Control of Pad Shape in Chemical Mechanical Polishing

Abstract

A chemical mechanical polishing apparatus includes a platen that supports a polishing pad, an actuator, a carrier head that holds the surface of a substrate against the polishing pad, and a motor that generates relative movement between the platen and the carrier head to polish an upper layer on the substrate. The platen has a central portion having an upper surface, and an annular flexure portion that surrounds the central portion or is surrounded by the central portion, the annular flexure portion having a top surface having a first edge adjacent to and in the same plane as the upper surface and a second edge remote from the central portion. The actuator is arranged to bend the annular flexure portion along the entire circumference of the annular flexure portion to correct the vertical position of the second edge of the annular flexure portion relative to the central portion.

Description

Technical Field

[0001]

[0001] This disclosure relates to chemical mechanical polishing, and more specifically, to the control of the platen shape in chemical mechanical polishing.

Background Art

[0002]

[0002] Integrated circuits are typically formed on a substrate by sequentially depositing conductive, semiconductive, or insulating layers on a silicon wafer. A manufacturing step includes depositing a fill layer on a non-planar surface and planarizing the fill layer. In certain applications, the fill layer is planarized until the top surface of the patterned layer is exposed. For example, a conductive fill layer can be deposited on a patterned insulating layer to fill trenches or holes in the insulating layer. After planarization, the portions of the metal layer remaining between the raised patterns of the insulating layer form vias, plugs, and lines that serve as conductive paths between thin film circuits on the substrate. In other applications such as oxide polishing, for example, the fill layer is planarized by polishing for a predetermined time, leaving a portion of the fill layer on the non-planar surface. Further, in photolithography, planarization of the substrate surface is typically required.

[0003]

[0003] One problem in CMP is the variation in the material removal rate of the substrate and the subsequent thickness profile. Variations in slurry distribution, the condition of the polishing pad, the relative speed between the polishing pad and the substrate, and the inconsistent load applied from the carrier head's pressure chamber to the substrate can cause variations in the material removal rate. These variations, like the variations in the initial thickness of the substrate layer, can cause variations in the final thickness of the substrate layer, particularly in the edge region.

Summary of the Invention

[0004]

[0004] Disclosed herein is a chemical mechanical polishing apparatus including an annular flexure portion in one or more regions of a platen that supports a polishing pad. The annular flexure portion is controlled to vertically deflect an outer edge. A carrier head can move a portion of a substrate onto the deflected outer edge to locally increase or decrease a polishing rate and reduce polishing non-uniformity in a polished substrate. A controller of the apparatus instructs displacement or positioning of the annular flexure portion through an actuator supported by the platen.

[0005]

[0005] The apparatus includes an in-situ monitoring system such as an optical monitoring system that receives a signal indicating a radial thickness profile of an upper layer of a material on a substrate. The controller processes the signal and determines whether additional polishing is required in an annular region of the substrate, for example, an annular region at an edge of the substrate. If additional polishing is required, the controller causes the actuator to deflect the annular flexure portion upward, while if polishing is less necessary, the controller causes the actuator to deflect the annular flexure portion downward. The carrier head moves a portion of the substrate onto the deflected region for additional polishing.

[0006]

[0006] The carrier head moves away from the deflected annular region of the substrate and the thickness profile is re-determined. If the thickness profile is within a uniformity threshold, additional polishing can be performed (if necessary) without using the annular flexure region. If the thickness profile does not meet the uniformity threshold, the controller determines that additional polishing on the annular flexure portion is required.

[0007]

[0007] In one aspect, a chemical mechanical polishing apparatus includes a platen that supports a polishing pad, an actuator, a carrier head that holds the surface of a substrate against the polishing pad, and a motor that generates relative movement between the platen and the carrier head to polish an upper layer on the substrate. The platen has a central portion having an upper surface, and an annular flexure portion that surrounds the central portion or is surrounded by the central portion, the annular flexure portion having a top surface with a first edge adjacent to and in the same plane as the upper surface and a second edge spaced from the central portion. The actuator is arranged to bend the annular flexure portion along the entire circumference of the annular flexure portion to correct the vertical position of the second edge of the annular flexure portion relative to the central portion.

