Determining orientation of substrate in situ

Abstract

A method of processing a substrate includes polishing a front surface of the substrate on a first pad coupled to a first platen. The method further includes transferring, with the carrier head, the substrate from the first pad to a second pad coupled to a second platen. The method further includes moving the carrier head to a scanning position to place an edge of the substrate over an orientation sensor disposed at a center of rotation of the second pad. The method further includes scanning an edge of the substrate with a directional sensor to generate a signal. The method further includes analyzing the signal to locate a reference mark of the substrate to determine a rotational orientation of the substrate relative to the carrier head.

Description

[0001] background field

[0002] This disclosure relates to chemical mechanical polishing (CMP), and more specifically to analyzing the endpoints of CMP processes. Background Technology

[0003] Integrated circuits are typically formed on a substrate by sequentially depositing conductive layers, semiconducting layers, and / or insulating layers on a semiconductor substrate. Various manufacturing processes require planarizing the layers on the substrate. For example, one manufacturing step involves depositing a filler layer over a non-planar surface and then planarizing the filler layer. For some applications, the filler layer is planarized until the top surface of the patterned layer is exposed. For example, a metal layer may be deposited over a patterned insulating layer to fill trenches and holes in the insulating layer. After planarization, the remaining portions of the metal in the trenches and holes of the patterned layer form vias, plugs, and wiring to provide conductive paths between integrated circuits (ICs) on the substrate. As another example, a dielectric layer may be deposited over a patterned conductive layer and subsequently planarized to enable subsequent photolithography steps.

[0004] Chemical mechanical polishing (CMP) is a widely accepted planarization method. This planarization method typically requires mounting a substrate on a carrier head. The exposed surface of the substrate (the surface with deposited layers) is usually placed against a rotating polishing pad. The carrier head provides a controlled load on the substrate to push it against the polishing pad. A polishing slurry containing abrasive particles is typically supplied to the surface of the polishing pad and dispersed between the substrate and the polishing pad. The polishing pad and the carrier head each rotate at a constant speed, and the abrasive slurry removes material from one or more layers.

[0005] However, conventional CMP operations cannot determine the rotational orientation of the substrate relative to the carrier head after it has been transferred to the polishing pad. As a result, the rotational orientation of the substrate is unknown during the endpoint analysis of a conventional CMP process. There is a need in the art to determine the rotational orientation of the substrate relative to the carrier head in situ to improve the endpoint analysis of CMP processes. Summary of the Invention

[0006] In one embodiment, a method of processing a substrate includes polishing the front surface of the substrate on a first pad coupled to a first pressure plate. The method further includes using a carrier head to transfer the substrate from the first pad to a second pad coupled to a second pressure plate. The method further includes moving the carrier head to a scanning position to place an edge of the substrate over an orientation sensor disposed at the rotation center of the second pad. The method further includes using the orientation sensor to scan the edge of the substrate to generate a signal. The method further includes analyzing the signal to locate reference marks on the substrate to determine the rotational orientation of the substrate relative to the carrier head.

[0007] In one embodiment, a method of polishing a substrate includes scanning the edge of the substrate using an orientation sensor positioned at the center of rotation of a clamping plate. The method further includes analyzing data obtained by the orientation sensor to determine the position of a reference mark on the substrate relative to a carrier head holding the substrate. The method further includes polishing the front surface of the substrate. The method further includes monitoring the front surface during polishing using an endpoint sensor embedded in the clamping plate that scans the front surface. Monitoring includes using the determined position of the reference mark relative to the carrier head to identify the portion of the front surface being scanned by the endpoint sensor.

[0008] In one embodiment, a polishing system includes a polishing station comprising a pressure plate, a bearing head, orientation sensors, a plurality of endpoint sensors, and a controller. The pressure plate includes a polishing pad. The bearing head is configured to rotate a substrate. The orientation sensors are embedded in the pressure plate at the center of rotation of the pressure plate. The orientation sensors are configured to scan an edge of the substrate, including a reference mark. The plurality of endpoint sensors are embedded in the pressure plate surrounding the orientation sensors. Each endpoint sensor is configured to monitor the surface of the substrate being polished on the pad. The controller communicates with the orientation sensors and the endpoint sensors. The controller is configured to analyze data obtained by the orientation sensors to identify the position of the reference mark relative to the bearing head. Attached Figure Description

[0009] To gain a more detailed understanding of the features described above in this disclosure, reference can be made to the embodiments for a more specific description of the disclosure briefly outlined above, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only exemplary embodiments of this disclosure and are not intended to limit the scope of the disclosure, as other equivalent embodiments are permissible.

[0010] Figure 1 A schematic top view of an exemplary chemical mechanical polishing (CMP) system is depicted.

[0011] Figure 2A The embodiments described herein are depicted from Figure 1 A schematic cross-sectional view of an exemplary polishing station of a CMP system.

[0012] Figure 2B According to the embodiments described herein Figure 2A A top view of the front surface of a substrate being polished at a polishing station.

[0013] Figure 3A The embodiments described herein are depicted in the context of... Figure 2A A schematic top view of the bearing head positioned at the scanning location on the polishing pad of the polishing station.

[0014] Figure 3B The passage describes the implementation of the embodiments described herein. Figure 2A A top view of the front surface of the substrate scanned by the orientation sensor of the polishing station.

[0015] Figure 4 The passage describes the implementation of the embodiments described herein. Figure 2A An example signal obtained by the orientation sensor of the polishing station.

[0016] Figure 5 Illustrations depicting embodiments according to the description herein Figure 2A A top view of the front surface of the substrate, showing the scanning path of the sensor at the end of the polishing station.

[0017] Figure 6 A graph of an example trace obtained by an endpoint sensor during the CMP process is shown.

[0018] Figure 7A The embodiments described herein are shown in Figure 1 A partial cross-sectional view of the substrate being polished in the first polishing station of the CMP system.

[0019] Figure 7B The embodiments described herein are shown in Figure 1 A partial cross-sectional view of the substrate after polishing in the first polishing station of the CMP system.

[0020] Figure 7C The embodiments described herein are shown in the present invention. Figure 1 A partial cross-sectional view of a substrate being polished at the second polishing station of a CMP system.

[0021] Figure 7D The embodiments described herein are shown in Figure 1 A partial cross-sectional view of the substrate after polishing at the second polishing station of the CMP system.

[0022] Figure 8 This is a flowchart of a method for processing a substrate according to an embodiment described herein.

[0023] Figure 9 This is a flowchart of a method for processing a substrate according to an embodiment described herein.

[0024] To facilitate understanding, the same reference numerals have been used to identify common elements in the figures where possible. It is contemplated that elements and features of one embodiment may be advantageously incorporated into other embodiments without further description. Detailed Implementation

[0025] This article discloses an apparatus and method for in-situ determination of the rotational orientation of a substrate. This rotational orientation is used to improve endpoint analysis in chemical mechanical polishing (CMP) processes.

[0026] Figure 1 This 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 on which one or more layers are deposited) is processed in the CMP system 100 to polish the surface of the substrate 115.

[0027] A wet robot 108 is provided to transfer substrate 115 between the factory interface module 102 and the polishing module 106. The wet robot 108 can also be configured to transfer substrate 115 between the polishing module 106 and the cleaner 104. The factory interface module 102 includes a dry robot 110 configured to transfer substrate 115 between one or more cassettes 114, one or more transfer platforms 116, one or more metering stations 117, and one or more pre-aligner stations 118 of the factory interface 102. Substrate 115 is loaded into the CMP system 100 via cassette 114. Figure 1 In one embodiment depicted, four substrate storage boxes 114 are illustrated. A dry robot 110 within the factory interface 102 has sufficient range of motion to facilitate transfer between the four boxes 114 and one or more transfer platforms 116. Optionally, the dry robot 110 may be mounted on a rail or track 112 to laterally position the robot 110 within the factory interface module 102. The dry robot 110 is additionally configured to receive substrates 115 from a cleaner 104 and return the cleaned and polished substrates to the substrate storage boxes 114.

