computer. The controller can include a memory 192 and support circuits 193. The controller 190 can, for example, coordinate rotation of the polishing pad 204 and the carrier head 210, as well as the position of the carrier head 210 along a sweep path, to perform the desired CMP process and to facilitate monitoring for the endpoint of the CMP process. Additionally, the controller 190 can coordinate the delivery and location of delivery of the second fluid, the rotation of the polishing pad 204 and the carrier head 210, and the position of the position of the carrier head 210 along the sweep path to treat a hot spot and to monitor the hot spot treatment. For example the controller 190 can coordinate the rotational rate of the carrier head 210, position of the carrier head 210 along the sweep path, and the rotational rate of the platen 202 to cause the second fluid delivered onto the polishing pad 204 to intersect with the hot spot. The CMP process system 100is powered by power source 180, such as an electric power source configured to supply electric power to the components of the CMP process system 100.

[0044] The platen 202 and the carrier head 210 each have a rotation sensor such as an encoder, to determine their rotational position during the CMP operation. As shown in Figure 1 , a platen encoder 195, a first head encoder 196, and a second head encoder 197 are integrated into the controller 190. The platen encoder 195 is configured to determine the rotational (e.g., angular) orientation of the platen 202 and the pad 204. The first head encoder 196 is configured to determine the rotational orientation of each carrier head 210. The second head encoder 197 is configured to determine the location of each carrier head 210 above the polishing pad 204 (e.g., along the sweep path 302 of the carrier head 210 in Figure 3A). Thus, the controller 190 is able to determine and track the rotational orientation of the carrier head 210 with respect to the platen 202 during the CMP process. In some embodiments, each carrier head 210 has its own dedicated first and second head encoders 196, 197. In further embodiments, the controller 190 may calculate a rotation rate of the carrier head 210 and / or platen 202 and polishing pad 204 using the encoder and an internal timing element.

[0045] The controller 190 also includes a hot spot encoder 198. The hot spot encoder 198 tracks the location of the hot spot relative to the reference mark of the substrate 115. The hot spot encoder 198 may receive the location of the hot spot relative to the reference mark from the metrology station 117. In some embodiments, the location of the hot spot relative to the reference mark may be obtained by one or more end point sensors (e.g., metrology sensors) disposed in the pad 204. The controller 190 can correlate the location of the hot spot relative to the reference mark with the rotational orientation of the substrate to determine the position of the hot spot with respect to the carrier head 210.

[0046] The controller 190 is able to determine the location of the hot spot on the pad 204 based on the information from the platen encoder 195, the first head encoder 196, the second head encoder 197, and the hot spot encoder198. The controller 190 can control the rotational rate of the carrier head 210, the platen 202, and the position of the carrier head 210 along a sweep path (see sweep path 302) to pass the hot spot over a treatment region of the polishing surface 204A covered in the second fluid. Additionally, the controller 190 can use the rotational rate of the carrier head 210, the rotational rate of the platen 202, and the movement of the carrier head 210 along the sweep path to calculate a radial delivery point on the polishing surface 204A for the second fluid such that the second fluid will intersect with the hot spot. In other words, the second fluid deposited at the radial position on the polishing surface 204A such that the second fluid is able to pass underneath, and thus interact with, the hot spot as the carrier head 210 and platen 202 move during polishing. In some embodiments, the controller 190 can control the rotational speed and position of the carrier head 210 and the rotational speed of the pad 204 to intersect the hot spot with the second fluid deposited onto the polishing surface at the radial position.

[0047] The substrate 115 may be polished in one or more of the polishing stations 124. For example, a carrier head 210 may retrieve an unpolished substrate 115 from a load cup 122. The carrier head 210 and substrate 115 chucked thereto are then moved to a first polishing station 124, such as the polishing station 124 in the upper right corner of the polishing module 106 closest to the cleaner 104. The substrate 115 is then subjected to a CMP polishing operation on the first polishing station 124, such as removing a first layer formed on the substrate 115. Once the substrate 115 is done polishing in the first polishing station 124, then the carrier head 210 moves the substrate 115 to a second polishing station 124 (e.g., the polishing station 124 in the upper left corner of the polishing module 106) for additional CMP polishing. For example, the second polishing station 124 may polish the surface of the substrate 115 to form trench lines of a desired height. In some embodiments, the carrier head 210 and substrate 115 may optionally be transferred from the second polishing station 124 to a third polishing station 124 (e.g., the polishing station 124 in the lower left corner of the polishing module 106) to subject thesubstrate 115 to additional polishing. A hot spot can be treated in one or more of the polishing stations 124 during polishing.

[0048] After polishing, the carrier head 210 moves the polished substrate 115 chucked thereto above a load cup 122 where the polished substrate 115 is thereafter placed into the load cup 122. The wet robot 108 transports the polished substrate 115 from the load cup 122 to a cleaning chamber in the cleaner 104, where slurry residues and other contaminants that have accumulated on the substrate’s 115 surface during polishing are removed. In the embodiment depicted in Figure 1 , the cleaner 104 includes two pre-clean modules 144, two megasonic cleaner modules 146, two brush box modules 148, two spray jet modules 150, and two dryers 152. The dry robot 110 then removes the substrate 115 from the cleaner 104. In some embodiments, the dry robot 110 transfers the substrate 115 to the metrology station 117 to be measured again. In certain embodiments, the post-polish measurements can be used to adjust the polishing process parameters for a subsequent substrate. Finally, the dry robot 110 returns the substrate 115 to one of the cassettes 114.

[0049] Figure 2A illustrates a schematic cross-sectional view of a polishing station 124 of the CMP system 100 of Figure 1 . As shown, the polishing station 124 further includes a plurality of endpoint sensors 224 and an orientation sensor 250. A substrate 115 disposed in the carrier head 210 is shown engaged with the polishing surface 204A of the pad 204 that is coupled to the platen 202.

[0050] Figure 2B is a top view of the substrate 115 to illustrate the front surface 230 of the substrate 115 that is engaged with the polishing pad 204 during polishing. The front surface 230 includes a patterned portion 232 and a non-patterned portion 234. The patterned portion 232 (e.g., patterned surface) is the portion of the substrate 115 were a plurality semiconductor devices are formed during one or more processes. As shown, the patterned portion 232 is divided into a plurality of full dies 233 arranged in a grid-pattern. Each die 233 is a particular semiconductor device being formed on the substrate 115. For example, the semiconductor devices include one or more layers formed by fromone or more processes, such as through physical vapor deposition (PVD) or atomic layer deposition (ALD).

[0051] The non-patterned portion 234 is the portion of the front surface 230 around the patterned portion 232. Semiconductor devices are not formed on the non-patterned surface 234. The non-patterned portion 234 may be exposed to the same processing environments that forms the patterned portion 232. Materials, such as barrier metals, may be deposited on the non-patterned surface 234 while the semiconductor devices are formed on the patterned portion 232. In some embodiments, the non-patterned portion 234 may be a partially patterned portion that includes only partial, and not full, dies. The surface area of the non-patterned portion 234 may not be uniform around the patterned portion 232. As shown in Figure 2B, the surface area of the nonpatterned surface 234 fluctuates around the patterned portion 232 depending on the shape of the patterned portion 232. Thus, there are portions of the nonpatterned surface 234 with a surface area greater than other portions.

[0052] The substrate 115 includes a reference mark 236 at the edge of the substrate 115 and thus at the edge of the non-patterned portion 234. The reference mark 236 is a fixed feature formed on the substrate 115 depending on the doping type and crystalline orientation of the substrate 115. While the reference mark 236 is shown as a v-shaped notch formed on the edge of the substrate 115 in Figure 2B, the reference mark 236 may be another feature. For example, the reference mark 236 may be one or more flat edges of the substrate 115.

[0053] The substrate 115 has a first line of symmetry 235 that passes through the center of the reference mark 236. The non-patterned surface 234 is generally symmetrical about this first line of symmetry 235. Thus, there is a first region 237 on either side of the line of symmetry 235 adjacent to the reference mark 236 that has substantially the same surface area. Additionally, there is a similar pair of second regions 238 on the opposite edge of the substrate 115 as the reference mark 236 that has a similar surface area as the first region 237. While the non-patterned surface 234 may be generallysymmetric about the first line of symmetry 235, the circuits formed in the individual dies 233 of the patterned surface 232 may or may not be symmetric about this first line of symmetry 235.

[0054] Additionally, a hot spot 280 is shown in dashed on the front surface 230 near the edge of the substrate 115. The hot spot 280 is shown as one continuous and irregularly shaped feature. However, the hot spot 280 may be a region (e.g., area) of the front surface 230 that includes a plurality of discontinuous features. The hot spot 280 may extend over part of the patterned surface 232 and non-patterned surfaced 234 as shown in Figure 2B. In some embodiments, the hot spot 280 may be located on the patterned surface 232. The hot spot 280 is a featured formed on the front surface 230 and thus has a fixed location relative to the reference mark 236.

[0055] Referring back to Figure 2A, the polishing pad 204 is secured to the platen 202, such as being secured using an adhesive, such as a pressure sensitive adhesive (PSA) layer (not shown), disposed between the polishing pad 204 and the platen 202. The carrier head 210, facing the platen 202 and the polishing pad 204 mounted thereon, includes a flexible diaphragm 212 configured to impose different pressures against a backside surface of a substrate 115 that is disposed between the carrier head 210 and the polishing pad 204. This flexible diaphragm 212 is also configured to chuck the substrate 115 to the carrier head 210 to allow the carrier head 210 to move the substrate 115 around the polishing module 106. The carrier head 210 includes a carrier ring 218 surrounding the substrate 115 which holds the substrate 115 within the carrier head 210 during polishing. The carrier head 210 rotates about a carrier head axis 216 while the flexible diaphragm 212 urges the front surface 230 (Figure 2B) of the substrate 115 against the polishing surface 204A of the polishing pad 204. During polishing, a downforce on the carrier ring 218 urges the carrier ring 218 against the polishing pad 204 to improve the polishing process uniformity and prevent the substrate 115 from slipping out from under the carrier head 210. In certain embodiments, the carrier head 210 includes a shaft 211 which has an axis that is collinear with carrier head axis 216. In furtherembodiments, the platen 202 and the carrier head 210 each have a mechanism or motor (not shown) driving their rotation.