[0008]

[0008] Implementation aspects may include one or more of the following features. The annular flexure portion may be surrounded by the central portion of the platen and have an outer edge adjacent to and in the same plane as the upper surface and an inner edge spaced from the central portion, and the actuator may be arranged to correct the vertical position of the inner edge. The annular flexure portion may be 25% or less of the innermost radius of the platen. The in-situ monitoring system may include a sensor head supported by the platen such that the sensor head passes below the carrier head and receives an optical signal from a substrate held by the carrier head. The thickness of the flexure portion may be substantially equal to the thickness of the platen at the central portion. The annular seal may be positioned at the outer edge of the annular flexure portion.

[0009]

[0009] In another aspect, a method of polishing a substrate includes supporting a polishing pad with a rotatable platen, the platen including at least one annular flexure portion extending from a central region of the platen and an actuator supported by the platen configured to adjust the vertical height of an edge of the annular flexure portion relative to the central region along the entire circumference of the annular flexure portion; positioning the substrate such that a portion of the substrate is over the annular flexure portion and an annular region of the substrate moves over the annular portion; and generating relative movement between the polishing pad and the substrate to polish an upper layer on the substrate.

[0010]

[0010] In another aspect, the chemical mechanical polishing apparatus includes a platen that supports a polishing pad, a carrier head that holds the surface of a substrate against the polishing pad, and a motor that generates relative movement between the platen and the carrier head to polish an upper layer on the substrate. The platen has a central portion with an upper surface and an annular flexure portion that surrounds or is surrounded by the central portion. The annular flexure portion has a top surface having a first edge adjacent to and in the same plane as the upper surface and a second edge remote from the central portion. The annular flexure portion is tapered so as to become thinner toward the second edge. The actuator is arranged to bend the annular flexure portion to correct the vertical position of the second edge of the annular flexure portion relative to the central portion.

[0011]

[0011] In another aspect, the chemical mechanical polishing apparatus includes a platen that supports a polishing pad, a carrier head that holds the surface of a substrate against the polishing pad, and a motor that generates relative movement between the platen and the carrier head to polish an upper layer on the substrate. The platen has an upper portion and a lower portion, and the upper portion has a central portion with an upper surface. The annular flexure portion surrounds or is surrounded by the central portion and has a top surface having a first edge adjacent to and in the same plane as the upper surface and a second edge remote from the central portion. The pressurizable chamber between the upper platen and the lower platen is configured to bend the annular flexure portion by changing the pressure in the chamber to correct the vertical position of the second edge of the annular flexure portion.

[0012]

[0012] In another aspect, the chemical mechanical polishing apparatus includes a platen having a lower platen and an upper platen that supports a polishing pad, a carrier head that holds the surface of the substrate against the polishing pad, and a motor that generates relative movement between the platen and the carrier head to polish the upper layer on the substrate. The upper platen has a central portion movable in the vertical direction and an annular outer portion that surrounds the central portion and is coupled to the central portion by an annular bendable portion. The outer edge of the annular outer portion is supported by the lower platen and is fixed perpendicular to the lower platen. The actuator is arranged to correct the inclination of the annular outer portion by adjusting the vertical positions of the central portion and the inner edge of the annular outer portion.

[0013]

[0013] The implementation aspect may include one or more of the following features. The annular bendable portion may be provided by an annular recess formed on the lower surface of the upper platen. The central portion may be tapered to become thinner toward the annular outer portion. The annular outer portion may be tapered to become thinner toward the central portion.

[0014]

[0014] Certain implementation aspects of the subject matter described in this specification may be implemented to achieve one or more of the following technical advantages.

[0015]

[0015] Radially specialized thickness profile correction can be performed to reduce within-wafer non-uniformity and between-wafer non-uniformity. By material removal, the non-uniformity of the thickness profile in the edge region induced after the main polishing step can be compensated, or the thickness profile of the substrate film before undergoing the main polishing can be corrected. The amount of deflection (e.g., displacement from the planar configuration) due to the annular flexure portion leads to a change in the pressure applied to the substrate surface rather than through the back side of the substrate, increasing the polishing position specificity during position-specific polishing. The dimensions of the pressure increase region may be small compared to the surface area of the entire substrate and can be controlled by the positioning of the substrate by the carrier head, enabling material removal in a highly specific region.

[0016] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from the description and drawings, and from the claims.

Brief Description of the Drawings

[0017]

Figure 1

Figures 2A-2B

Figures 3A-3C

Figures 4A-4B

Figure 5

Best Mode for Carrying Out the Invention

[0018]

[0022] In the figures, like references indicate like elements.