[0028] Figure 1 An exemplary polishing module 106 is illustrated, comprising a plurality of polishing stations 124 on which a substrate 115 is polished while being held in a carrier head 210 (e.g., a polishing head). Each polishing station 124 includes an adjustment assembly 132 and a polishing fluid delivery module 135. Although the polishing module 106 is illustrated as having three polishing stations 124, it may have more than three. For example, the polishing module 106 may have two pairs of polishing stations 124, each pair processing the substrate 115 independently of the other pair. The polishing stations 124 are sized to mate with one or more carrier heads 210 to facilitate the polishing of the substrate 115. The carrier heads 210 are coupled to a bracket (not shown) that is mounted to... Figure 1 The elevated track 128 is shown in dashed lines. The elevated track 128 allows for selective positioning of the bracket around the polishing module 106, which facilitates selective positioning of the carrier head 210 above the polishing station 124 and the loading cup 122. Figure 1In the embodiment depicted, the overhead track 128 has a circular configuration, which allows the carrier of the bearing head 210 to selectively and independently rotate and / or leave the loading cup 122 and polishing station 124. Furthermore, the overhead track 128 facilitates the sweeping rotation of the bearing head 210 relative to the polishing station 124 during polishing. The polishing station 124 will be described in more detail with reference to FIG. 2.

[0029] Each polishing station 124 includes a polishing pad 204 having a polishing surface capable of polishing a substrate 115 (e.g., polishing surface 204A in FIG. 2). Each polishing station 124 includes an adjustment assembly 132 and a polishing fluid delivery module 135. In one embodiment, the adjustment assembly 132 may include a pad adjustment assembly 140 that trims the polishing surface of the polishing pad 204 by removing polishing debris and opening holes in the polishing pad 204 using a pad adjustment disc 133. In another embodiment, the polishing fluid delivery module 135 may include a fluid delivery arm 134 for delivering slurry. In one embodiment, each polishing station 124 includes a pad adjustment assembly 132. In one embodiment, the fluid delivery arm 134 is configured to deliver a fluid flow (e.g., slurry 222 in FIG. 2) to the polishing station 124. The polishing pad 204 is supported on a pressure plate (e.g., pressure plate 202 in FIG. 2) that rotates the polishing pad 204 during processing. Each polishing station 124 includes a polishing pad 204 fixed to a rotatable pressure plate 202. Different polishing pads 204 can be used at different polishing stations 124 to control the removal of material from the substrate 115.

[0030] At least one loading cup 122 (such as Figure 1 The two loading cups 122 shown are located near the lower right corner of the polishing module 106, between the polishing stations 124 closest to the wet robot 108. The loading cups 122 can be used for 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 head (e.g., the carrier head 210 in FIG. 2).

[0031] Substrate 115 will typically have reference markings, such as notches, flat edges, or other types of features that can be used to identify the crystal orientation of substrate 115 and mark the rotational orientation of the front surface of substrate 115 relative to a central axis. In some embodiments, the factory interface module 102 may also include a pre-aligner 118 for positioning substrate 115 in a known and desired rotational orientation. Pre-alignment of substrate 115 with the desired rotational orientation allows substrate 115 to be transferred to loading cup 122 with a known rotational orientation. Thus, carrier head 210 is able to pick up substrate 115 with a known rotational orientation relative to carrier head 210. For example, pre-aligner 118 may include a reference mark detection system, such as an optical discontinuity sensor (not shown), for sensing when a reference mark is at a specific angular position.

[0032] In some embodiments, the substrate 115 is placed in a metrology station 117 by a dry robot 110 before being placed on the transfer platform 116. For example, the dry robot 110 may transfer the substrate 115 from a pre-aligner 118 to the metrology station 117. The metrology station 117 is used to measure various aspects of the substrate 115. The metrology station 117 may use optical sensors, eddy current sensors, resistance sensors, or other sensors to measure the substrate 115. For example, the metrology station 117 may measure the thickness of an upper layer on the patterned surface of the substrate 115. The controller 190 receives measurement results of the substrate 115 that can be used to facilitate processing of the substrate 115 within the CMP system 100. After measuring the substrate 115 in the metrology station 117, the dry robot 110 may transfer the substrate 115 to the transfer platform 116.

[0033] A wet robot 108 is configured to transfer a substrate 115 from a transfer platform 116 to one of the loading cups 122. A cleaned carrier head 210 moves over the loading cup 122 along with the unpolished substrate 115. The unpolished substrate 115 is then clamped onto the carrier head 210, which then moves to a position on the pad 204 of the polishing station 124 to begin the CMP process.

[0034] Controller 190 controls various aspects of CMP system 100 during CMP processes (e.g., polishing process, polishing operation, polishing). In some embodiments, controller 190 is one or more programmable digital computers executing digital control software. Controller 190 may include a CPU (e.g., processor) 191 located near the polishing equipment, such as a programmable computer, like a personal computer. Controller 190 may include memory 192 and support circuitry 193. For example, controller 190 may coordinate the rotation of polishing pad 204 and carrier head 210 to perform the desired CMP process and facilitate monitoring of the CMP process endpoint. CMP processing system 100 is powered by power supply 180, such as an electrical power source configured to supply power to the components of CMP processing system 100.

[0035] The pressure plate 202 and the bearing head 210 each have a rotation sensor, such as an encoder, to determine the rotational position of the pressure plate 202 and the bearing head 210 during CMP operation. Figure 1 As shown, the pressure plate encoder 195, the first head encoder 196, and the second head encoder 197 are integrated into the controller 190. The pressure plate encoder 195 is configured to determine the rotational (e.g., angular) orientation of the pressure plate 202 and the pad 204. The first head encoder 196 is configured to determine the rotational orientation of each bearing head 210. The second head encoder 197 is configured to determine the position of each bearing head 210 on the polishing pad 204 (e.g., along...). Figure 3A The sweep path 302 of the carrier head 210 in the process. Therefore, the controller 190 is able to determine and track the rotational orientation of the carrier head 210 relative to the pressure plate 202 during the CMP process. In some embodiments, each carrier head 210 has its own dedicated first head encoder 196 and second head encoder 197. In a further embodiment, the controller 190 may use encoders and internal timing elements to calculate the rotational rate of the carrier head 210 and / or pressure plate 202 and polishing pad 204.

[0036] The substrate 115 can be polished in one or more polishing stations 124. For example, the carrier head 210 can pick up the unpolished substrate 115 from the loading cup 122. The carrier head 210 and the substrate 115 clamped to the carrier head 210 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 then undergoes 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 has been polished in the first polishing station 124, 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 can polish the surface of the substrate 115 to form trench lines of a desired height. In some embodiments, the carrier head 210 and the substrate 115 may optionally be transferred from the second polishing station 124 to the third polishing station 124 (e.g., the polishing station 124 in the lower left corner of the polishing module 106) to perform additional polishing on the substrate 115.

[0037] After polishing, the carrier head 210 moves the polished substrate 115, which is clamped to the carrier head 210, onto the loading cup 122, whereby the polished substrate 115 is then placed. The wet robot 108 transports the polished substrate 115 from the loading cup 122 to the cleaning chamber in the cleaner 104, where slurry residue and other contaminants accumulated on the surface of the substrate 115 during polishing are removed. Figure 1 In the embodiments depicted, the cleaner 104 includes two pre-cleaning modules 144, two mega-frequency ultrasonic cleaner modules 146, two brush holder modules 148, two spray modules 150, and two dryers 152. A dry robot 110 then removes the substrate 115 from the cleaner 104. In some embodiments, the dry robot 110 passes the substrate 115 to a metering station 117 for remeasurement. In some embodiments, post-polishing measurements can be used to adjust polishing process parameters for subsequent substrates. Finally, the dry robot 110 returns the substrate 115 to one of the holders 114.