[0056] In some embodiments, the platen 202 and polishing pad 204 both rotate about a common platen axis 205. In some embodiments, the polishing pad 204 rotates in the same rotational direction as the rotation direction of the carrier head 210. For example, the polishing pad 204 and carrier head 210 both rotate in a counter-clockwise direction. The polishing pad 204 and carrier head 210 may be rotated at the same or different speed during a polishing operation. As shown in Figure 2A, the polishing pad 204 has a surface area that is greater than the front surface 230 of the substrate 115. However, in further embodiments, the polishing pad 204 has a surface area that is less than the surface area of the front surface 230 of the substrate 115.

[0057] Referring to Figure 2A, the second fluid delivery arm 160 includes the second arm 162, a fluid delivery head 261 , and actuator 264. The actuator 264 enables the second arm 162 to rotate about the axis 263. The second arm 162 is coupled to the actuator 264 at a first distal end. The fluid delivery head 261 is disposed on the opposite end of the second arm 162, such that the fluid delivery head 261 is disposed on a second distal end of the second arm 162. The second arm 162 may be an extendible arm, such that the length of the second arm 162 may be selectively changed to adjust the position of the fluid delivery head 261 relative to the pad 204.

[0058] The second fluid delivery arm 160 is also disposed over the polishing pad 204 and in some configurations is disposed on an opposite side of the platen 202 from the first fluid delivery arm 135. In one embodiment, the second fluid delivery arm 160 and the first fluid delivery arm 135 are disposed over opposite quadrants or halves (as shown in Figure 1 ) of the polishing pad 204. The first fluid delivery arm 135 delivers the first fluid 222 onto the polishing pad 204 at a first radial position on the polishing pad 204. The second fluid delivery arm 160 dispenses a second fluid 262, such as a polishing fluid and / or a water, onto the polishing pad 204. The second fluid 262 is dispensed onto the polishing pad 204 at a second radial position. In some embodiments, thesecond fluid 262 is mixed with the first fluid 222 to adjust the amount of the polishing fluids and composition of the polishing fluids. In some embodiments, the mixture of the first fluid 222 and the second fluid 262 will either increase or reduce the concentration of one or more constituents of the first fluid 222 in the treatment region on the polishing surface 204A. In one example, the one or more constituents of the first fluid 222 that may be adjusted by the addition of the second fluid 262 includes the amount of and / or concentration of abrasive particles (e.g., silica-based abrasive, ceria-based abrasive, and alumina-based abrasive), water or other chemical solutions (e.g., acids, bases, inhibitors, etc.).

[0059] The second fluid delivery arm 160 is moveable about axis 263. The second arm 162 rotates about the axis 263 to change the position of the fluid delivery head 261 over the polishing pad 204. In some embodiments, the second arm 162 is rotatable between 5 and 180 degrees about the axis 263. The second arm 162 can be moved to and from a retracted position and an extended position and to one or more positions between the extended and retracted positions. The second arm 162 is moveable relative to the polishing pad 204 to allow for second radial position to be adjusted throughout the process, such as to compensate for a shrinking area of the hot spot during polishing or the position of the carrier head 210 when desired to deliver the second fluid. In some embodiments, the movement of the second arm 162 may be synchronized with the movement of the carrier head 210 to repeatedly deposit the second fluid at a position relative to the carrier head 210 that will interact with the targeted area of the substrate 115.

[0060] The fluid delivery head 261 is pointed downwards towards the polishing pad 204. The fluid delivery head 261 is configured to provide one or more second fluids 262, such as either a polishing fluid, various chemical components, additives and / or water onto the polishing pad 204. The fluid delivery head 261 may include one or more nozzles or openings to deliver the one or more second fluids 262 onto the polishing surface 204A. In some embodiments, the fluid delivery head 261 may include one or more of, or a combination of, a single stream dispense nozzle, spray gun nozzle, a flat fanjet spray nozzle, an atomizing nozzle or megasonic nozzle. In some embodiments, each nozzle may deliver a different fluid to polishing pad 204, such as a fluid having a different composition than other fluids. For example, one nozzle may deliver deionized water while another delivers a chemical additive. The fluid delivery head 261 may be operated such that each nozzle delivers fluid at the same time or in a sequence. For example, each nozzle may be operated such that multiple different fluids are pulsed onto the polishing pad 204 simultaneously. In some embodiments, deionized water, a chemical solution, and polishing fluid may be delivered simultaneously or separately from the fluid delivery head 261. In some embodiments, the one or more second fluids 262 may be delivered onto the pad 204 at the second radial position as a pulse of fluid flow over a time period to deliver the desired amount of fluid to treat the targeted area of the substrate 115.

[0061] The fluid source 182 supplies fluids to the first fluid delivery arm 135 and the second fluid delivery arm 160. In some embodiments, a temperature control unit 272 is fluidly connected to the second arm 162. The temperature control unit 272 and fluid source 182 are connected to and controlled by the controller 190. The fluid source 182 supplies one or more second fluids 262 to the fluid delivery head 261 to be dispensed onto the polishing pad 204. The fluid source 182 includes one or more fluid sources that are configured to provide the one or more second fluids 262. The sources of the one or more second fluids 262 provided from the fluid source 182 are each configured to provide their respective fluids at a desired flow rate and pressure. The polishing fluid source may provide one or more fluids that include a chemical solution (e.g., acid, base, inhibitor, etc.) and / or slurry containing solution (e.g., abrasive particle (e.g., silica, ceria, or alumina based abrasives) containing solution) used for substrate polishing. The second fluid 262 may also include a polishing rate promoter such as H2O2. The water source can be a de-ionized water source. The second fluid 262 may also be a polishing rate inhibitor, for example benzotriazole (BTA). The fluid source may also be any typical post CMP cleaning chemical, for example, PlanarClean® and / or PL6502.

[0062] The fluid source 182 may include a pump or a plurality of pumps (one for each fluid). The fluid source 182 is fluidly connected to the temperature control unit 272 by a first conduit 271 . In some embodiments, the temperature control unit 272 may be integrated into the fluid source 182 and the first conduit 271 is removed. The temperature control unit 272 controls the temperature of the one or more second fluids 262 being delivered to the second fluid delivery arm 160 and the fluid delivery head 261 through the second conduit 274. The temperature control unit 272 may include resistive heating elements therein for heating of the fluids disposed therein. The temperature control unit 272 may also include cooling channels disposed therein for cooling the fluids or for cooling the heating elements. The temperature control unit 272 may heat or cool the fluids to temperatures suitable to enhance or inhibit the CMP polishing process. It is believed that by controlling the temperature of the fluids supplied to the targeted area of the substrate 115 during a polishing process, along with the other CMP process control variables discussed herein (e.g., amount of a fluid, concentration of fluid components, applied pressure, etc.), the chemical activity and / or interaction of the abrasive particles with the surface of the substrate can be adjusted to adjust the removal rate in the targeted area of the substrate 115 versus other regions of the substrate. In one example, the temperature of the one or more second fluids supplied to the polishing pad, and thus the targeted area of the substrate 115 during a portion of a polishing process, is controlled to a temperature that is less than the temperature of the first fluid and polishing surface 204A during a polishing process to reduce the chemical activity of the combined fluids, and also in some cases alter the properties of the polishing pad 204 material. In some embodiments, the temperature control unit 272 is disposed external from the second fluid delivery arm 160 to reduce the volume occupied by the second fluid delivery arm 160 and reduce the impact of the heating or cooling on the volume surrounding the second fluid delivery arm 160.

[0063] Figure 2A also shows an exemplary embodiment of one of the endpoint sensors 224 (e.g., metrology sensors). Each endpoint sensor 224 is positioned radially from the platen axis 205. The endpoint sensor 224 isdisposed in a platen opening 226 formed in the platen 202 and beneath an optically transparent feature 227 (e.g., window) of the polishing pad 204. The endpoint sensor 224 directs light through the platen opening 226 and window 227 at the front surface 230 of the substrate 115 to detect properties of the front surface 230 as the endpoint sensor 224 passes beneath the substrate 115 during polishing. For example, the controller 190 may use the data collected by the endpoint sensors 224 to determine when the endpoint of the CMP process is reached. The endpoint may be, for example, when a desired thickness of a layer formed on the patterned surface 232 is reached. In some embodiments, the endpoint may be reached when the metal in a plurality of trench lines formed on the patterned portion 232 reaches a desired thickness.

[0064] While the endpoint sensor 224 is shown as an optical sensor, the endpoint sensor 224 may be any other suitable sensor capable of monitoring changes in the patterned portion 232 during the CMP process. For example, the endpoint sensor 224 may be an eddy current sensor or an inductive current sensor. The eddy current sensor and inductive current sensor may be embedded in the platen 202 and / or pad 204, and the transparent features 227 and opening 226 may be omitted. While the polishing station 124 is shown having three endpoint sensors 224 disposed around the orientation sensor 250, as evidenced by the three transparent features 227 in Figure 1 , the polishing station 124 may include less than or more than three endpoint sensors 224.

[0065] Each endpoint sensor 224 is positioned at a fixed distance from the rotational center (e.g., platen axis 205) of the platen 202. The platen encoder 195 (Figure 1 ) tracks the rotational position of the platen 202 and pad 204. The controller 190 (Figure 1 ) is able to determine the location of the endpoint sensor 224 as the platen 202 rotates based on the fixed location of the endpoint sensor 224 and the rotational information obtained from the platen encoder 195.