[0019]

[0023] In some chemical mechanical polishing processes, portions of the substrate may be underpolished or overpolished. In particular, at or near the edge of the substrate, the substrate tends to be overpolished or underpolished. As one technique for addressing such polishing non-uniformities, there is a method of providing a plurality of controllable pressurizable chambers in the carrier head. However, the pressure applied from the back side of the substrate tends to "spread", and it may be difficult to correct for radially localized pressure. As another technique, there is a method of transferring the substrate to another "touch-up" tool, for example, to perform edge correction. However, the additional tool consumes valuable floor space in the clean room and may have an adverse effect on throughput.

[0020]

[0024] An alternative approach is to provide a platen having independently controllable annular flexures that can be deflected, for example, upwardly or downwardly. Then, as a result of moving a portion of the substrate onto the deflected flexure, the pressure between the polishing pad and the substrate increases or decreases at that portion, and as a result, it becomes possible to perform radially focused polishing of the edge portion of the substrate.

[0021]

[0025] Several approaches for adjustable platens have been proposed, but such systems are not known to be commercialized and are generally expected to cause other problems. For example, in a system having vertically adjustable concentric platens, the vertical displacement between the platens can cause height discontinuities and there is a risk of damaging the substrate.

[0022]

[0026] FIG. 1 shows a polishing system 20 operable to polish a substrate 10. The polishing system 20 includes a rotatable platen 24 on which a main polishing pad 30 is disposed. The platen is operable to rotate about a rotation axis 25. For example, a motor 21 can rotate a drive shaft 22 to rotate the platen 24. In some implementations, the platen 24 includes a central portion 26 configured to provide an annular upper surface 28 that supports the main polishing pad 30.

[0023]

[0027] The main polishing pad 30 can be fixed to the upper surface 28 of the central portion 26 of the platen 24, for example, by an adhesive layer. When worn, the main polishing pad 30 can be removed and replaced. The main polishing pad 30 can be a two-layer polishing pad having an outer polishing layer 32 with a polishing surface and a softer backing layer 34.

[0024]

[0028] The polishing system 20 may include a pad cleaning system such as a polishing liquid delivery arm 39 and / or a rinse liquid delivery arm. During polishing, the arm 39 is operable to dispense a polishing liquid 38, such as a slurry having abrasive particles. In some implementations, the polishing system 20 includes a composite slurry / rinse arm. Alternatively, the polishing system may include ports within the platen operable to dispense the polishing liquid 38 onto the main polishing pad 30. The polishing system 20 may also include a conditioner system 40 having a rotatable conditioner head 42, which may include a polishing lower surface on a removable conditioning disk, for example, to condition the polishing surface 36 of the main polishing pad 30.

[0025]

[0029] The polishing system 20 includes a carrier head 70 operable to hold the substrate 10 against the main polishing pad 30. The carrier head 70 is suspended from a support structure 72, such as a carousel or a track, for example, and is connected to a carrier head rotation motor 76 by a carrier drive shaft 74, so that the carrier head can rotate about the axis 71. Further, the carrier head 70 can swing laterally across the polishing pad by being driven, for example, by an actuator to move within a radial slot of the carousel, or by the rotation of the motor-driven carousel, or by being driven by an actuator to move back and forth along the track. During the process, the platen 24 rotates about its central rotation axis 25, the carrier head rotates about its central axis 71, and translates laterally parallel across the top surface of the polishing pad.

[0026]

[0030] The carrier head 70 may include a retaining ring 73 for holding the substrate 10 below the flexible membrane 144. The carrier head 70 may also include one or more independently controllable pressurizable chambers, such as three chambers 77a - 77c, defined by a membrane that can apply independently controllable pressure to associated zones on the flexible membrane 144 and thus on the substrate 10. Only three chambers are shown in FIG. 1 for ease of illustration, but there may be one or two chambers, or four or more chambers, such as five chambers.

[0027]

[0031] A controller 90, such as a programmable computer, is connected to the motors 21, 76 to control the rotational speeds of the platen 24 and the carrier head 70. For example, each motor may include an encoder that measures the rotational speed of the associated drive shaft. A feedback control circuit, which may be in the motor itself, part of the controller, or a separate circuit, receives the measured rotational speed from the encoder and adjusts the current supplied to the motor so that the rotational speed of the drive shaft matches the rotational speed received from the controller.