[0038] Figure 2A It shows Figure 1 A schematic cross-sectional view of the polishing station 124 of the CMP system 100. As shown, the polishing station 124 further includes a plurality of endpoint detection sensors 224 and orientation sensors 250. A substrate 115 disposed in the carrier head 210 is illustrated as engaging with a polishing surface 204A of a pad 204 coupled to a pressure plate 202.

[0039] Figure 2BThis is a top view of substrate 115, showing the front surface 230 of substrate 115 bonded to polishing pad 204 during polishing. Front surface 230 includes patterned portions 232 and unpatterned portions 234. Patterned portions 232 (e.g., patterned surfaces) are portions of substrate 115 where multiple semiconductor devices are formed during one or more processes. As shown, the patterned portions 232 are divided into multiple complete grains 233 arranged in a grid pattern. Each grain 233 is a specific semiconductor device being formed on substrate 115. For example, the semiconductor device includes one or more layers formed by one or more processes such as physical vapor deposition (PVD) or atomic layer deposition (ALD).

[0040] The unpatterned portion 234 is the portion of the front surface 230 surrounding the patterned portion 232. The semiconductor device is not formed on the unpatterned surface 234. The unpatterned portion 234 may be exposed to the same processing environment as the patterned portion 232. Material (such as a barrier metal) may be deposited on the unpatterned surface 234 simultaneously with the formation of the semiconductor device on the patterned portion 232. In some embodiments, the unpatterned portion 234 may be a partially patterned portion comprising only a portion, rather than a complete grain. The surface area of ​​the unpatterned portion 234 may be non-uniform around the patterned portion 232. Figure 2B As shown, the surface area of ​​the unpatterned surface 234 varies around the patterned portion 232 depending on its shape. Therefore, some portions of the unpatterned surface 234 have a larger surface area than others.

[0041] The substrate 115 includes a reference mark 236 at the edge of the substrate 115 and therefore at the edge of the unpatterned portion 234. The reference mark 236 is a fixed feature formed on the substrate 115 depending on the doping type and crystal orientation of the substrate 115. Although the reference mark 236 is... Figure 2B The illustration shows a V-shaped notch formed on the edge of substrate 115, but reference numeral 236 can be another feature. For example, reference numeral 236 can be one or more flat edges of substrate 115.

[0042] The substrate 115 has a first line of symmetry 235 passing through the center of the reference mark 236. The unpatterned surface 234 is generally symmetrical about this first line of symmetry 235. Therefore, on either side of the line of symmetry 235, there is a first region 237 adjacent to the reference mark 236, and the first region 237 has substantially the same surface area. Furthermore, on the opposite edge of the substrate 115 from the reference mark 236, there is a similar pair of second regions 238, the second regions 238 having a similar surface area to the first regions 237. Although the unpatterned surface 234 may generally be symmetrical about the first line of symmetry 235, the circuits formed in the individual grains 233 of the patterned surface 232 may be symmetrical or asymmetrical about this first line of symmetry 235.

[0043] See back Figure 2A The polishing pad 204 is secured to the pressure plate 202, such as using an adhesive, such as a pressure-sensitive adhesive (PSA) layer (not shown) disposed between the polishing pad 204 and the pressure plate 202. The carrier head 210 facing the pressure plate 202 and the polishing pad 204 mounted thereon includes a flexible diaphragm 212 configured to apply varying pressure against the back surface of a substrate 115 disposed between the carrier head 210 and the polishing pad 204. This flexible diaphragm 212 is also configured to hold 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 head 210 during polishing. The carrier head 210 rotates about a carrier head axis 216 while the flexible diaphragm 212 rotates over the front surface 230 of the substrate 115. Figure 2B The bearing ring 218 is pressed against the polishing surface 204A of the polishing pad 204. During polishing, the downward pressure on the bearing ring 218 pushes the bearing ring 218 against the polishing pad 204 to improve the uniformity of the polishing process and prevent the substrate 115 from sliding out from under the bearing head 210. In some embodiments, the bearing head 210 includes a shaft 211 having an axis collinear with the bearing head axis 216. In a further embodiment, the pressure plate 202 and the bearing head 210 each have a mechanism or motor (not shown) for driving their rotation.

[0044] In some embodiments, both the pressure plate 202 and the polishing pad 204 rotate about a common pressure plate axis 205. In some embodiments, the polishing pad 204 rotates in the same direction of rotation as the bearing head 210. For example, both the polishing pad 204 and the bearing head 210 rotate counterclockwise. The polishing pad 204 and the bearing head 210 may rotate at the same or different speeds during the polishing operation. Figure 2AAs shown, the polishing pad 204 has a larger surface area than the front surface 230 of the substrate 115. However, in a further embodiment, the polishing pad 204 has a smaller surface area than the front surface 230 of the substrate 115.

[0045] Figure 2A An exemplary embodiment of one of the endpoint detection sensors 224 is also illustrated. Each endpoint detection sensor 224 is radially positioned from the platen axis 205. The endpoint sensor 224 is disposed in a platen opening 226 formed in the platen 202 and below an optically transparent feature 227 (e.g., a window) of the polishing pad 204. The endpoint detection sensor 224 guides light through the platen opening 226 and window 227 at the front surface 230 of the substrate 115 to detect the properties of the front surface 230 during polishing as the endpoint sensor 224 passes under the substrate 115. The controller 190 uses the data collected by the endpoint detection sensor 224 to determine when the endpoint of the CMP process is reached. The endpoint may be, for example, when the desired thickness of the layer formed on the patterned surface 232 is reached. For example, the endpoint may be reached when the metal in the plurality of trench lines formed on the patterned portion 232 reaches the desired thickness.

[0046] Although the endpoint detection sensor 224 is illustrated as an optical sensor, it can be any other suitable sensor capable of monitoring changes in the patterned portion 232 during the CMP process. For example, the endpoint sensor 224 could be an eddy current sensor or an induced current sensor. Eddy current and induced current sensors can be embedded in the pressure plate 202 and / or pad 204, and the transparent feature 227 and opening 226 can be omitted. Although the polishing station 124 is illustrated as having three endpoint detection sensors 224 arranged around the orientation sensor 250, as shown by... Figure 1 The three transparent features 227 in the polishing station 124 are confirmed, but the polishing station 124 may include fewer or more than three endpoint sensors 224.

[0047] Each endpoint detection sensor 224 is positioned at a fixed distance from the rotation center of the pressure plate 202 (e.g., pressure plate axis 205). The pressure plate encoder 195 tracks the rotational position of the pressure plate 202 and the pad 204. The controller 190 is able to determine the position of the endpoint sensor 224 as the pressure plate 202 rotates based on the fixed position of the endpoint sensor 224 and the rotational information obtained from the pressure plate encoder 195.

[0048] Figure 2A The diagram also illustrates the orientation sensor 250. (Regarding...) Figure 3A and Figure 3BAs discussed, the orientation sensor 250 is used to position the reference mark 236 in situ, enabling the controller 190 to determine the rotational orientation of the substrate 115 relative to the carrier head 210 and the pad 204. Since the substrate 115 rotates together with the carrier head 210, the controller 190 is able to correlate the determined position of the reference mark 236 with the rotational orientation of the carrier head 210. The orientation sensor 250 is used to determine the rotational orientation of the substrate 115 after it has been transferred from polishing station 124 to a different polishing station 124. In other words, the substrate 115 does not need to be removed from polishing module 106, passed through cleaner 104, and placed in pre-aligner 118 or metering station 117 to determine its rotational orientation before polishing it on a second or third polishing station 124.