[0066] The endpoint sensor 224 may also be used to measure the thickness of the substrate 115, including the substrate edge, and determine a removal rate across the front surface 230 of the substrate 115 and the substrate edge during polishing. In some embodiments, the process of dispensing of the oneor more second fluid from the second fluid delivery arm 160 is then controllable based upon the measured removal rate by the endpoint sensor 224.

[0067] In some embodiments, the one or more endpoint sensors 224 may be used to monitor polishing of one or more hot spots on the front surface of the substrate 115, such as periodically measuring the thickness of the hot spot. For example, the thickness of the hot spot may be compared to the desired thickness of the material on the substrate 115. The controller 190 may instruct the second fluid delivery arm to 160 to periodically deliver the second fluid 262 to treat the hot spot until the endpoint sensors 224 detect that the hot spot is removed or substantially removed. In some embodiments, the endpoint sensors 224 are used to monitor changes in the polishing rate of the hot spot. The amount or composition of the second fluid may be selectively adjusted to increase or decrease the polishing rate in response to changes in the hot spot, such as changes in the polishing rate of the hot spot, detected by the endpoint sensors 224.

[0068] In some embodiments, the endpoint sensor 224 may be used to identify one or more hot spots on the surface of the substrate 115. For example, the plurality of endpoint sensors 224 may be used to identify the thickness of the material across the front surface 230. The hot spot may be identified based on a thickness of the front surface that is less than or greater than a threshold value. In some embodiments, the thickness data obtained by the endpoint sensors 224 is used to generate a heat map showing differences in the thickness of the material across the front surface 230. The hot spot may is identified based on the heat map. The heat map may be analyzed by the controller 190 or an operator to identify the location of the hot spot.

[0069] Figure 2A also shows the orientation sensor 250. As will be discussed in relation to Figures 3A and 3B, the orientation sensor 250 is used to locate the reference mark 236 in-situ so that the controller 190 can determine the rotational orientation of the substrate 115 relative to the carrier head 210 and the pad 204. The controller 190 is able to correlate the ascertained location of the reference mark 236 with respect to the rotational orientation of the carrierhead 210 since the substrate 115 is rotating with the carrier head 210. The orientation sensor 250 is used to ascertain the substrate’s 115 rotational orientation after the substrate 115 is transferred to a polishing station 124 from a different polishing station 124. In other words, the substrate 115 does not have to be removed from the polishing module 106, passed through the cleaner 104, and placed into the pre-aligner 118 or metrology station 117 to ascertain the rotational orientation of the substrate 115 prior to polishing substrate 115 on a second or third polishing station 124. Similarly, the location of a hot spot with respect to the rotational orientation of the substrate 115 may be ascertained without placing the substrate 115 into the metrology station 117 prior to moving the substrate 115 to the second or third polishing station 124.

[0070] Knowing the rotational orientation of the substrate 115 and carrier head 210 and the location of each endpoint sensor 224 during polishing allows the controller 190 to ascertain which part of the front surface 230 of the substrate 115 is being scanned by a particular endpoint sensor 224. In other words, the controller 190 can correlate the position and orientation of the substrate 115 with the position of each endpoint sensor 224 during the polishing process. This allows the controller 190 to monitor the polishing of specific areas of the surface of the substrate 115, such as monitoring the removal of a hot spot 280. Additionally, this allows the endpoint sensors 224 to determine the location of a hot spot with respect to a known rotational orientation of the substrate 115.

[0071] The orientation sensor 250 is located at the rotational center of the platen 202 such that the rotational axis of the sensor 250 is collinear with the platen axis 205. The endpoint sensors 224 are arranged around the orientation sensor 250 and orbit around the platen axis 205 as the platen 202 rotates. To find the reference mark 236, the carrier head 210 is moved to a scan position as shown in Figure 2A (see also Figure 3A) to place the edge of the substrate 115 above the orientation sensor 250. This allows the orientation sensor 250 to scan the edge of the substrate 115 to locate the reference mark 236. In some embodiments, the orientation sensor 250 scans the edge of the substrate115 as the carrier head 210 makes one or more complete revolutions around the carrier head axis 216 in order to find the reference mark 236. In other embodiments, the reference mark 236 is located after only a partial revolution of the carrier head 210.

[0072] In some embodiments, and as shown in Figure 2A, the orientation sensor 250 is an isotropic electromagnetic sensor. In some embodiments, the orientation sensor 250 is an eddy current sensor, an optical sensor, or other sensor capable of detecting the reference mark 236. As shown, the orientation sensor 250 is partially embedded in both the platen 202 and the pad 204. In some embodiments, the orientation sensor 250 is only embedded in the platen 202 and is covered by the pad 204.

[0073] In some embodiments, a layer partially or fully covers the front surface 230, with both the patterned portion 232 and non-patterned portion 234 being fully or partially covered by the layer. The hot spot 280 may be formed on this layer. This layer may be deposited to form another layer or feature on the dies 233 of the patterned portion 232 that will be polished down in the CMP system. The orientation sensor 250 is still able to scan the edge of the substrate 115 to locate the reference mark 236 even if a layer is deposited over both the patterned portion 232 and the non-patterned portion 234. For example, the orientation sensor 250 may obtain data that shows the part of the layer scanned by the orientation sensor 250 was over the underlying patterned portion 232 or non-patterned portion 234. In other words, the controller 190 can differentiate between the patterned portion 232 and non-patterned portion 234 even if both are at least partially obscured by the same layer. Additionally, the data obtained by the orientation sensor 250 can show variations in the material being scanned, such as variations in the area of the non-patterned portion 234, even if a layer is fully or partially covering the front surface 230.

[0074] Figure 3A illustrates a top schematic plan view of the polishing station 124 to show the carrier head 210 in the scan position to find the reference mark 236. The conditioning assembly 132, the first fluid delivery arm 135, and the second fluid delivery arm 160 are omitted. The carrier head 210 is moveablerelative to the polishing pad 204 along a sweep path 302 to sweep the substrate 115 along the polishing surface 204A during the polishing process. The endpoint sensors 224 cross the sweep path 302 as the platen 202 rotates. The endpoint sensors 224 pass beneath the substrate 115 when the carrier head 210 places the substrate 115 at one or more positions along the sweep path 302 that is in the travel path of the endpoint sensors 224 as the platen 202 rotates. The windows 227 above the sensors 224 are shown in Figure 3A.

[0075] The carrier head 210 is shown in a scan position with the edge of the front surface 230 (Figure 3B) being at least partially positioned above the orientation sensor 250. The carrier head 210 is rotated relative to the orientation sensor 250 and the platen 202 while the orientation sensor 250 makes a scan of the substrate 115 edge to locate the reference mark 236. The carrier head 210 is moved to the scan position after the substrate 115 is transferred to a polishing station 124 from a different polishing station 124 in the polishing module 106 to allow a scan 310 (see Figure 3B) to be taken of the front surface 230 to ascertain the rotational orientation of the substrate 115.

[0076] Figure 3B illustrates the scan 310 of the front surface 230 of the substrate 115 by the orientation sensor 250. The scan 310 shows the path where the orientation sensor 250 passes below the front surface 230 to collect data as the carrier head 210 rotates the substrate 115 relative to the orientation sensor 250. The scan 310 is made near the edge of the front surface 230. The scan 310 is made close enough to the edge of the substrate 115 such that the scan 310 passes through part of the reference mark 236. In some embodiments, the orientation sensor 250 makes a scan 310 below only the non-patterned surface 234 when the carrier head 210 is in the scan position. Alternatively, the orientation sensor 250 may complete a scan 310 along that edge of the substrate 115 that passes across both the patterned surface 232 and the non-patterned surface 234.

[0077] The orientation sensor 250 collects data about the front surface 230 along the scan 310. This data is sent to the controller 190 (Figure 1 ) for analysis to determine the location of the reference mark 236. The first head encoder196 simultaneously records the rotational position of the carrier head 210 while the orientation sensor 250 collects data along the scan 310. The controller 190 correlates the data obtained from the orientation sensor 250 with the rotational position of the carrier head 210 for which the data was obtained. In other words, the controller 190 is able to match the data obtained from the orientation sensor 250 with the rotational position of the carrier head 210. This allows the controller 190 to analyze the data to determine the location of the reference mark 236 in relation to the rotational orientation of the carrier head 210. Once the location of the reference mark 236 relative to the carrier head 210 is known, then the rotational orientation of the substrate 115 is known. Additionally, the location of the hot spot 280 relative to the reference mark 236 is stored on the hot spot encoder 198. The controller 190 can correlate the location of the hot spot 280 relative to the reference mark 236 with the known rotational orientation of the substrate 115. In other words, the controller 190 can ascertain the location of the hot spot 280 relative to the carrier head 210 based on the rotational orientation of the substrate 115. Furthermore, the controller 190 can ascertain the location of the hot spot 280 on the polishing surface 204A based on the information of the platen encoder 195, first head encoder 196, second head encoder 197, and hot spot encoder 198.

[0078] In some embodiments, the carrier head 210 makes just one revolution about the carrier head axis 216 for the orientation sensor 250 to collect sufficient data along the scan 310 to determine the location of the reference mark 236. In other embodiments, the carrier head 210 makes more than one complete revolution to collect sufficient data along the scan 310 to determine the location of the reference mark 236.

[0079] In some embodiments, the platen 202 and the carrier head 210 both rotate as the orientation sensor 250 scans the substrate 115. In other embodiments, the platen 202 remains stationary while the carrier head 210 is rotated to allow the orientation sensor 250 to scan the substrate 115. The controller 190 may cause the platen 202 to begin rotating to start the CMP process once the rotational orientation of the substrate 115 is ascertained.