[0028]

[0032] The polishing system 20 also includes at least one annular flexure 50 fixed to the platen 24 and rotating with the platen 24. A portion of the polishing pad 30 supported on the platen 24 extends above the flexure 50. The flexure 50 is deformable by one or more actuators 52. The polishing system 20 may include an annular flexure 50a that projects outwardly from the outer edge of the platen 24. Alternatively, if the platen 24 itself is annular, the polishing system may include an annular flexure 50b that projects inwardly from the inner edge of the annular platen 24. Or, there may be two flexures, for example, one for the outer edge of the platen 24 and the other for the inner edge, namely flexure 50a and flexure 50b.

[0029]

[0033] When the annular flexure portion 50 flexes upward, the outer portion limited in the radial direction of the polishing pad 30 is urged upward. When a part of the substrate 10 exists on the flexure portion, the pressure on that part increases. Conversely, when the annular flexure portion 50 flexes downward, the outer portion limited in the radial direction of the polishing pad 30 is urged downward. When a part of the substrate 10 exists on the flexure portion, the pressure on that part decreases. The terms "upward" and "downward" used herein relate to the orientation of FIG. 1. Upward refers to the direction from the platen 24 to the polishing pad 30 and then to the substrate 10, and downward refers to the reverse. In the process, the polishing surface can be oriented perpendicular to gravity or in other directions.

[0030]

[0034] The annular flexure portion 50 extends a distance in the range of 5% to 20% of the radius of the polishing pad 30 (for example, 5% to 15%, 5% to 10%, 10% to 15%, or 15% to 20%) from the outer edge of the platen 24.

[0031]

[0035] In some implementations, the polishing apparatus includes an in-situ monitoring system 160, such as an optical monitoring system, such as a spectroscopic monitoring system, that can be used to measure the spectrum of reflected light from the substrate during polishing. The monitoring system 160 may include a sensor supported on the platen, such as the ends of optical fibers coupled to a light source 162 and a photodetector 164. As the platen rotates and the sensor moves below the carrier head 70 and the substrate 10, the monitoring system 160 receives measurements at a sampling frequency such that the measurements are taken at positions along an arc across the substrate 10. From the measurements, the in-situ monitoring system 160 generates a signal that depends on the thickness of the layer of material being polished, such as a thickness profile. Additionally or alternatively, the in-situ monitoring system 160 generates a signal that depends on the polishing rate of the layer of material being polished, such as a polishing rate profile.

[0032]

[0036] The controller 90 receives a signal, converts the signal into a process profile, such as a thickness profile or a polishing rate profile, and compares the process profile with a target profile. For example, the target profile may be a predetermined target thickness profile for the thickness depending on the radial direction of the layer at the end of polishing, or a target polishing rate profile storing a target polishing rate depending on the radial direction during polishing. The process profile may be based on the radial width of the substrate 10 or a measurement value over a part of the radial width of the substrate 10. In some implementations, the controller 90 calculates the process profile of the portion of the substrate 10 corresponding to the outermost annular region of the substrate 10, such as the outermost 5%, outermost 10%, or outermost 20% of the substrate 10.

[0033]

[0037] The controller 90 compares the process profile with the target profile. When the difference between the process profile and the target profile exceeds a threshold value, the controller 90 determines to change the polishing parameters. When the difference occurs in a region of the substrate that can be controlled by the deflector, for example, in the outermost annular region adjacent to the edge of the substrate 10, the deflector can be used to compensate for the deviation of the process profile from the target profile.

[0034]

[0038] When the polishing rate of a region of the substrate exceeds the target polishing rate, the controller 90 can determine to position the region on the deflector and deflect the deflector downward. The downward deflection reduces the polishing rate of that region and achieves the target polishing rate profile. When the polishing rate of that region of the substrate is lower than the target polishing rate of that region, the controller 90 can determine to position the region on the deflector and deflect the deflector upward to increase the polishing rate of that region.

[0035]

[0039] As shown in the embodiment of FIG. 1, the polishing system 20 includes an annular flexure 50 that projects radially outward from the central portion 26 of the platen 24. When not deflected or deformed, the top surface of the annular flexure 50 is substantially coplanar with the upper surface 28 of the platen 24. The inner edge of the annular flexure 50 is fixed to the platen 24 and is rotatable with the platen 24. Thus, when the drive shaft 22 rotates the platen 24, the annular flexure 50 rotates with the platen 24 (thus, the annular flexure 50 does not require a separate motor for rotation).