[0049] Knowing the rotational orientation of the substrate 115 and the carrier head 210, as well as the position of each endpoint sensor 224 during polishing, allows the controller 190 to determine which portion of the front surface 230 of the substrate 115 a particular endpoint sensor 224 is scanning. 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.

[0050] The orientation sensor 250 is located at the center of rotation of the pressure plate 202, such that the axis of rotation of the sensor 250 is collinear with the axis of rotation of the pressure plate 205. The endpoint sensor 224 is arranged around the orientation sensor 250 and moves around the axis of rotation of the pressure plate 202 as the pressure plate 202 rotates. To locate the reference mark 236, the bearing head 210 moves to... Figure 2A (See also) Figure 3A The scanning position is shown in the diagram to place the edge of the substrate 115 over 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 substrate 115 to locate the reference mark 236 as the carrier head 210 performs one or more complete revolutions around the carrier head axis 216. In other embodiments, the reference mark 236 is located only after a partial revolution of the carrier head 210.

[0051] In some embodiments, and as Figure 2A As shown, 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 pressure plate 202 and the pad 204. In some embodiments, the orientation sensor 250 is embedded only in the pressure plate 202 and is covered by the pad 204.

[0052] In some embodiments, the layer partially or completely covers the front surface 230, wherein both the patterned portion 232 and the unpatterned portion 234 are fully or partially covered by the layer. This layer may be deposited to form another layer or feature on the grains 233 of the patterned portion 232, which will be polished in a 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 the layer is deposited on both the patterned portion 232 and the unpatterned portion 234. For example, the orientation sensor 250 may obtain data showing that the portion of the layer scanned by the orientation sensor 250 is above the underlying patterned portion 232 or the unpatterned portion 234. In other words, the controller 190 can distinguish between the patterned portion 232 and the unpatterned portion 234, even if both are at least partially obscured by the same layer. Furthermore, the data obtained by the orientation sensor 250 may show variations in the scanned material, such as variations in the area of ​​the unpatterned portion 234, even if the layer fully or partially covers the front surface 230.

[0053] Figure 3A A schematic top plan view of the polishing station 124 is shown to illustrate the carrier head 210 in a scanning position to locate reference mark 236. Adjustment assembly 132 and polishing fluid delivery module 135 are omitted. The head 210 is movable relative to the pad 204 along a sweep path 302 to sweep the substrate 115 along the polishing surface 204A during the polishing process. As the pressure plate 202 rotates, the endpoint sensor 224 crosses the sweep path 302. The endpoint sensor 224 passes beneath the substrate 115 as the carrier head 210 places the substrate 115 at one or more locations along the sweep path 302, which is within the path of travel of the endpoint sensor 224 as the pressure plate 202 rotates.

[0054] The carrier head 210 is illustrated in the scanning position, wherein the edge of the front surface 230 is at least partially positioned above the orientation sensor 250. The carrier head 210 rotates relative to the orientation sensor 250 and the pressure plate 202 while the orientation sensor 250 scans the edge of the substrate 115 to locate the reference mark 236. After the substrate 115 has been transferred from the polishing station 124 in the polishing module 106 to a different polishing station 124, the carrier head 210 moves to the scanning position to allow scanning 310 of the front surface 230 (see Figure 310). Figure 3B To determine the rotational orientation of the substrate 115.

[0055] Figure 3BThe diagram illustrates a scan 310 of the orientation sensor 250 over the front surface 230 of the substrate 115. Scan 310 illustrates the path the orientation sensor 250 travels beneath the front surface 230 to collect data as the carrier head 210 rotates the substrate 115 relative to the orientation sensor 250. Scan 310 is performed near the edge of the front surface 230. Scan 310 is performed close enough to the edge of the substrate 115 that it passes over a portion of the reference mark 236. In some embodiments, when the carrier head 210 is in the scan position, the orientation sensor 250 performs scan 310 only beneath the unpatterned surface 234. Alternatively, the orientation sensor 250 may complete scan 310 along the edge of the substrate 115 that spans both the patterned surface 232 and the unpatterned surface 234.

[0056] Orientation sensor 250 collects data about front surface 230 along scan 310. This data is sent to controller 190 for analysis to determine the position of reference mark 236. First encoder 196 simultaneously records the rotational position of carrier head 210 while orientation sensor 250 collects data along scan 310. Controller 190 correlates the data obtained from orientation sensor 250 with the rotational position of carrier head 210 from which the data was obtained. In other words, controller 190 is able to match the data obtained from orientation sensor 250 with the rotational position of carrier head 210. This allows controller 190 to analyze the data to determine the rotational orientation of reference mark 236 relative to carrier head 210. Once the position of reference mark 236 relative to carrier head 210 is known, the rotational orientation of substrate 115 is known.

[0057] In some embodiments, the carrier head 210 rotates only once about the carrier head axis 216 to allow the orientation sensor 250 to collect enough data along the scan 310 to determine the position of the reference mark 236. In other embodiments, the carrier head 210 rotates more than once to collect enough data along the scan 310 to determine the position of the reference mark 236.

[0058] In some embodiments, both the pressure plate 202 and the carrier head 210 rotate as the orientation sensor 250 scans the substrate 115. In other embodiments, the pressure plate 202 remains stationary while the carrier head 210 rotates to allow the orientation sensor 250 to scan the substrate 115. Once the rotational orientation of the substrate 115 is determined, the controller 190 can cause the pressure plate 202 to begin rotating to initiate the CMP process.

[0059] Figure 4A graph 400 illustrates an exemplary signal 401 of data collected by the orientation sensor 250 as it scans the front side of a rotating substrate 115. This signal 401 illustrates the signal strength at different rotational positions of the carrier head 210. The scanned substrate 115 has a... Figure 2B and Figure 3B The front surface 230 shown is different from the front surface described with respect to the front surface 230. However, the front surface of the scanned substrate 115 has similar characteristics to those described with respect to the front surface 230. Therefore, the same reference numerals will be used to interpret the analysis of signal 401. Furthermore, the signal generated by the orientation sensor 250 will depend on the shape and / or material of the unpatterned portion 234 and the patterned portion 232. Therefore, Figure 4 The signal 401 shown is merely an example of a signal obtained during scanning of the exemplary substrate 115, used to explain how the controller 190 is able to locate the reference mark 236.

[0060] Figure 4 The X-axis of Figure 400 illustrates the rotational position of the bearing head 210. The Y-axis of Figure 400 illustrates the signal strength, expressed in arbitrary units (AU), at the rotational position of the bearing head 210. The signal strength fluctuates across the rotational orientation of the bearing head 210. This is because the signal reflects the properties of the scanned material. In some embodiments, when scanning the material of the unpatterned portion 234, the orientation sensor 250 may record a stronger signal than the material on the patterned portion 232. For example, the orientation sensor 250 may record a stronger signal for the blocking material on the unpatterned surface 234 compared to the material covering the patterned surface 232. Even if the underlying blocking material on the unpatterned portion 234 is partially beneath a layer formed on both the patterned portion 232 and the unpatterned portion 234, a stronger signal may still be recorded. The signal strength may correspond to the size of the area of ​​the unpatterned portion 234 scanned by the orientation sensor 250. In other words, a change in the area of ​​the unpatterned portion 234 results in a change in the signal. For example, the large spike 402 in signal 401 corresponds to a portion of the unpatterned surface 234, which has a larger surface area than the unpatterned surface 234 corresponding to the smaller spike 403. Differences in area variation in the unpatterned portion 234 can be detected even if the front surface 230 is completely or partially covered by a layer. However, for a substrate 115 with a layer formed above the front surface 230, the overall signal strength may be lower or higher than the signal strength obtained when scanning a substrate 115 that does not have a layer that at least partially covers both the patterned portion 232 and the unpatterned portion 234. For example, the signal strength is higher if the layer covering both the patterned portion 232 and the unpatterned portion 234 is composed of a conductive material (such as a metal).