[0080] Figure 4 illustrates a graph 400 an exemplary signal 401 of the data collected by the orientation sensor 250 as it scanned the front side of the rotating substrate 115. This signal 401 shows the signal intensity at different rotational positions of the carrier head 210. This scanned substrate 115 has a different front surface than the front surface 230 shown in Figure 2B and Figure 3B. However, the scanned substrate 115 has a front surface with similar features as described to the front surface 230. Thus, the same reference signs will be used to explain the analysis of the signal 401. Additionally, the signal produced by the orientation sensor 250 will depend on the shape and / or material of the non-patterned portion 234 and patterned portion 232. Thus, signal 401 shown in Figure 4 is merely an example of one signal obtained during a scan of an exemplary substrate 115 to explain how the controller 190 is able to locate the reference mark 236.

[0081] The X-axis in Figure 4 shows the rotational position of the carrier head 210. The Y-axis of the graph 400 shows the signal intensity in arbitrary units (A.U.) at the rotational position of the carrier head 210. The signal intensity fluctuates across the rotational orientation of the carrier head 210. This is because the signal reflects the properties of the material scanned. In some embodiments, the orientation sensor 250 may register a more intense signal when scanning the material of the non-patterned portion 234 than material on the patterned portion 232. For example, the orientation sensor 250 may register a more intense signal for the barrier material on the non-patterned surface 234 than the material covering the patterned surface 232. A more intense signal may be registered even if the underlying barrier material on the non-patterned portion 234 is partially underneath a layer formed on both the patterned portion 232 and non-patterned portion 234. The signal intensity may correspond to the size of the area of the non-patterned portion 234 scanned by the orientation sensor 250. In other words, variations in the area of the nonpattered portion 234 lead to variations in the signal. For example, large spikes 402 in the signal 401 correspond to a portion of the non-patterned surface 234 with a larger surface area than the surface area of the non-patterned surface 234 corresponding to the smaller spikes 403. The differences in area variationin the non-pattered portion 234 may be detected even if the front surface 230 is fully or partially covered by a layer. However, the overall signal intensity may be lower or higher for a substrate 115 with a layer formed over the front surface 230 than the signal intensity obtained when scanning a substrate 115 that does not have a layer at least partially covering both the patterned portion 232 and the non-patterned portion 234. For example, the signal is higher if the layer covering both the patterned portion 232 and non-patterned portion 234 is composed of a conductive material, such as a metal.

[0082] The signal 401 will generally repeat in some embodiments, as shown in Figure 4, due to the symmetry of the non-patterned surface 234 about the first line of symmetry 235. Thus, a pattern is present in the signal 401 that the controller 190 can analyze to find the location of the reference mark 236 relative to the carrier head 210, and thus the rotational orientation of the substrate 115 within the carrier head 210. In some embodiments, the analysis of the signal 401 includes determining a candidate for the part of the signal corresponding to the portion of the substrate 115 including the reference mark 236. The candidate is then analyzed for a reference mark signature 407 that corresponds with the reference mark 236. Once the reference mark signature 407 is found, then the controller 190 is able to determine the rotational orientation of the substrate 115 with respect to the carrier head 210.

[0083] The signal 401 includes a first pair 405 and a second pair 406 of large spikes 402. Figure 4 shows each pair of spikes 405, 406 disposed in a dashed region for explanation purposes. In this example, the large spikes 402 in the signal 401 correspond to either the first region 237 or the second region 238 of the non-patterned surface 232. The first and second pairs 405, 406 of spikes have a similar signal intensity due to the similarity of the surface area of the first regions 237 and second regions 238. Additionally, 180 degrees of carrier head 210 rotation, shown as D1 , is present between the center of the two pairs 405, 406 of spikes. This is expected as it corresponds with the symmetry of the nonpatterned surface 234.

[0084] Each pair 405, 406 of spikes 402 is a candidate for the signal corresponding to a portion of the substrate 115 that includes the reference mark 236. In other words, each pair of spikes 405, 406 is potentially the portion of the substrate having the first regions 237 that the reference mark 236 is located between. The controller 190 knows that the reference mark 236 is at a rotational position of the carrier head 210 corresponding to one of the candidates. In this case, the reference mark 236 is in the trough between large spikes 402 in one of the first and second pairs 405, 406 of spikes 402. The controller 190 analyzes the signal of the candidates for a reference mark signature 407. In this example, the scanned substrate 115 had a notch for a reference mark 236. The signal 401 shows a slight drop between the first pair 405 of large spikes 402 as compared to the signal between a second pair 406 of large spikes 402. This drop is caused by the notch being a break (e.g., discontinuity) in the non-patterned surface 234 causing the orientation sensor 250 to register a lower signal intensity at a rotational position of the carrier head 210. This drop in the signal is the reference mark signature 407. The reference mark signature 407 may be detected by comparing the signal of the candidate to a threshold, such as a threshold signal intensity. Thus, the reference mark 236 may be identified if the signal intensity meets or exceeds a threshold value of the signal intensity.

[0085] The controller 190 is able to determine that the notch is between the first pair 405 of large spikes 402, with the center of the second pair 406 of large spikes 402 being the point on the opposite side of the substrate 115 opposite the notch. In some embodiments, the controller 190 may use the center of the reference mark signature 407 to determine the rotational position of the notch relative to the carrier head 210. Since the reference mark 236 is at a fixed location of the substrate 115, the controller is able to use the location of the reference mark 236 to determine the rotational orientation of the substrate 115. Additionally, the controller 190 is able to determine that illustrated point 410 in the signal corresponds to a point of the non-patterned surface that is 90 degrees from the reference mark 236 along the outer edge of the substrate 115.

[0086] In some embodiments, where the reference mark 236 is a flat surface (e.g., flat, flat edge) rather than a notch, the signal associated with the first region 237 will be different than the second region 238 on the opposing side of the substrate. This is because the flat surface causes the first regions 237 to have less surface area than the second regions 238, since the edge of the substrate on the opposite side of the flat surface is rounded. In certain embodiments, the controller 190 is able to differentiate the signal obtained from the first regions 237 from the signal obtained from the second regions 238 based on this difference in surface area.

[0087] Alternatively, a scan of a substrate 115 with a flat surface as a reference mark may result in a reference mark signature 407 that is a drop in the signal intensity. As the carrier head 210 rotates the substrate 115 relative to the orientation sensor 250, the orientation sensor 250 may pass along or outside of the edge of the flat surface. For example, the signal intensity may drop over a period of rotation of the carrier head 210 where the orientation sensor 250 passes from underneath the front surface 230 and is scanning empty space due to the flat reference mark 236. The signal intensity increases again once the orientation sensor 250 passes back under the front surface 230. Thus, the drop in signal intensity is due to the orientation sensor 250 detecting a lack of a material associated with the front surface 230 of the substrate 115. The center of the reference mark 236 may correspond with the center of the drop in the signal intensity. In some embodiments, the controller 190 may use the drop in the signal intensity between two portions of the signal identified as first region 237 candidates to determine the location of the center of the flat surface relative to the carrier head 210.

[0088] Thus, the controller 190 is able to analyze the signal 401 obtained from the orientation sensor 250 to determine portions of the signal that are candidates for the portion of the non-patterned surface 234 that includes the reference mark 236. The portion of the signal that is a candidate may be a pair of spikes in the signal that are offset from one another candidate by 180 degrees. In other words, the controller 190 can identify a pair of candidates onopposite sides of the substrate 115. Once the candidate pair is identified, the controller 190 may analyze each candidate for the reference mark signature 407, such as a decrease in the signal intensity between a pair of spikes that indicates the presence of the reference mark 236. The reference mark signature 407 may be determined by comparing the two candidates to determine which one has the lowest signal intensity between the apex of the spikes.

[0089] In some embodiments, the non-patterned surface 234 of the substrate 115 may have a shape that causes the signal to contain two or more pairs of candidates. In other words, other portions of the non-patterned surface 234 may have a surface area similar to first regions 237 and second regions 238. The controller 190 analyzes each pair of candidates to determine which one has a reference mark signature 407. The detection of the reference mark signature 407 allows the controller 190 to determine where the reference mark 236 is in relation to the carrier head 210.

[0090] In some embodiments, the controller 190 may stop the analysis once the reference mark signature 407 is found prior to analyzing all the candidates. For example, the controller 190 may identify multiple candidates. The controller 190 then analyzes each candidate until the reference mark signature 407 is found. The non-analyzed candidates may not be analyzed by the controller 190 once the reference mark signature 407 is found. In some embodiments, however, each candidate is analyzed regardless of the reference mark signature 407 being found. For example, each candidate may be analyzed to confirm that the reference mark signature 407 was not a false positive.

[0091] In some embodiments, controller 190 locates the reference mark signature 407 by comparing the signal intensity of two or more candidates to a threshold. In other embodiments, the controller 190 is able to determine the location of the reference mark 236 once the threshold is met or exceeded without the controller 190 making a comparison between multiple candidates. In other words, the controller 190 may be able to locate the reference mark 236after a partial revolution of the substrate 115, and thus the carrier head 210, that is sufficient to locate the reference mark 236.

[0092] In some embodiments, the controller 190 locates the reference mark signature 407 without identifying candidates. For example, the controller 190 may compare the signal 401 to a threshold. The reference mark signature 407 is identified when the signal 401 meets or exceeds the threshold. By way of example, the reference mark signature 407 may be a drop in signal intensity to a threshold value of signal intensity. In some embodiments, the controller 190 may compare the reference mark signature 407 to other features in the signal to confirm the location of the reference mark has been identified. For example, the controller 190 may compare the location of the reference mark signature with a signature associated with the first regions 237.

[0093] In some embodiments, the non-patterned portion 234 is not symmetrical about a line of symmetry. The controller 190 analyzes the signal to a threshold value, such as a threshold signal intensity, to determine the reference mark signature. For example, the controller 190 may analyze the signal for a drop that exceeds a signal intensity threshold. In some embodiments, the substrate 115 with the asymmetrical non-patterned portion may include region near the reference mark that produces a signal when scanned that the controller 190 can identify as a candidate for the portion of the substrate including the reference mark. This candidate is then analyzed for a reference mark signature 407.