[0036]

[0040] The annular flexure 50 is connected to at least one actuator 52 arranged to be supported by the central portion 26 of the platen 24. In some implementations, such as the embodiment of FIG. 1, the actuator 52 is arranged to apply a substantially lateral force to the flange 54. The flange 54 projects downward from the outer edge of the annular flexure 50. In such an implementation, the actuator 52 applies an inward force (e.g., a force towards the axis of rotation 25) or an outward force (e.g., a force away from the axis of rotation 25). The system 20 includes a sufficient number of actuators 52 to control the outer edge of the annular flexure 50 around the platen 24. The system 20 may include two or more, four or more, or eight or more actuators 52. When there are multiple actuators, the actuators may be arranged at uniform angular intervals about the axis of rotation 25 of the platen 24.

[0037]

[0041] When the actuator 52 applies an inward force, the outer edge of the top surface of the annular flexure 50 deflects downward. Conversely, when the actuator 52 applies an outward force, the outer edge of the top surface of the annular flexure 50 deflects upward. The controller 90 controls the actuator 52 to adjust the force applied to the flange 54 and controls the outer edge of the top surface of the annular flexure 50 to deflect upward or downward.

[0038]

[0042] The system can be configured such that the annular flexure portion 50 flexes along the entire circumference of the flexure portion 50. In some implementations, there is a single actuator, and the flexure portion 50 has sufficient rigidity along an angle at which the pressure from the actuator in a limited area causes the flexure portion 50 to flex along the entire circumference. In some implementations, there are multiple actuators, and the actuators are electrically connected to a single control signal such that all the actuators are driven integrally. In some implementations, each actuator 52 can be individually controlled by a controller 90, but the controller 90 controls all of the actuators 52 to cause the annular flexure portion 50 to flex along the entire circumference.

[0039]

[0043] In many polishing processes, due to the reduced pressure control in the outermost radial regions of the three chambers 77a - 77c, the outer edge of the substrate 10 is under-polished, and as a result, the layer thickness at the edge of the substrate 10 increases. Therefore, the annular flexure portion 50 is flexed upward to bias it with respect to the bottom surface of the substrate 10, increasing the pressure between the substrate 10 and the polishing pad 30.

[0040]

[0044] The controller 90 operates the actuator 52 to change the position of the outer edge of the annular flexure portion 50 upward or downward by a certain distance. In some implementations, the distance ranges from 1 micron to 300 microns (e.g., from 1 micron to 250 microns, from 10 microns to 250 microns, from 50 microns to 250 microns, from 10 microns to 50 microns, or from 1 micron to 50 microns).

[0041]

[0045] Throughout this location and the entire specification, references to measurable values such as amounts, time durations, etc. should be considered as disclosures of exact values, approximate values, and surrounding values, for example, disclosures within ±10% of the value. For example, a reference to 100 microns here can be considered as a reference to either exactly 100 microns, approximately 100 microns, or within ±10% of 100 microns.

[0042]

[0046] In some implementations, the annular platen 24 includes a recess 27 that is centered on the platen 24 and extends partially through the thickness of the platen 24 and is aligned with the axis of rotation 25. For example, the recess 27 may be circular, and the center of the recess 27 may be coaxial with the axis of rotation 25. In some implementations, the recess 27 extends through the entire thickness of the platen 24.

[0043]

[0047] The recess houses a central annular flexure 51 that includes a flange 54 and one or more actuators 52 for applying a force to the flange 54. The inner edge of the central annular flexure 51 (e.g., the edge closest to the axis of rotation 25) flexes upward or downward based on the force applied to the flange 54 by the actuator 52, and the outer edge of the central annular flexure 51 remains substantially in the same plane as the upper surface 28.

[0044]

[0048] The central annular flexure 51 extends a distance from the inner edge of the platen 24 in the range of 5% to 25% (e.g., 5% to 15%, 5% to 10%, 10% to 25%, or 15% to 25%) of the innermost radius of the polishing pad 30.

[0045]

[0049] The arrangement of the actuator 52, the outer annular flexure 50a, and the central annular flexure 50b defines a region of the pad 30 where the pressure between the pad 30 and the substrate 10 is at least partially controlled by the amount of flexure provided by the actuator 52. Refer to FIGS. 2A and 2B, which show top views of the polishing pad 30 and the substrate 10 and schematically show a particular polishing region. FIG. 2A shows an implementation where the apparatus 100 includes only the outer annular flexure 50a, and FIG. 2B shows an implementation where the apparatus 100 includes both the outer annular flexure 50a and the central annular flexure 50b. The holding ring 73 surrounds the substrate 10 within the apparatus 100 during the polishing process, but this component is visually removed in FIGS. 2A and 2B for simplicity.