[0061] In some embodiments, signal 401 will typically repeat, such as Figure 4 As shown, this is attributed to the unpatterned surface 234 being symmetrical about the first line of symmetry 235. Therefore, a pattern exists in signal 401, which the controller 190 can analyze to find the position of 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 signal 401 includes determining candidates for the signal portion corresponding to the portion of the substrate 115 that includes reference mark 236. The candidates are then analyzed against a reference mark signature 407 corresponding to reference mark 236. Once the reference mark signature 407 is found, the controller 190 is able to determine the rotational orientation of the substrate 115 relative to the carrier head 210.

[0062] Signal 401 includes a first pair of large spikes 402 (405) and a second pair of large spikes 402 (406). For illustrative purposes, Figure 4 The illustration shows each pair of spikes 405, 406 positioned within the dashed area. In this example, the large spike 402 in signal 401 corresponds to either the first region 237 or the second region 238 of the unpatterned surface 232. Since the surface areas of the first region 237 and the second region 238 are similar, the spikes of the first pair 405 and the second pair 406 have similar signal intensities. Furthermore, a 180-degree rotation of the carrier head 210 (illustrated as D1) exists between the centers of the two pairs of spikes 405, 406. This is expected, as it corresponds to the symmetry of the unpatterned surface 234.

[0063] Each pair of spikes 405 and 406, 402, is a candidate signal corresponding to a portion of the substrate 115 including the reference mark 236. In other words, each pair of spikes 405 and 406 potentially represents a portion of the substrate having a first region 237 with the reference mark 236 located therebetween. The controller 190 is aware that the reference mark 236 is in a rotational position of the carrier head 210 corresponding to one of the candidates. In this case, the reference mark 236 is in the valley between the large spike 402 of one of the first pair of spikes 405 and the second pair of spikes 406. The controller 190 analyzes the candidate signal for the reference mark signature 407. In this example, the substrate 115 being scanned has a notch for the reference mark 236. Signal 401 shows a slight drop between the large spikes 402 of the first pair of spikes 405 compared to the signal between the large spikes 402 of the second pair of spikes 406. This decrease is due to a break (e.g., discontinuity) in the notch within the unpatterned surface 234, resulting in a lower signal strength recorded by the orientation sensor 250 at the rotated position of the carrier head 210. This signal decrease is the reference marker signature 407. The reference marker signature 407 can be detected by comparing a candidate signal to a threshold, such as a threshold signal strength. Thus, if the signal strength reaches or exceeds the threshold signal strength, the reference marker 236 can be identified.

[0064] The controller 190 is able to determine that the notch is between the large spikes 402 of the first pair 405, wherein the center of the large spikes 402 of the second pair 406 is a point on the opposite side of the substrate 115 opposite to 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 in a fixed position on the substrate 115, the controller is able to use the position of the reference mark 236 to determine the rotational orientation of the substrate 115. Furthermore, the controller 190 is able to determine that the point 410 shown in the signal corresponds to a point on an unpatterned surface along the outer edge of the substrate 115 at a 90-degree angle to the reference mark 236.

[0065] In some embodiments, when the reference mark 236 is a flat surface (e.g., a planar portion, a flat edge) rather than a notch, the signal associated with the first region 237 will be different from that of the second region 238 on the opposite side of the substrate. This is because the flat surface results in the first region 237 having a smaller surface area than the second region 238, since the edges of the substrate on the opposite side of the flat surface are rounded. In some embodiments, the controller 190 is able to distinguish the signal obtained from the first region 237 from the signal obtained from the second region 238 based on this difference in surface area.

[0066] Alternatively, scanning the substrate 115, which uses a flat surface as a reference marker, may result in a decrease in signal strength at the reference marker signature 407. As the carrier head 210 rotates the substrate 115 relative to the orientation sensor 250, the orientation sensor 250 may pass along the edge of the flat surface or beyond it. For example, the signal strength may decrease during a period of rotation of the carrier head 210, during which the orientation sensor 250 passes under the front surface 230 and scans blank spaces due to the flat reference marker 236. Once the orientation sensor 250 returns to passing under the front surface 230, the signal strength increases again. Thus, the decrease in signal strength is due to the orientation sensor 250 detecting a lack of material associated with the front surface 230 of the substrate 115. The center of the reference marker 236 may correspond to the center of the decrease in signal strength. In some embodiments, the controller 190 may use the decrease in signal strength between two portions of a signal identified as a candidate for the first region 237 to determine the position of the center of the flat surface relative to the carrier head 210.

[0067] Therefore, controller 190 can analyze the signal 401 obtained from orientation sensor 250 to determine candidate signal portions that comprise the portion of the unpatterned surface 234 including reference mark 236. A candidate signal portion could be a pair of spikes in the signal offset by 180 degrees from another candidate. In other words, controller 190 can identify a pair of candidates on opposite sides of substrate 115. Once a candidate pair is identified, controller 190 can analyze each candidate of reference mark signature 407, such as the decrease in signal strength between the pair of spikes indicating the presence of reference mark 236. Reference mark signature 407 can be determined by comparing two candidates to determine which candidate has the lowest signal strength between the vertices of the spikes.

[0068] In some embodiments, the unpatterned surface 234 of the substrate 115 may have a shape that results in the signal containing two or more pairs of candidates. In other words, other portions of the unpatterned surface 234 may have a surface area similar to the first region 237 and the second region 238. The controller 190 analyzes each pair of candidates to determine which candidate has the reference mark signature 407. The detection of the reference mark signature 407 allows the controller 190 to determine the position of the reference mark 236 relative to the carrier head 210.

[0069] In some embodiments, controller 190 may stop analysis once reference marker signature 407 is found before analyzing all candidates. For example, controller 190 may identify multiple candidates. Controller 190 then analyzes each candidate until reference marker signature 407 is found. Once reference marker signature 407 is found, controller 190 may not analyze the unanalyzed candidates. However, in some embodiments, each candidate is analyzed regardless of whether reference marker signature 407 is found. For example, each candidate may be analyzed to confirm that reference marker signature 407 is not a false positive.

[0070] In some embodiments, the controller 190 locates the reference mark signature 407 by comparing the signal strengths of two or more candidates with a threshold. In other embodiments, the controller 190 is able to determine the position of the reference mark 236 once the threshold is reached or exceeded, without the controller 190 comparing multiple candidates. In other words, the controller 190 is able to locate the reference mark 236 after a portion of the substrate 115 sufficient to locate the reference mark 236 has rotated, and therefore a portion of the carrier head 210 has rotated one full turn.

[0071] In some embodiments, controller 190 locates reference marker signature 407 without recognizing candidates. For example, controller 190 may compare signal 401 to a threshold. When signal 401 reaches or exceeds the threshold, reference marker signature 407 is recognized. As an example, reference marker signature 407 may be a signal strength drop to a signal strength threshold. In some embodiments, controller 190 may compare reference marker signature 407 with other features in the signal to confirm that the location of the reference marker has been identified. For example, controller 190 may compare the location of the reference marker signature with a signature associated with the first region 237.

[0072] In some embodiments, the unpatterned portion 234 is not symmetrical about the line of symmetry. The controller 190 analyzes the signal to a threshold, such as a threshold signal strength, to determine the reference mark signature. For example, the controller 190 may analyze the signal for drops exceeding the signal strength threshold. In some embodiments, the substrate 115 with asymmetrical unpatterned portions may include a region near the reference mark that generates a signal during scanning, which the controller 190 may identify as a candidate for a portion of the substrate including the reference mark. This candidate is then analyzed against the reference mark signature 407.