[0094] The CMP System 100 (Figure 1 ) may process one or more types of substrates 115 to complete one or more polishing operation. The shape of the non-patterned surface 234 is substantially consistent across substrates of the same type. As a result, the orientation sensor 250 should produce a similar signal for each substrate of the same type, whether or not the non-patterned surface 234 is symmetrical about a line of symmetry. Thus, each type of substrate may have a reference signal stored in the controller 190 that includes a reference signature indicating the location of the reference mark 236. The type of substrate 115 may be input into the controller 190 to enable thecontroller 190 to determine the location of the reference mark 236 by comparing actual signal from the orientation sensor 250 to the reference signal.

[0095] Additionally, the material on the front surface 230 will be consistent since the CMP process will be repeating the same desired polishing operation for each type of substrate 115. For example, a scan may be made to find the reference mark 236 at a second polishing station 124 after polishing a first layer to a desired height at a first polishing station. Thus, the orientation sensor 250 should produce a similar signal for each substrate of the same type at the same stage of the polishing operation. The stage of the process may also be input into the controller 190, in addition to the substrate type, to enable the controller 190 to determine the location of the reference mark 236 by comparing actual signal from the orientation sensor 250 to the reference signal.

[0096] In some embodiments, the reference signal is the signal of the candidates and the reference mark signature is a portion of the signal of the candidate that meets or exceeds a threshold. In some embodiments, the actual signal is overlaid with the reference signal to determine the location of the reference mark. For example, the reference signal may be translated a number of degrees to roughly align the reference signal with the actual signal to determine the reference mark signature, such as by aligning the reference mark signature 407 with a reference signature of the reference signal.

[0097] During a CMP process, the controller 190 uses the information gathered from the platen encoder 195, first head encoder 196, and second head encoder 197 to determine and track the position of the carrier head 210 relative to the platen 202. In other words, the controller 190 knows where the carrier head 210 is above the rotating platen 202 at any given point in time, including knowing the rotational orientation of the carrier head 210 relative to the platen 202. Once the controller 190 ascertains the rotational orientation of the substrate 115 relative to the carrier head 210, then the controller 190 similarly knows the rotational orientation and position of the substrate 115 relative to the rotating platen 202 and endpoint sensors 224 at any given point in time of the polishing process. Additionally, the controller 190 knows thelocation of the hot spot 280 based on the rotational orientation of the substrate 115. Thus, the controller 190 also knows the position of the hot spot 280 relative to the rotating platen 202 and endpoint sensors 224 at any given point in time of the polishing process.

[0098] The controller 190 uses the positional information of the substrate 115 and platen 202 to determine which portions of the front surface 230 are scanned by each endpoint sensor 224 during the endpoint analysis. In other words, since the position and rotational orientation of the substrate 115 relative to the carrier head 210 and platen 202 is known, the controller 190 is able to correlate the data collected by the endpoint sensors 224 to a known location on the front surface 230. The sweep position of the carrier head 210 relative to the platen 202 and the rotation of both the carrier head 210 and platen 202 may be coordinated such that each endpoint sensor 224 traverses the same scan path multiple times during the CMP process to scan the same area (e.g., same region) of the front surface 230. For example, the endpoint sensors 224 may repeatedly traverse underneath the hot spot 280 to monitor the polishing hot spot treatment. Obtaining data from the same area over the substrate repeatedly improves the signal to noise ratio of the data obtained by the endpoint sensors 224 since a consistent signal will be obtained by the endpoint sensor 224 at each scan that reflects the progression of the polishing process over time. Improving the signal to noise ratio improves the endpoint analysis, allowing for a more accurate determination of when the endpoint is reached to produce a desired and uniform polish across the patterned surface 232.

[0099] In conventional CMP processes, the orientation of the substrate 115 is not known after the transfer to the second polishing station 124. As a result, the controller does not know what parts of the substrate are being scanned during the endpoint analysis because the collected data cannot be correlated with a known location on the surface of the substrate. Thus, the endpoint analysis in a conventional CMP process is based on random portions of the substrate 115 scanned by the endpoint sensors. The CMP process disclosed herein, where the endpoint sensor data is correlated to known locations on thesubstrate 115, improves the endpoint analysis because controller 190 and operator are able to evaluate the CMP process over time over a known area of the substrate. Additionally, correlating the data obtained from endpoint sensors 224 with known areas of the substrate allows for the treatment of the hot spot 280 to be monitored.

[0100] Figure 5 illustrates the top view of the substrate 115 shown in Figure 2B showing an exemplary first endpoint scan path 501 , an exemplary second endpoint scan path 502, and an exemplary third endpoint scan path 503 across the front surface 230. Each endpoint scan path 501 , 502, 503 corresponds the path of a respective endpoint sensor 224 of the polishing station 124 shown in Figure 3A (see windows 227) takes as it passes below the front surface 230. As shown, each endpoint scan path is in the shape of an arc due to the motion of the carrier head 210 and the platen 202 during polishing. The first scan path 501 and second scan path 502 are shown passing across the hot spot 280. Each endpoint sensor 224 scans the outer surface along the respective endpoint scan path 501 , 502, 503 multiple times during a CMP process to facilitate the endpoint analysis and / or to facilitate in hot spot monitoring. In some embodiments, the data obtained by the endpoint sensor 224 along its scan path is used during the endpoint analysis to determine when the endpoint of the polish is reached. In some embodiments, the data obtained by the endpoint sensor 224 along its scan path is used to monitor the polish of a hot spot 280. The orientation of scans paths relative to one another may vary depending on the location of the endpoint sensors 224 relative to one another.

[0101] Additionally, the controller 190 (Figure 1 ) may analyze the data obtained where the scan path of two or more endpoint sensors 224 cross to evaluate the polish, such as the endpoint of the CMP process or the progression of the hot spot treatment. For example, the controller 190 may analyze the data obtained at point 511 , where the first scan path 501 and third scan path 503 cross, to analyze the endpoint of the CMP process. This data may be used to plot a trace of the CMP process. Additionally, the controller 190 may analyze the data obtained at point 512, where the second scan path502 and third scan path 503 cross, and point 513, where the first scan path 501 and second scan path 502 cross, to evaluate the endpoint of the CMP process. The data obtained at each point 511 , 512, 513 may be used to plot a separate trace of the endpoint process during the endpoint analysis. In some embodiments, the controller 190 may also compare the data obtained where the scan path of two or more endpoint sensors 224 cross to confirm that the data obtained from each endpoint sensor 224 is consistent. The treatment of a hot spot 280 may be monitored similar to the end point, such as comparing a plot of separate traces along the hot spot 280 to other regions on the front surface 230 to evaluate when the hot spot 280 has been removed, such as when the trace of the hot spot 280 is similar to the trace of other regions of the front surface 230.

[0102] The controller 190 is able to use the position and orientation of the substrate 115 to correlate the data obtained by an endpoint sensor 224 with each location of the front surface 230 along the scan path of the endpoint sensor 224, such as being able to correlate the data to each die 233. Thus, the hot spot treatment during the CMP process may be evaluated based one or more particular dies 233 that includes a portion of the hot spot 280. Additionally, the endpoint analysis may be evaluated based on one or more particular dies 223.

[0103] In some embodiments, the position of the carrier head 210 and platen 202 may be coordinated such that an endpoint sensor 224 passes below a desired die 233 one or more times during the CMP process to evaluate the progression of the CMP process for that specific die 233. Similarly, the carrier head 210 and platen 202 may be coordinated such that an endpoint sensor 224 passes below a hot spot 280 one or more times during the CMP process to evaluate the progression of the hot spot treatment for that particular hot spot 280. In some embodiments, the carrier head 210 and platen 202 may be coordinated such that the endpoint sensor 224 oscillates between different scan paths along the front surface 230.

[0104] In some embodiments, the carrier head 210 may be moved to the scan position one or more times during a CMP process to allow the orientation sensor 250 to scan the edge of the substrate 115 to determine the rotational orientation of the substrate 115 relative to the carrier head 210. If the rotational orientation of the substrate 115 has changed, then the controller 190 is able to use the updated orientation during the endpoint analysis and during a hot spot treatment.

[0105] Figure 6 shows a trace 600 generated from the data obtained from an endpoint sensor 224 during a CMP process. This trace 600 may be used during the endpoint analysis to determine when the endpoint of the polish has been reached. A separate trace 600 may be made for each endpoint sensor 224 to enable the evaluation of the CMP process at different points on the surface of the substrate. For example, the progression of the trace 600 may be used to change the pressure applied to the substrate 115 by the diaphragm 212 to adjust the rate of polishing. Figure 6 shows the trace 600 over a portion of the substrate that does not include a hot spot 280.

[0106] The signal from the endpoint sensors 224 can be sampled to generate one or more measurements 610 for each scan of the endpoint sensor 224 across the substrate 115. Thus, over multiple scans, the endpoint monitoring system generates a sequence of measured values 610. This sequence of measured values 610 comprises the trace 600. In some implementations, measurements within a scan or from multiple scans can be averaged or filtered, e.g., a running average can be calculated, to generate the measurements 610 of the trace 600. For example, each measured value 610 may reflect a measurement made where the path of two or more endpoint sensors crossed to scan the same area of the front surface 230. The accuracy of the trace 600 is increased since the endpoint sensor 224 is scanning the same area of substrate to obtain the measured value 610.