[0046]

[0050] Referring to FIGS. 1 and 2A, there is shown a top view of a pad 30 and a substrate 10 supported by a platen 24, where the system 20 includes only the outer annular flexure 50a. The central portion 26 of the platen 24 supports the central region 31 of the pad 30. The annular flexure 50a is disposed around the platen 24 and supports the outer region 33. The outer edge of the outer region 33 flexes upward or downward, and the inner edge of the outer region 33 remains substantially in the same plane as the central region 31.

[0047]

[0051] The substrate 10 is moved by a carrier head 70 such that a portion 12 of the substrate 10 is located above the outer region 33. Depending on whether the flexure 50a is biased upward or downward, the pressure on the portion 12 of the substrate 10 in the outer region 33 increases or decreases. Due to the rotation of the carrier head 70 and the substrate 10 (shown by arrow A), the annular portion 12a of the substrate 10 has an increased or decreased polishing rate (compared to the case where the flexure remains planar).

[0048]

[0052] Referring to FIGS. 1 and 2B, there is shown a top view of a pad 30 and a substrate 10 supported by a platen 24, where the system 20 includes an annular flexure 50 and a central annular flexure 50b. The central annular flexure 50b defines the inner region 35 of the polishing pad 30, and the outer annular flexure 50a defines the outer region 33. The polishing pad 30 supported by the central portion 26 that remains substantially planar during polishing is defined as the central region 31. In this way, the outer region 33 and the inner region 35 define two regions that can change the pressure between the substrate 10 and the polishing pad 30.

[0049]

[0053] When the substrate 10 is passed over the inner region 35 by a carrier head 70 (not shown), a portion 13 of the substrate 10 overlaps the inner region 35. When the inner region 35 is deflected upward or downward by the central annular deflection portion 51, the portion 13 is subjected to increased or decreased pressure. Again, due to the rotation of the carrier head 70 and the substrate 10 (indicated by arrow A), the polishing rate of the annular portion 13a of the substrate 10 increases or decreases. In the embodiments of FIGS. 2A and 2B, assuming that the substrate edge is under-polished, in order to compensate for this, the polishing rates of portions 12 and 13 of the substrate 10 overlapping the inner region 35 and the outer region 33 are increased, and the uniformity within the wafer and between wafers can be improved.

[0050]

[0054] The carrier head 70 passes over the central region 31 of the substrate 10, and the optical monitoring system 160 receives a signal indicating the updated thickness of the upper layer of the material, for example, the updated thickness profile, and calculates a new uniformity value of the updated thickness profile.

[0051]

[0055] The controller 90 compares the updated uniformity value with a uniformity threshold. When the uniformity value is below the uniformity threshold, the controller 90 determines not to continue increasing the polishing of the region of the substrate 10 corresponding to the region exceeding the uniformity threshold.

[0052]

[0056] FIGS. 3A to 3C show exemplary implementations for achieving the deflection of the edge portion of the platen 324 that can provide the platen 24. In the implementations of FIGS. 3A to 3C, the platen 324 includes a lower platen 310 and an upper platen 312. The upper platen 312 supports the polishing pad 30 and is supported by the lower platen 310. The upper platen 312 is made of a material having sufficient flexibility to achieve the deflection distance of the annular deflection portion 50, while having sufficient durability and non-compressibility to be suitable for the polishing process. In some embodiments, the upper platen 312 is made of a polymer material or a metal material such as aluminum.

[0053]

[0057] The upper platen 312 includes a tapered region 350 that can provide the flexure portion 50. In the case of the outer annular flexure portion 50a, the tapered region may be the annular outer region 316 of the upper platen 312, and in the case of the inner annular flexure portion 50b, the tapered region may be the annular inner region of the upper platen 312. The tapered region 350 may have a reduced thickness compared to the inner central region 314. Further, the tapered region 350 is tapered to a minimum edge thickness at the outer edge of the outer region 316 (or the inner edge of the inner region). The embodiment of FIG. 3A uses an annular flange 354 and an actuator 356 spaced radially apart to apply a force to the flange 354 to flex the tapered region 350 of the upper platen 312. The flange 354 may be integral with the tapered region 350 of the upper platen 312, or the flange 354 may be a separate manufactured article attached to the tapered region 350. Due to the tapering, the edges of the tapered region are more flexible and thus more easily deflected. The taper reduces the force required to deform that portion, and as a result, reduces the stress induced in the upper platen.