[0073] CMP system 100 can process one or more types of substrates 115 to perform one or more polishing operations. The shape of the unpatterned surface 234 is substantially consistent across substrates of the same type. As a result, regardless of whether the unpatterned surface 234 is symmetrical about a line of symmetry, the orientation sensor 250 should generate a similar signal for each substrate of the same type. Therefore, each type of substrate may have a reference signal stored in controller 190, the reference signal including a reference signature indicating the position of reference mark 236. The type of substrate 115 may be input to controller 190 so that controller 190 can determine the position of reference mark 236 by comparing the actual signal from orientation sensor 250 with the reference signal.

[0074] Furthermore, the material on the front surface 230 will be consistent because the CMP process will repeat the same desired polishing operation for each type of substrate 115. For example, after polishing the first layer to the desired height at the first polishing station, a scan can be performed at the second polishing station 124 to locate the reference mark 236. Therefore, the orientation sensor 250 should generate similar signals for each substrate of the same type at the same stage of the polishing operation. In addition to the substrate type, the stage of the process can also be input to the controller 190 so that the controller 190 can determine the position of the reference mark 236 by comparing the actual signal from the orientation sensor 250 with a reference signal.

[0075] In some embodiments, the reference signal is a candidate signal, and the reference marker signature is the portion of the candidate signal that satisfies or exceeds a threshold. In some embodiments, the actual signal is superimposed on the reference signal to determine the position of the reference marker. For example, the reference signal may be shifted by several degrees to coarsely align the reference signal with the actual signal to determine the reference marker signature, such as by aligning the reference marker signature 407 with the reference signature of the reference signal.

[0076] During the CMP process, controller 190 uses information collected from pressure plate 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 pressure plate 202. In other words, controller 190 knows the position of the carrier head 210 above the rotating pressure plate 202 at any given time, including knowing the rotational orientation of the carrier head 210 relative to the pressure plate 202. Once controller 190 determines the rotational orientation of the substrate 115 relative to the carrier head 210, controller 190 similarly knows the rotational orientation and position of the substrate 115 relative to the rotating pressure plate 202 and the endpoint sensor 224 at any given time during the polishing process.

[0077] The controller 190 uses the positional information of the substrate 115 and the pressure plate 202 to determine which portions of the front surface 230 are scanned by each endpoint sensor 224 during endpoint analysis. In other words, since the position and rotational orientation of the substrate 115 relative to the head 210 and the pressure plate 202 are known, the controller 190 is able to correlate the data collected by the endpoint sensors 224 with the known positions on the front surface 230. The sweep position of the head 210 relative to the pressure plate 202 and the rotation of both the head 210 and the pressure plate 202 can be coordinated so that each endpoint sensor 224 traverses the same scan path multiple times during the CMP process to scan the same area (e.g., the same region) of the front surface 230. Repeatedly obtaining data from the same area above the substrate improves the signal-to-noise ratio of the data obtained by the endpoint sensors 224, because the endpoint sensors 224 will obtain a consistent signal reflecting the progress of the polishing process over time with each scan. The improved signal-to-noise ratio improves endpoint analysis, thereby allowing for more accurate determination of when the endpoint is reached to produce the desired and uniform polish across the patterned surface 232.

[0078] In conventional CMP processes, the orientation of substrate 115 is unknown after it is passed to the second polishing station 124. As a result, the controller does not know which portions of the substrate are scanned during endpoint analysis because the collected data cannot be correlated with known locations on the substrate surface. Therefore, endpoint analysis in conventional CMP processes is based on random portions of substrate 115 scanned by endpoint sensors. The CMP process disclosed herein (in which endpoint sensor data is correlated with known locations on substrate 115) improves endpoint analysis because the controller 190 and the operator can evaluate the CMP process over time over known areas of the substrate.

[0079] Figure 5 It shows Figure 2B The top view of the substrate 115 shown illustrates exemplary first endpoint scan paths 501, exemplary second endpoint scan paths 502, and exemplary third endpoint scan paths 503 across the front surface 230. Each endpoint scan path 501, 502, 503 corresponds to... Figure 3A The corresponding endpoint sensor 224 (see window 227) of the polishing station 124 shown follows the path it takes as it passes beneath the front surface 230. As shown, each endpoint scan path is arc-shaped due to the movement of the carrier head 210 and the pressure plate 202 during polishing. Each endpoint sensor 224 scans the outer surface multiple times along its corresponding endpoint scan path 501, 502, 503 during the CMP process to facilitate endpoint analysis. Data obtained by the endpoint sensor 224 along its scan path is used during endpoint analysis to determine when the polishing endpoint has been reached. The orientation of the scan paths relative to each other can vary depending on the position of the endpoint sensors 224 relative to each other.

[0080] Furthermore, controller 190 can analyze data obtained at the intersection of scan paths of two or more endpoint sensors 224 to evaluate the endpoint of the CMP process. For example, controller 190 can analyze data obtained at point 511 where the first scan path 501 and the third scan path 503 intersect to analyze the endpoint of the CMP process. This data can be used to plot the trace of the CMP process. Additionally, controller 190 can analyze data obtained at point 512 where the second scan path 502 and the third scan path 503 intersect, and at point 513 where the first scan path 501 and the second scan path 502 intersect, to evaluate the endpoint of the CMP process. Data obtained at each point 511, 512, 513 can be used to plot the separation trace of the endpoint process during endpoint analysis. In some embodiments, controller 190 can also compare data obtained at the intersection of scan paths of two or more endpoint sensors 224 to confirm that the data obtained from each endpoint sensor 224 is consistent.

[0081] The controller 190 can use the position and orientation of the substrate 115 to correlate data obtained by the endpoint sensor 224 with each specific die 233 along the scan path of the endpoint sensor 224. Therefore, the endpoint of the CMP process can be evaluated based on one or more specific dies 233.

[0082] In some embodiments, the positions of the carrier head 210 and the pressure plate 202 may be coordinated such that the endpoint sensor 224 passes under the desired die 233 once or more during the CMP process to evaluate the progress of the CMP process on this specific die 233. In some embodiments, the carrier head 210 and the pressure plate 202 may be coordinated such that the endpoint sensor 224 oscillates along the front surface 230 between different scan paths.

[0083] In some embodiments, the carrier head 210 may be moved to the scanning position once or multiple times during the 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, the controller 190 is able to use the updated orientation during endpoint analysis.

[0084] Figure 6 The illustration shows a trace 600 generated from data acquired from endpoint sensor 224 during the CMP process. This trace 600 can be used during endpoint analysis to determine when the polishing endpoint has been reached. Individual traces 600 can be fabricated for each endpoint sensor 224 to allow evaluation of the CMP process at different points on the substrate surface. For example, the progression of trace 600 can be used to vary the pressure applied to substrate 115 via diaphragm 212 to adjust the polishing rate.

[0085] Signals from endpoint sensor 224 can be sampled to generate one or more measurements 610 for each scan of endpoint sensor 224 across substrate 115. Thus, over multiple scans, the endpoint monitoring system generates a sequence of measurements 610. This sequence of measurements 610 comprises a trace 600. In some embodiments, measurements within a single scan or from multiple scans can be averaged or filtered; for example, a running average can be calculated to produce the measurement 610 for trace 600. For example, each measurement 610 may reflect measurements taken at the intersection of the paths of two or more endpoint sensors at the same area of ​​the front surface 230. The accuracy of trace 600 is increased because endpoint sensor 224 is scanning the same area of ​​the substrate to obtain measurement 610.