[0107] The sequence of measured values 610 can be used to determine an endpoint or a change to the polishing parameters, e.g., to reduce within-wafer non-uniform ity. For example, a function 620 (of measured value versus time)can be fit to the measured values 610. The function 620 can be a polynomial function, e.g., a linear function. An endpoint can be predicted based on a calculated time at which the linear function 620 reaches a target value 630. In some embodiments, the endpoint is reached when the trace 600 passes a threshold. In some embodiments, the trace may reflect a measurement from the endpoint sensor at a particular die on the surface of the substrate. Thus, the endpoint of a particular die on the substrate can be evaluated during the CMP process.

[0108] The hot spot treatment may be monitored similarly to the endpoint analysis. For example, the trace of the hot spot 280 may be compared to a trace 600, which may be the trace of an area of the front surface 230 that does not include the hot spot 280. In some embodiments, the controller 190 repeatedly delivers the second fluid to the polishing surface 204A until the trace of the hot spot 280 is similar to the trace 600. In some embodiments, the controller 190 may instruct the delivery of a second fluid 262 that increases the rate of polish if the signal from the hot spot measurement is greater than the signal of the measured value 610 at the same point in time by a threshold amount. Similarly, the controller 190 may instruct the delivery of a second fluid 262 that reduces the polishing rate if the signal from the hot spot measurement is less than the measured value 610 at the same point in time by a threshold amount. The threshold amount may be a percentage, such as the signal of the hot spot measurement being greater or less than 10% of the signal obtained for a measured value 610 of the trace 600.

[0109] As mentioned above, the second fluid delivery arm 160 delivers the second fluid to a radial position on the polishing surface 204A that will pass underneath a targeted area of the substrate that includes the hot spot 280.

[0110] Figures 7A and 7B illustrates an exemplary top schematic plan view of the polishing station 124 shown in Figure 2A to show the delivery of the first fluid 222 and the second fluid 262 onto the polishing pad 204. Figure 7A shows a first amount of the second fluid 262 on the polishing surface 204A delivered a second radial position 720. Figure 7B shows the polishing station 124 afterthe passage of time such that the second fluid 262 on the polishing surface 204A is positioned to treat the hot spot 280 on the substrate 115. The conditioning assembly 132, the first fluid delivery arm 135, and the second fluid delivery arm 160 are omitted.

[0111] The first fluid delivery arm 135 delivers first fluid to the polishing surface 204A at a first radial position 710. This first radial position 710 may be a fixed position or the position of the first fluid delivery arm 135 may change to adjust the position of the first radial position 710. The first fluid spreads out over the polishing surface 204A after being delivered at the first radial position 710.

[0112] The second fluid delivery arm 160 delivers the second fluid 262 to the polishing surface 204A at a second radial position 720. The actuator 264 and / or the length of the arm are coordinated to position the fluid delivery head 261 above the second radial position 720. The second radial position 720 is selected to treat a targeted area on the front surface 230 of the substrate 115 that includes one or more hot spots, such as the hot spot 280. The pad 204 and carrier head 210 are rotating. The hot spot 280 is rotating along with the carrier head 210. The carrier head 210 is also sweeping along a sweep path (see e.g., sweep path 302 in Figure 3A) relative to the pad 204. The controller 190 (Figure 1 ) uses the platen encoder 195, first head encoder 196, second head encoder 197, and hot spot encoder 198 to determine the location on the polishing surface 204A to deliver the second fluid 262 such that the second fluid 262 will pass underneath the targeted area. The second radial position 720 may be selected based on where the hot spot 280 will pass over at a point in time based on the rational speed of the polishing pad 204, projected location of the carrier head 210, and projected radial position of the hot spot relative to the carrier head 210. The second radial position 720 is also selected to be outside the circumference of the carrier head 210 such that the fluid delivery head 261 can deliver the fluid onto the polishing surface 204A without contacting the carrier head 210 and without dispersing the second fluid 262 onto the back side of the carrier head 210.

[0113] The second fluid 262 disperses over a portion of the polishing surface 204A when delivered from the fluid delivery head 261. This portion covered by the second fluid 262 is shown as a treatment region 722 in Figure 7A. The second fluid 262 may mix with the first fluid 222 when delivered onto the polishing pad 204. The second fluid 262 adjusts a polishing characteristic, such as the polishing rate, of the treatment region 722 to treat the hot spot 280. The amount of second fluid 262 delivered to the second radial position 720 is selected to treat the targeted region of the front surface 230. In other words, the amount of second fluid 262 is selected to disperse over a localized area of the polishing surface 204A. The amount of second fluid 262 can be adjusted based on the size of the hot spot 280. The amount of second fluid 262 dispersed may also be selected to achieve the desired polishing characteristics while minimizing the area of the region 722 to decrease the amount of the front surface 230 that interacts with the second fluid 262. In other words, the amount of second fluid 262 may be selected to target the hot spot 280 while minimizing the impact to the polishing of the other portions of the front surface 230.

[0114] Figure 7B illustrates the polishing station 124 shown in Figure 7A after the passage of a time period. As shown, the pad 204, carrier head 210, and hot spot 280 have rotated to a new position. The carrier head 210 has also moved along the sweep path relative to the pad 204. The treatment region 722 covered by the second fluid 262 is now disposed underneath the targeted area of the front surface 230 of the substrate 115. This allows the second fluid 262 to interact with the hot spot 280. As shown, the region 722 may interact with a portion of the front surface 230 around the hot spot 280.

[0115] The second fluid delivery arm 160 may deliver the second fluid multiple times during a CMP process to treat the hot spot. The position of the second radial position 720 may change based on the location of the carrier head 210, pad 204, and hot spot 280, when additional second fluid needs to be delivered to treat the hot spot 280. The actuator 264 and / or the length of the arm are coordinated to position the fluid delivery head 261 above the updated position of the second radial position 720.

[0116] In some embodiments, the second fluid delivery arm 160 synchronizes the delivery of the second fluid 262 with the movement of the carrier head 210. The delivery may be synchronized by based on the rotational rate of the platen 202 and / or the carrier head 210.

[0117] Figures 8A-8C illustrate a schematic top view of a portion of the polishing station 124 to illustrate the synchronized delivery of the second fluid 262 onto the pad 204 by the second fluid delivery arm 160. As shown in Figure 8A, an amount of second fluid 262 is pulsed onto the polishing pad 204 at a first position 820 to interact with the hot spot 280. The first position 820 is selected such that the second fluid 262 pulsed onto the pad 204 will interact with the hot spot 280 once the pad 204 and carrier head 210 each rotate the hot spot 280 over the second fluid 262. The second fluid 262 is shown on the pad 204 as a first treatment region 822.

[0118] Figure 8B illustrates the hot spot 280 over the first treatment region 822. In other words, the platen 202, carrier head 210, and substrate 115 have each rotated from the position shown in Figure 8A. As shown, the second fluid delivery arm 160 is not delivering fluid to the pad 204. Instead, the controller 190 is waiting until the hot spot 280 is in a position such that the second fluid 262 can be delivered and intersect with the hot spot 280.

[0119] Figure 8C illustrates the hot spot 280 no longer being disposed over the first treatment region 822 due to the continued rotation of the platen 202. The hot spot 280 is now in a position that will allow the controller 190 time cause the delivery of the second fluid 262 onto the pad 204 to intersect with the hot spot 280. The second fluid delivery arm 160 delivers a second pulse of the second fluid 262 to the pad 240 at the radial position 820. This second fluid 266 delivered as the second pulse is shown on the pad 204 as a second treatment region 824. Continued rotation of the pad 204 and carrier head 210 will pass the second treatment region 824 underneath the hot spot 280 similarly to how the first treatment region 822 is shown in Figure 8B.

[0120] The time period between pulses of the second fluid 262 is selected based on the rotational speed of the carrier head 210, rotational speed of the platen 202, and the location of the hot spot 280. For example, the time between the first pulse of the second fluid 262, which is shown as treatment region 822, and the second pulse of the second fluid 262, shown as the second treatment region 824, may be about 1 second. In other words, the controller 190 may control the rotational speed of both the carrier head 210 and the platen 202 such that the second fluid 262 is delivered in one second on, one second off, pulses to treat the hot spot 280.

[0121] In some embodiments, the delivery location (e.g., radial position 820) of the subsequent pulse, such as the second pulse, may change based on the location of the carrier head 210 along the sweep path. In other words, the second arm 162 may move the fluid delivery head 261 to a new position relative to the polishing surface 204A to subsequent pulses of the second fluid 262. In some embodiments, a different second fluid delivery arm 160 may be used to deliver one or more of the pulses.

[0122] In some embodiments, the controller 190 may set a speed of rotation of the platen 202 and the speed of rotation of the carrier head 210 to pass each pulse of the second fluid underneath the hot spot 280. For example, the rotational speed of the platen 202 and the speed of rotation of the carrier head 210 may be set to synchronize the delivery of the second fluid with the rotation of the carrier head 210 to deliver a plurality of pulses of second fluid 262 at a radial position that passes underneath the hot spot 280.

[0123] Figure 9 illustrates a flow chart of an exemplary method 900 of processing a substrate (e.g., the substrate 115). The controller 190 may control each operation of the method 900.

[0124] At operation 902, the substrate 115 is polished on a first pad 204 coupled to a first platen 202 of a first polishing station 124. One or more endpoint sensors 224 may monitor the endpoint of the polish of the front surface 230 of the substrate 115.

[0125] At operation 904, the substrate 115 is transferred to a pad 204 of a second polishing station 124 by a carrier head 210. Operation 904 occurs after the first polishing station 124 completes the polish of the substrate 115.

[0126] At operation 906, the carrier head 210 moves to a scan position to place the edge of the substrate 115 above an orientation sensor 250 disposed at the rotation center of the platen 202 coupled to the pad 204.

[0127] At operation 908, the orientation sensor 250 scans the edge of the substrate 115 to produce a signal. The carrier head 210 rotates the substrate 115 relative to the platen 202 and the orientation sensor 250 during the scan of the edge.

[0128] At operation 910, the signal is analyzed to locate the reference mark 236 of the substrate 115 to determine the rotational orientation of the substrate 115 relative to the carrier head 210.