[0054]

[0058] The embodiment of FIG. 3B uses adjustment screws 362 spaced radially around the upper platen 312 to apply a force to the flange 354, for example, in a horizontal direction within the plane of the upper platen 312. Each adjustment screw 362 passes through an aperture 329 extending through each flange 354.

[0055]

[0059] In some implementations, the upper platen 312 includes a rotary actuator 364 connected to the adjustment screw 362. The controller 90 controls the rotary actuator 364 to translate the adjustment screw 362 inwardly, for example, toward the central axis 125, or outwardly, for example, away from the central axis 125. Based on the inward or outward translational movement of the adjustment screw 362, the force applied within the plane of the upper platen 312 deflects the tapered region 350 downward or upward. The screw can provide a mechanical advantage in that the rotation of the screw can generate a large force in a linear direction.

[0056]

[0060] Alternatively, the upper platen 312 includes a static screw recess aligned with the aperture 329 such that an adjustment screw 362 extending through the flange 354 is manually driven or retracted into the upper platen 312 to adjust the degree of deflection of the tapered region 350.

[0057]

[0061] In the embodiment of FIG. 3C, an annular void 372 between the tapered region 350 and the platen 310 is sealed against gas flow by an annular seal 374. The platen 310 includes a channel 376 fluidly connecting the void 372 to a gas pressurization system 378. The gas pressurization system 378 operates to vary the gas pressure in the annular void 372. When the gas pressure in the void 372 is above a threshold value, the upper surface of the tapered region 350 is pushed upward, and when the gas pressure is below the threshold value, the upper surface of the tapered region 350 is pushed downward.

[0058]

[0062] The gas pressure uniformly applies a force to the inner surface of the void 372. In some embodiments, an annular seal 374 connecting the outer edge of the upper platen 312 to the outer edge of the platen 310 maintains the position of the edge of the upper platen 312 when the gas pressure in the void 372 exceeds the threshold value. Thereby, a curved upper surface of the outer region 316 of the upper platen 312 is realized in which the point between the edge of the central region 314 and the outer edge of the outer region 316 is most displaced.

[0059]

[0063] In some implementations, the upper platen 312 is composed of multiple parts that operate independently to achieve the desired configuration of the polishing pad 30. FIGS. 4A and 4B show an exemplary configuration of a rotatable platen 24 in which the upper platen 412 is divided into multiple parts by virtue of a flexure portion 414, for example, having higher flexibility than the surrounding material. The flexure portion 414 can be achieved by an annular region with a reduced thickness within the material of the upper platen 312, or can be separately configured with a material that is more flexible than the remaining upper platen 412, for example, the outer region 416 or the inner portion 418. The region with the reduced thickness may be formed by a recess formed on the lower surface of the platen 24, and when no active biasing is applied, the top surface of the platen can be substantially planar.

[0060]

[0064] The lower platen 410 includes a recess 428 in which one or more actuators are disposed. The actuators apply a vertical force to the inner portion 418. In such an implementation, the vertical position of the inner portion 418 is controlled to adjust the polishing rate in the outer region 416. In the embodiment of FIG. 4A, the recess 428 houses two actuators 430 and 432 supported by a support 427. The actuators 430 and 432 apply a force in the vertical direction (e.g., parallel to the central axis 125) to the inner portion 418 to displace the inner portion 418 upward or downward relative to the edge of the outer region 416, achieving differential polishing of the region of the substrate 10 that contacts the outer region 416.

[0061]

[0065] In some implementations, the upper platen 412 is divided into more than two regions having differential polishing rates. In the exemplary implementation of FIG. 4B, three actuators 430, 432, and 434 are supported by a support 427 within the recess 428. The actuators 430, 432, and 434 control the positions of the inner portion 418 and the central portion 420. In such an implementation, the vertical positions of the inner portion 418 and the central portion 420 are independently controlled such that a difference in position occurs in one or more parts and the pressure on the substrate 10 is biased.

[0062]

[0066] FIG. 5 is a block diagram of an exemplary computer system 500. For example, controller 190 may be an example of system 500 described herein, similar to a computer system used by any user accessing the resources of system 500. System 500 includes a processor 510, a memory 520, a storage device 530, and one or more input / output interface devices 540. Each component 510, 520, 530, and 540 may be interconnected, for example, using a system bus 550.