[0086] The measurement sequence 610 can be used to determine an endpoint or to determine changes in polishing parameters, for example, to reduce inhomogeneities within the wafer. For example, a function 620 (of the measurement versus time) can be fitted to the measurement 610. Function 620 can be a polynomial function, such as a linear function. The endpoint can be predicted based on the time it takes for the calculated linear function 620 to reach a target value 630. In some embodiments, the endpoint is reached when the trace 600 exceeds a threshold. In some embodiments, the trace can reflect measurements from an endpoint sensor at a specific grain on the substrate surface. Therefore, the endpoint of a specific grain on the substrate can be evaluated during the CMP process.

[0087] Figures 7A to 7D This is a cross-sectional view of substrate 115 at different stages of the CMP process, illustrating an example of a copper CMP process using the CMP system 100 disclosed herein. Figure 7A A patterned portion 732 of a substrate 115 prior to undergoing a CMP process in the first processing station 124 is shown. The substrate 115 includes a dielectric layer 710 having a plurality of trenches 712. A barrier layer 720 is deposited on the dielectric layer 710, and a copper layer 730 is deposited on top of the barrier layer 720. The substrate 115 is transferred from a cassette 114 to a loading cup 122. The substrate 115 is removed from the loading cup 122 by a carrier head 210 and transferred to the first polishing station 124. Before placing the substrate 115 into the loading cup 122, the rotational orientation of the substrate 115 relative to the carrier head 210 can be determined by scanning the substrate 115 with a pre-aligner 118. Therefore, the first polishing station 124 does not have an orientation sensor 250. The substrate 115 is pushed against the polishing pad 204 to polish the upper portion 732 of the copper layer 730, which is deposited on the upper portion 722 of the barrier layer 720, which is deposited on the field 714 of the dielectric layer 710.

[0088] Multiple endpoint sensors 224 at the first polishing station 124 monitor the polishing progress of the copper layer 730. The endpoint sensors 224 can be eddy current sensors, as the copper layer 730 is a continuous layer across the patterned surface 232. The controller 190 evaluates the data obtained via the endpoint sensors 224 to determine when the polishing endpoint of the upper portion 732 of the copper layer 730 is reached, thereby causing the carrier head 210 to lift the substrate from the pad 204 and / or to stop the carrier head 210 and / or the pressure plate 202 from rotating. For example, the endpoint may be reached when the trace reaches a target value corresponding to when the upper portion 732 of the copper layer 730 reaches a desired thickness. This thickness can be selected to avoid complete removal of the upper portion 732 under high downpressure polishing at the first station 124, thereby avoiding excessive surface depression of the copper trench 734. Figure 7B The illustration shows the substrate 115 once the desired thickness of the upper portion 732 of the copper layer 730 is reached.

[0089] The substrate 115 can be polished in a two-station or three-station CMP process. In a two-station copper CMP process, the substrate 115 continues to be polished at the first station 124, but at a much lower downpressure and with a much lower copper removal rate to remove the remaining copper 732 above the upper portion 722 of the barrier layer 720. The controller 190 evaluates data obtained via the endpoint sensor 224 to determine whether the polishing endpoint of the upper portion 732 has been reached to expose the separated copper trenches 734 and the upper portion 722 of the barrier layer 720. The carrier head 210 then moves the substrate to the second polishing station 124 for additional processing. In a three-station copper CMP process, the substrate 115 is moved by the carrier head 210 to the second polishing station 124 to remove the remaining copper above the upper portion 722 of the barrier layer 720. This copper removal process is also monitored by the endpoint sensor 224 equipped on the polishing station 124 to determine when the polishing endpoint has been reached. The carrier head 210 then moves the substrate to the third polishing station 124 for additional processing. Figure 7C The substrate 115 is shown after the copper layer 730 has been removed from the upper portion 722 of the barrier layer 720 in a two-station or three-station copper CMP process.

[0090] In a two-station copper CMP process, a second polishing station 124 and a bearing head 210 are used to polish the pre-surface 230 to achieve the desired height of the copper trench 734, the desired height being... Figure 7C and Figure 7D The diagram shows H1. The desired height H1 is based on the desired resistance of the copper in the trench 734. In other words, the height H1 is selected based on the desired resistance in the circuit formed by the copper trench lines 734. In a three-station copper CMP process, a third polishing station 124 and a carrier head 210 are used to polish the surface before polishing to achieve the desired height H1 of the copper trench 734.

[0091] After the carrier head 210 and substrate 115 are moved to the polishing station 124 for polishing to achieve the height H1 of the copper trench 734, the carrier head 210 is placed in the scanning position to scan the substrate 115 using the orientation sensor 250. The data acquired during the scanning is analyzed to find the position of the reference mark 236 relative to the carrier head 210, which indicates the rotational orientation of the substrate 115 relative to the carrier head 210.

[0092] After the controller 190 determines the rotational orientation of the substrate 115 relative to the carrier head 210, the substrate 115 is polished. Figure 7C and Figure 7DThe illustration shows the progress of the CMP process on the substrate 115 in the second or third processing station 124 after the upper portion 732 has been completely removed to achieve the desired height H1 of the copper trench 734. As the front surface 230 is polished, the upper portion 722 of the barrier layer 720 deposited on the field 714 of the dielectric layer 710 is also removed, as... Figure 7C and Figure 7D The differences are shown in the diagram. The field 714 of dielectric layer 710 can be polished to achieve the desired height H1 of the copper trench 734. As... Figure 7D As shown, the process ends when each of the copper trenches 734 reaches the desired height H1. Each trench 734 is separated from the dielectric layer 710 by the trench portion 724 of the barrier layer 720.

[0093] The endpoint sensor 224 at polishing station 124 monitors the progress of polishing the barrier layer 720 and dielectric layer 710 of substrate 115 to determine when the copper trench 734 reaches the desired height H1. In some embodiments, the endpoint sensor 224 is an induced current sensor configured to monitor the polishing endpoint of the copper trench 734. For example, the endpoint of the polishing process occurring at the second station 124 may be reached when the trace reaches a target value corresponding to the expected copper trench height H1. Once the endpoint is reached, substrate 115 is removed from the second station 124 and returned to cartridge 114 via CMP system 100.

[0094] Figure 8 A flowchart of an exemplary method 800 for processing a substrate is shown. A controller 190 can control each operation of method 800.

[0095] At operation 802, substrate 115 is polished on a first pad 204 of a first pressure plate 202 coupled to a first polishing station 124. One or more endpoint sensors 224 can monitor the polishing endpoint of the front surface 230 of substrate 115.

[0096] At operation 804, the substrate 115 is transferred by the carrier head 210 to the pad 204 of the second polishing station 124. Operation 804 occurs after the first polishing station 124 has completed polishing the substrate 115.

[0097] At operation 806, the carrier head 210 moves to the scanning position to place the edge of the substrate 115 on the orientation sensor 250, which is located at the rotation center of the pressure plate 202 coupled to the pad 204.

[0098] At operation 808, the orientation sensor 250 scans the edge of the substrate 115 to generate a signal. During edge scanning, the bearing head 210 rotates the substrate 115 relative to the pressure plate 202 and the orientation sensor 250.

[0099] At operation 810, 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.

[0100] In some embodiments, operation 810 includes determining one or more candidates from the portion of the signal including the reference marker 236 on the substrate 115. The one or more candidates are then analyzed for a reference marker signature. In some embodiments, the reference marker signature is a decrease in signal strength. In some embodiments, the reference marker signature is identified when the decrease in signal strength reaches or exceeds a threshold.

[0101] In some embodiments, operation 810 includes identifying at least one pair of candidates for portions of the substrate including reference marks positioned 180 degrees apart. Each candidate is then analyzed for reference mark signature.

[0102] In some embodiments, operation 810 includes analyzing a signal to identify a reference mark signature. In some embodiments, the reference mark signature is identified by comparing the signal to a threshold. In some embodiments, the reference mark signature is identified after the carrier head 210 has partially rotated one revolution relative to the orientation sensor 250. In some embodiments, the reference mark signature is identified by comparing the signal to a reference signal from a substrate of the same type.