[0129] In some embodiments, operation 910 includes determining one or more candidates in the signal for a portion of the substrate 115 including the reference mark 236. The one or more candidates are then analyzed for a reference mark signature. In some embodiments, the reference mark signature is a drop in the intensity of the signal. In some embodiments, the reference mark signature is identified when the drop in the signal intensity reaches or exceeds a threshold.

[0130] In some embodiments, operation 910 includes identifying at least one pair of candidates for a portion of the substrate including the reference mark that are located 180 degrees apart. Each candidate is then analyzed for a reference mark signature.

[0131] In some embodiments, operation 910 includes analyzing the signal to identify a reference mark signature. In some embodiments, the reference mark signature is identify by comparing the signal to a threshold. In some embodiments, the reference mark signature is identified after a partial revolution of the carrier head 210 relative to the orientation sensor 250. In someembodiments, the reference mark signature is identified by comparing the signal to a reference signal for a substrate of the same type.

[0132] At operation 912, the controller 190 correlates the location of the hot spot 280 relative to the reference mark 236 to the rotational orientation of the substrate 115. This allows the controller 190 to determine the location of the hot spot 280 during the polishing process, such as determining the location of the hot spot 280 relative to the rotational orientation of the carrier head 210 and the rotational orientation of the pad 204.

[0133] In some embodiments of operation 912, the location of the hot spot 280 is obtained by the one or more endpoint sensors 224 during the polishing process. For example, the CMP polishing process may begin before beginning operation 912 to obtain the location of the hot spot 280 relative to the reference mark 236. In some embodiments, the location of the hot spot 280 is obtained by the metrology station 117.

[0134] In some embodiments of operation 912, the controller 190 may assume the location of the hot spot 280 relative to the reference mark 236, such as when the substrate 115 being processed is part of a batch of similar substrates. For example, the controller 190 may assume the location of the hot spot 280 when multiple substrates 115 from the same batch have been observed, whether by analysis in the metrology station 117 or by analysis of the endpoint sensors 224, to consistently develop a hot spot at one or more locations on the front surface 230 relative to the reference sign 236.

[0135] At operation 914, the front surface 230 of the substrate 115 is polished within the second polishing station by rotating the pad 204 and the carrier head 210 simultaneously. The diaphragm 212 within the carrier head 210 urges the substrate against the pad 204. One or more endpoint sensors 224 monitor the endpoint of the polishing operation performed in the second polishing station. These endpoint sensors 224 obtain data used to determine the endpoint of the polishing process.

[0136] In some embodiments of operation 914, the rotational orientation of the substrate 115 relative to the carrier head 210 is used to determine which portions of the front surface 230 is being scanned along a scan path of each endpoint sensor 224. The movement and rotation of the carrier head 210 and the rotation of the platen 202 may be coordinated such that each endpoint sensor 224 moves along the same scan path a plurality of times during the polishing process to obtain data of the front surface along the scan path.

[0137] In some embodiments of operation 914, a first die of a plurality of dies 233 formed on the pattern surface 232 is selected for endpoint analysis. The rotation and position of the carrier head 210 and the rotation of the platen 202 are coordinated to scan the first die. The first die may be scanned once or it may be scanned a plurality of times during the polishing process.

[0138] In some embodiments of operation 914, the carrier head 210 may optionally be moved to the scan position one or more times to allow the orientation sensor 250 scan the edge of the substrate 115 to determine the rotational orientation of the substrate 115 relative to the carrier head 210. If the rotational orientation of the substrate 115 has changed, then the controller 190 is able to use the updated orientation to perform the endpoint analysis.

[0139] At operation 916, the substrate 115 is treated to remove or substantially remove the hot spot 280 while the front surface 230 is polished on the pad 204 of the second polishing station 124. Operation 916 occurs simultaneously with operation 914. The controller 190 causes the second fluid delivery arm 160 to deliver a first amount of second fluid 262 onto the polishing surface 204A at a first radial position. The first radial position is selected such that the first amount of second fluid 262, once delivered to the polishing surface 204A, will intersect with the hot spot 280 as the pad 204 and carrier head 210 continue to move during the polishing process. For example, the controller 190 may use the platen encoder 195, first head encoder 196, second head encoder 197, and hot spot encoder 198 to determine the position of the first radial position. The controller 190 may instruct the actuator 264 to rotate the second arm 162 to place the fluid delivery head above the first radial position.

[0140] Operation 916 may also include delivering additional amounts of the second fluid 262 to treat the hot spot. For example, controller 190 may cause the second fluid delivery arm 160 to deliver a second amount of the second fluid 262 onto the polishing surface 204A at a second radial position.

[0141] The second radial position is selected such that the second amount of second fluid 262, once delivered to the polishing surface 204A, will intersect with the hot spot 280 as the pad 204 and carrier head 210 continue to move during the polishing process. For example, the controller 190 may use the platen encoder 195, first head encoder 196, second head encoder 197, and hot spot encoder 198 to determine the position of the second radial position. The second radial position may be the first radial position or the second radial position may be a different than the first radial position. The controller 190 may instruct the actuator 264 to rotate the second arm 162 to place the fluid delivery head above the second radial position.

[0142] Operation 916 may include the delivery of more than the first amount and the second amount of the second fluids 262, such as the delivery of a third amount and a fourth amount of the second fluid 262. Each amount of the second fluid 262 may be delivered as a pulse from the fluid delivery head 261 . Each pulse may be delivered periodically to the polishing surface 204A at the same or different radial position as other pulses. Each pulse may be synchronized with the rotation of the carrier head 210, such as delivering each pulse when the hot spot 280 is at a rotational position of the carrier head 210 such that the hot spot 280 will pass over the second fluid 262 pulsed onto the polishing surface 204A. The pulses may also be synchronized, in addition to the location of the hot spot 280 relative to the carrier head 210, based on the rotational speed of the carrier head 210 and the rotational speed of the pad 204.

[0143] In some embodiments of operation 916, each pulse of an amount of second fluid 262 may be separated by around one second. For example, the controller 190 may cause the second fluid delivery arm 160 to pulse the first amount of the second fluid 262 onto the pad 204 for about one second. Thecontroller 190 then stops delivery of the second fluid 262 for about one second. Then the controller 190 causes the second fluid delivery arm 260 to pulse the second amount onto the pad 204 for about 1 second. This cycle of pulses may repeat until the hot spot 280 is removed.

[0144] The first amount and second amount of second fluid may have a composition to increase or decrease the polishing rate. In some embodiments, the first amount and second amount of second fluid may be deionized water to dilute or clear the first fluid from a portion of the polishing pad 204 to decrease the polishing rate. Each amount of the pulsed second fluid 262 may have the same or different composition. In some embodiments, multiple pulses of the second fluid 262 with the same composition may be delivered to the pad 204 that are followed by pulses with a different composition.

[0145] In some embodiments, operation 916 may include the controller 190 setting a rotational speed of the carrier head 210 and the platen 202, such as setting a ratio between the speed of rotation of the carrier head 210 and platen 202, to intersect the second fluid 262 deposited onto the polishing surface 204A with the hot spot 280.

[0146] Operation 916 may continue until the hot spot 280 is removed. The progression of the polish of the hot spot 280 may be monitored by the endpoint sensors 224. For example, the endpoint sensors 224 may measure the change in the thickness of the hot spot 280 over time to determine a polishing rate of the targeted area of the front surface 230 that includes the hot spot 280. The composition of the second fluid 262 may be changed to adjust the polishing rate of the targeted area. For example, the controller 190 may determine that the hot spot 280 is not being removed at a sufficient rate relative to the progression of the polish of the other areas of the front surface 230. The composition of the second fluid 262 may be changed to increase the polishing rate of the targeted area. Similarly, the composition of the second fluid 262 may be changed to decrease the polishing rate if the hot spot 280 is being removed faster than desired.

[0147] Figure 10 illustrates a flow chart of an exemplary method 1000 of processing a substrate 115. The controller 190 may control each operation of the method 1000.

[0148] At operation 1002, the front surface 230 of the substrate 115 disposed in the carrier head 210 of a polishing station 124 is placed on the polishing surface 204A. The substrate 115 may be placed on the polishing surface 204A after being polished on a different polishing station 124.

[0149] At operation 1004, the first fluid 222 is delivered onto the polishing surface 204A using the first fluid delivery arm 135. The first fluid 222 may be delivered in a continuous stream while the front surface 230 of the substrate 115 is polished.

[0150] At operation 1006, a location of the hot spot 280 on the front surface 230 relative to the reference mark 236 is determined. In some embodiments, the location of the hot spot 280 may be determined using the pre-aligner 118 and the metrology station 117. In some embodiments, operation 1006 occurs before operation 1002, such as the substrate 115 being transferred to the polishing surface 204A after the substrate 115 is aligned in the pre-aligner 118 and analyzed in the metrology station 117. In some embodiments, the location of the hot spot 280 is determined using endpoint sensors 224 in the pad of the polishing station 124.

[0151] In some embodiments of operation 1006, the controller 190 may assume the location of the hot spot 280 relative to the reference mark 236, such as when the substrate 115 being processed is part of a batch of similar substrates. For example, the controller 190 may assume the location of the hot spot 280 when multiple substrates 115 from the same batch have been observed, whether by analysis in the metrology station 117 or by analysis of the endpoint sensors 224, to consistently develop a hot spot at one or more locations on the front surface 230 relative to the reference mark 236.

[0152] At operation 1008, the rotational orientation of the substrate 115 relative to the carrier head 210 is determined. Once the rotational orientation of the substrate 115 relative to the carrier head 210 is known, then the location of the hot spot 280 relative to the carrier head 210 is known. In some embodiments, the rotational orientation of the substrate 115 relative to the carrier head 210 may be obtained using the pre-aligner 118. In some embodiments, the rotational orientation of the substrate 115 is determined using the orientation sensor.

[0153] For example, the carrier head 210 may be moved to a scan position to allow the orientation sensor 250 to scan the edge of the substrate 115. The data obtained by the orientation sensor 250 is used to determine a location of a reference mark of the substrate in relation to a carrier head 210 engaged with (e.g., holding) the substrate 115. In some embodiments, operation 1008 includes identifying one or more candidates for a portion of the substrate 115 including the reference mark 236 and then analyzing each candidate for a reference mark signature. In some embodiments, operation 1008 includes comparing the data to a threshold. The location of the reference mark 236 is determined when the data meets or exceeds the threshold.

[0154] At operation 1010, the hot spot 280 is treated while the front surface 230 is polished on the polishing surface 204A. The pad 204 and carrier head 210 are rotated during polishing. The carrier head 210 may sweep along a sweep path during polishing. In some embodiments, the hot spot 280 is treated by determining a first radial position on the polishing surface 204A to pulse a first amount of second fluid 262. The first radial position is selected such that the first amount of second fluid 262, once delivered to the polishing surface 204A, will intersect with the hot spot 280 as the pad 204 and carrier head 210 continue to move during the polishing process. For example, the controller 190 may use the platen encoder 195, first head encoder 196, second head encoder 197, and hot spot encoder 198 to determine the position of the first radial position. The controller 190 may instruct the actuator 264 to rotate the second arm 162 to place the fluid delivery head above the first radial position. The firstamount of the second fluid 262 is then pulsed onto the polishing pad 204 at the first radial position.

[0155] Operation 1010 may also include delivering additional amounts of the second fluid 262 to treat the hot spot 280. For example, controller 190 may cause the second fluid delivery arm 160 to pulse a second amount of the second fluid 262 onto the polishing surface 204A at a second radial position.

[0156] The second radial position is selected such that the second amount of second fluid 262, once delivered to the polishing surface 204A, will intersect with the hot spot 280 as the pad 204 and carrier head 210 continue to move during the polishing process. For example, the controller 190 may use the platen encoder 195, first head encoder 196, second head encoder 197, and hot spot encoder 198 to determine the position of the second radial position. The second radial position may be the first radial position or the second radial position may be a different than the first radial position. The controller 190 may instruct the actuator 264 to rotate the second arm 162 to place the fluid delivery head above the second radial position.

[0157] Operation 1010 may include pulsing additional amounts of the second fluid 262 onto the polishing pad 204. Each pulse may be synchronized with the rotation of the carrier head 210, such as delivering each pulse when the hot spot 280 is at a rotational position of the carrier head 210 such that the hot spot 280 will pass over the second fluid 262 pulsed onto the polishing surface 204A. The pulses may also be synchronized, in addition to the location of the hot spot 280 relative to the carrier head 210, based on the rotational speed of the carrier head 210 and the rotational speed of the pad 204. In some embodiments of operation 1010, each pulse of an amount of second fluid 262 may be separated by around one second. For example, the controller 190 may cause the second fluid delivery arm 160 to pulse the first amount of second fluid 262 onto the pad 204 for about one second. The controller 190 then stops delivery of the second fluid 262 for about one second. Then the controller 190 causes the second fluid delivery arm 260 to pulse the second amount of secondfluid 262 onto the pad 204 for about 1 second. This cycle of pulses may repeat until the hot spot 280 is removed.

[0158] The first amount and second amount of second fluid 262 may have a composition to increase or decrease the polishing rate. In some embodiments, the first amount and second amount of second fluid 262 may be deionized water to dilute or clear the first fluid from a portion of the polishing pad 204 to decrease the polishing rate. Each amount of the pulsed second fluid 262 may have the same or different composition. In some embodiments, multiple pulses of the second fluid 262 with the same composition may be delivered to the pad 204 that are followed by pulses with a different composition.

[0159] In some embodiments, operation 1010 may include the controller 190 setting a rotational speed of the carrier head 210 and the platen 202, such as setting a ratio between the speed of rotation of the carrier head 210 and platen 202, to intersect the second fluid 262 deposited onto the polishing surface 204A with the hot spot 280.

[0160] Operation 1010 may continue until the hot spot 280 is removed. The progression of the polish of the hot spot 280 may be monitored by the endpoint sensors 224. For example, the endpoint sensors 224 may measure the change in the thickness of the hot spot 280 over time to determine a polishing rate of the targeted area of the front surface 230 that includes the hot spot 280. The composition of the second fluid 262 may be changed to adjust the polishing rate of the targeted area. For example, the controller 190 may determine that the hot spot 280 is not being removed at a sufficient rate relative to the progression of the polish of the other areas of the front surface 230. The composition of the second fluid 262 may be changed to increase the polishing rate of the targeted area. Similarly, the composition of the second fluid 262 may be changed to decrease the polishing rate if the hot spot 280 is being removed faster than desired.

[0161] 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.

Claims

What is claimed is:1 . A method of processing a substrate, comprising: placing a front surface of a substrate disposed in a carrier head on a polishing surface of a pad coupled to a platen; delivering a first fluid onto the polishing surface using a first fluid delivery arm; determining a location of a hot spot on the front surface; determining a rotational orientation of the substrate relative to the carrier head; and treating the hot spot while polishing the front surface on the polishing surface using a second fluid delivery arm to deliver a second fluid to the polishing surface, the treating comprising: determining a first radial position on the polishing surface to pulse a first amount of a second fluid such that the first amount of second fluid will at least partially pass underneath the hot spot; and pulsing the first amount of the second fluid onto the polishing surface at the first radial position using the second fluid delivery arm.

2. The method of claim 1 , the treating further comprising: determining a second radial position on the polishing surface to pulse a second amount of the second fluid such that the second amount of second fluid will at least partially pass underneath the hot spot; and pulsing the second amount of the second fluid onto the polishing surface at the second radial position.

3. The method of claim 2, wherein the second fluid delivery arm is moved to a first position to pulse the first amount of second fluid and moved to a second position to pulse the second amount of second fluid at the second radial position.

4. The method of claim 2, wherein the second amount of the second fluid has a different composition than the first amount of the second fluid.

5. The method of claim 1 , wherein the first radial position is determined based on at least the rotational speed of the carrier head, the rotational speed of the pad, the location of the hot spot, and the rotational orientation of the substrate relative to the carrier head.

6. The method of claim 1 , wherein the location of the hot spot is determined by a metrology station.

7. A method of processing a substrate, comprising: polishing a front surface of a substrate on a first pad coupled to a first platen; transferring the substrate from the first pad to a second pad coupled to a second platen with a carrier head; delivering a first fluid onto a polishing surface of the second pad; determining a location of a hot spot on the front surface; determining a rotational orientation of the substrate relative to the carrier head; and treating the hot spot while polishing the front surface on the second pad, the treating comprising: determining a first radial position on the polishing surface to pulse a first amount of a second fluid such that the first amount of second fluid will at least partially pass underneath the hot spot; and pulsing the first amount of the second fluid onto the polishing surface at the first radial position.

8. The method of claim 7, wherein the first radial position is determined based on at least the rotational speed of the carrier head, the rotational speed of the second pad, the location of the spot, and the rotational orientation of the substrate relative to the carrier head.

9. The method of claim 7, wherein the location of the hot spot is determined by one or more endpoint sensors disposed in the second pad.

10. The method of claim 7, wherein the treating further includes:obtaining a thickness of the hot spot with one or more endpoint sensors disposed in the second pad.11 . The method of claim 10, further comprising: pulsing a second amount of the second fluid at a second radial position based on the thickness of the hot spot.

12. The method of claim 7, the treating further comprising: determining a second radial position on the polishing surface to pulse a second amount of the second fluid such that the second amount of second fluid will at least partially pass underneath the hot spot; and pulsing the second amount of the second fluid onto the polishing surface at the second radial position.

13. The method of claim 12, wherein the second radial position is different than the first radial position.

14. The method of claim 12, wherein second fluid is pulsed onto the polishing surface by a fluid delivery head, wherein the fluid delivery head is moved from a first position above the first radial position to a second position above the second radial position prior to pulsing the second amount.

15. The method of claim 12, wherein pulsing the second amount of second fluid occurs one second after pulsing the first amount of second fluid.

16. The method of claim 12, wherein the second amount of the second fluid has a different composition than the first amount of the second fluid.

17. The method of claim 16, wherein the first amount of the second fluid increases the polishing rate of the hot spot and the second amount of the second fluid decreases the polishing rate of the hot spot.

18. A polishing system, comprising:a polishing station, including: a platen including a polishing pad; a carrier head configured to rotate a substrate including a reference mark and a front surface; a first fluid delivery arm configured to deliver a first fluid onto the polishing pad; a second fluid delivery arm configured to selectively deliver one or more pulses of a second fluid onto the polishing pad to treat a hot spot on the front surface, wherein the hot spot is located at a known position relative to the reference mark; an orientation sensor embedded in the platen at the rotational center of the platen, wherein the orientation sensor is configured to scan an edge of a substrate that includes a reference mark; and a controller in communication with the orientation sensor, the pad, the carrier head, and the second fluid delivery arm, wherein the controller is configured to analyze data obtained by the orientation sensor to identify a location of the reference mark relative to the carrier head, and wherein the controller is configured to control a position of the second fluid delivery arm relative to the pad to deliver one or more pulses at one or more radial positions on the pad to treat the hot spot.

19. The polishing system of claim 18, further comprising: at least one of a metrology tool or a pre-alignment station configured to determine the location of the hot spot relative to the reference mark before polishing the substrate.

20. The polishing system of claim 18, further comprising: a plurality of endpoint sensors embedded in the platen around the orientation sensor, each endpoint sensor configured to monitor a polishing rate of the hot spot, and wherein the controller is configured to cause a change in a composition of the second fluid based on the polishing rate of the hot spot.

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