[0103] At operation 812, the front surface 230 of the substrate 115 is polished within the second polishing station by simultaneously rotating the pad 204 and the support head 210. A diaphragm 212 within the support head 210 pushes 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 acquire data used to determine the endpoint of the polishing process.

[0104] In some embodiments of operation 812, the rotational orientation of the substrate 115 relative to the carrier head 210 is used to determine which portions of the front surface 230 are being scanned along the scan path of each endpoint sensor 224. The movement and rotation of the carrier head 210 and the rotation of the pressure plate 202 can be coordinated such that each endpoint sensor 224 moves multiple times along the same scan path during the polishing process to obtain data of the front surface along the scan path.

[0105] In some embodiments of operation 812, a first grain among a plurality of grains 233 formed on the patterned surface 232 is selected for endpoint analysis. The rotation and position of the bearing head 210 and the rotation of the pressure plate 202 are coordinated to scan the first grain. During the polishing process, the first grain may be scanned once or multiple times.

[0106] In some embodiments of operation 812, the carrier head 210 may be moved to the scanning position once or multiple times 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 changes, the controller 190 is able to perform endpoint analysis using the updated orientation.

[0107] Figure 9 A flowchart of an exemplary method 900 for processing substrate 115 is shown. Controller 190 can control each operation of method 900.

[0108] At operation 902, the orientation sensor 250, located at the rotation center of the pressure plate 202, scans the edge of the substrate 115.

[0109] At operation 904, data obtained by the orientation sensor is used to determine the position of a reference mark on the substrate with respect to the carrier head 210 that engages with (e.g., holds) the substrate 115. In some embodiments, operation 904 includes identifying one or more candidates for portions of the substrate 115 including the reference mark 236, and subsequently performing a signature analysis on each candidate for the reference mark. In some embodiments, operation 904 includes comparing data to a threshold. When the data meets or exceeds the threshold, the position of the reference mark is determined.

[0110] At operation 906, the front surface 230 of the substrate 115 is polished on the pad 204 coupled to the pressure plate 202.

[0111] At operation 908, the endpoint sensor 224 embedded in the pressure plate 202 scans the front surface 230 during operation 906. Data obtained from the endpoint sensor 224 is used to monitor the progress of polishing to determine when the polishing operation has reached its endpoint. The position of reference mark 236 relative to the carrier head 210 is used to identify which portion of the front surface 230 is being scanned by each endpoint sensor. In some embodiments, each endpoint sensor scans the same portion of the front surface 230 multiple times during the polishing operation. For example, the position and rotation of the carrier head 210 and the rotation of the pressure plate 202 can be coordinated such that each endpoint sensor 224 repeatedly travels along the same scanning path relative to the front surface 230 of the substrate 115, which has a known rotational orientation relative to the carrier head 210.

[0112] Although the foregoing relates to embodiments of the present disclosure, other and further embodiments of the present disclosure may be conceived without departing from the basic scope of the present disclosure, the scope of which is defined by the appended claims.

Claims

1. A method for processing a substrate, comprising the following steps: Polish the front surface of the substrate on the first pad coupled to the first pressure plate; The substrate is transferred from the first pad to the second pad coupled to the second pressure plate using a carrier head; The carrier head is moved to the scanning position to place the edge of the substrate on the orientation sensor, which is located at the rotation center of the second pad; The orientation sensor is used to scan the edge of the substrate to generate a signal; as well as The signal is analyzed to locate the reference mark on the substrate in order to determine the rotational orientation of the substrate relative to the carrier head.

2. The method of claim 1, wherein the reference mark is a notch or a flat surface formed in the edge of the substrate.

3. The method of claim 1, wherein the step of analyzing the signal to locate the reference marker includes the following steps: Identify one or more candidates for the portion of the substrate that includes the reference mark; as well as The one or more candidates are analyzed for the reference tag signature.

4. The method of claim 3, wherein the reference marker signature is a decrease in the strength of the signal.

5. The method of claim 4, wherein the reference marker signature is identified by the decrease in signal strength reaching or exceeding a threshold.

6. The method of claim 1, wherein the step of analyzing the signal to locate the reference marker includes the following steps: For the portion of the substrate including the reference marks positioned 180 degrees apart, at least one pair of candidates is identified; as well as Each candidate in the pair of candidates is analyzed for reference token signature.

7. The method of claim 1, wherein the step of analyzing the signal to locate the reference marker includes the following steps: Identify reference marker signatures.

8. The method of claim 7, wherein the reference mark signature is identified by comparing the signal with a threshold or a pre-stored reference signal signature of the reference mark of the type substrate.

9. The method of claim 7, wherein the reference mark signature is identified after the portion of the carrier head has rotated one revolution.

10. The method of claim 1, further comprising the following steps: The front surface is polished by rotating the second pad and the bearing head; and Multiple endpoint sensors are used to monitor the front surface to determine the endpoint of polishing the front surface through the second pad.

11. The method of claim 10, wherein the step of monitoring the front surface comprises the following steps: The determined rotational orientation of the substrate relative to the carrier head is used to determine which portion of the front surface is being scanned by each endpoint sensor.

12. The method of claim 10, wherein the step of monitoring the front surface comprises the following steps: Each endpoint sensor is moved multiple times along the scanning path along the front surface to obtain endpoint data of the front surface along the scanning path.

13. The method of claim 10, wherein the step of monitoring the front surface comprises the following steps: Select the first grain among the plurality of grains formed on the front surface; and The rotation and position of the bearing head and the rotation of the second pressure plate are coordinated to scan the first grain.

14. A method for polishing a substrate, comprising the following steps: The edge of the substrate is scanned using an orientation sensor positioned at the rotation center of the pressure plate; The data obtained through the orientation sensor is analyzed to determine the position of the reference mark on the substrate relative to the bearing head that holds the substrate. Polish the front surface of the substrate; as well as During polishing, the front surface is monitored using an endpoint sensor embedded in the pressure plate that scans the front surface, wherein the monitoring step includes the following steps: using the reference mark with respect to the determined position of the bearing head to identify the portion of the front surface being scanned by the endpoint sensor.

15. The method of claim 14, wherein the step of analyzing the data obtained by the orientation sensor to determine the position of the reference mark with respect to the carrier head includes the following steps: One or more candidates are identified for a portion of the substrate including the reference marks positioned at intervals of several degrees; as well as Each candidate is analyzed based on the reference tag signature.

16. The method of claim 14, wherein the step of analyzing the data obtained by the orientation sensor to determine the position of the reference mark with respect to the carrier head includes the following steps: The data is compared with a threshold, wherein the position of the reference marker is determined when the threshold is met or exceeded.

17. The method of claim 14, wherein the monitoring step comprises the following steps: During the polishing of the front surface, the identification portion of the front surface is scanned multiple times using the endpoint sensor.

18. A polishing system comprising: Polishing station, the polishing station comprising: A pressure plate, the pressure plate including a polishing pad; A carrier head, which is configured to rotate a substrate; An orientation sensor is embedded in the pressure plate at the rotation center of the pressure plate, wherein the orientation sensor is configured to scan the edge of the substrate including a reference mark; Multiple endpoint sensors are embedded in the pressure plate around the orientation sensor, each endpoint sensor being configured to monitor the surface of the substrate being polished on the pad; as well as A controller that communicates with the orientation sensor and the endpoint sensor, wherein the controller is configured to analyze data obtained by the orientation sensor to identify the position of the reference marker relative to the carrier head.

19. The polishing system of claim 18, wherein the orientation sensor is an isotropic electromagnetic sensor.

20. The polishing system of claim 18, further comprising: At least one of a measuring tool or a pre-alignment station, the measuring tool or the pre-alignment station being configured to determine the position of the reference mark before polishing the substrate.

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