[0063]

[0067] Processor 510 can process instructions for execution within system 500. As used herein, the term “execution” refers to the technique by which program code causes one or more processor instructions to be executed by a processor. In some implementations, processor 510 is a single-threaded processor. In some implementations, processor 510 is a multi-threaded processor. Processor 510 can process instructions stored in memory 520 or storage device 530. Processor 510 can execute operations such as controlling the polishing process described herein.

[0064]

[0068] Memory 520 stores information within system 500. In some implementations, memory 520 is a computer-readable medium. In some implementations, memory 520 is a volatile memory unit. In some implementations, memory 520 is a non-volatile memory unit.

[0065]

[0069] Storage device 530 can provide mass storage for system 500. In some implementations, storage device 530 is a non-transitory computer-readable medium. In various different implementations, storage device 530 may include, for example, a hard disk device, an optical disk device, a solid state drive, or a flash drive. In some implementations, storage device 530 may be a cloud storage device, for example, a logical storage device including one or more physical storage devices distributed over a network and accessed using the network.

[0066]

[0070] The input / output interface device 540 provides input / output operations to the system 500. In some implementations, the input / output interface device 540 may include one or more of a network interface device, such as an Ethernet interface, and / or a wireless interface device. The network interface device enables the system 500 to perform communications such as sending and receiving data via a network. In some implementations, mobile computing devices, mobile communication devices, and other devices can be used.

[0067]

[0071] The software can be realized by instructions that cause one or more processing devices to execute the above-described processes and functions at runtime. Such instructions may include, for example, interpreted instructions such as script instructions, executable code, or other instructions stored in a computer-readable medium.

[0068]

[0072] Although an exemplary processing system has been described with reference to FIG. 5, the implementations of the above-described subject matter and functional operations can be implemented in other types of digital electronic circuits, or computer software, firmware, or hardware, or a combination of one or more of them, including the structures disclosed herein and their structural equivalents. Implementations of the subject matter described herein, such as the storage, maintenance, and display of artifacts, can be implemented as one or more computer program products, i.e., as one or more modules of computer program instructions encoded on a tangible program carrier, such as a computer-readable medium, for execution by a processing system or for controlling the operation of a processing system. The computer-readable medium may be a machine-readable storage device, a machine-readable storage substrate, a memory device, or a combination of one or more of them.

[0069]

[0073] A computer program (also known as a program, software, software application, script, executable logic, or code) can be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. Computer-readable media suitable for storing computer program instructions and data include any form of non-volatile or volatile memory, media, and storage devices.

[0070]

[0074] Although many details have been set forth in this specification, these should not be construed as limiting the claims, but rather as descriptions of features specific to particular embodiments. The specific features described in the context of separate implementations herein can also be combined. Conversely, the various features described in the context of a single implementation can also be implemented separately in multiple embodiments or in any suitable sub-combination.

Claims

1. A chemical mechanical polishing apparatus, comprising: A platen for supporting a polishing pad, the platen having a central portion with an upper surface and an annular flexure portion surrounding or surrounded by the central portion, the annular flexure portion having a top surface with a first edge adjacent to and in the same plane as the upper surface and a second edge remote from the central portion; An actuator disposed to bend the annular flexure portion along the entire circumference thereof to correct a vertical position of the second edge of the annular flexure portion relative to the central portion; A carrier head for holding a surface of a substrate against the polishing pad; A motor for generating relative movement between the platen and the carrier head to polish an upper layer on the substrate. The apparatus.

2. The apparatus according to claim 1, wherein the annular flexure portion surrounds the central portion of the platen and has an inner edge adjacent to and in the same plane as the upper surface and an outer edge remote from the central portion, and the actuator is disposed to correct the vertical position of the outer edge.

3. The apparatus according to claim 2, wherein the annular flexure portion is at the outermost side of the platen and includes a width of 25% of the radius of the platen.

4. The apparatus according to claim 2, further comprising a second annular flexure portion surrounded by the central portion of the platen and having an inner edge adjacent to and in the same plane as the upper surface and an outer edge remote from the central portion, and a second actuator is disposed to correct the vertical position of the inner edge of the second annular flexure portion.

5. The apparatus according to claim 1, wherein the annular flexure portion includes an annular recess on the lower surface of the platen that extends partially through the thickness of the platen.

6. The apparatus according to claim 1, further comprising an in-situ monitoring system and a controller configured to receive a signal from the in-situ monitoring system and control the actuator based on the received signal.

7. The apparatus according to claim 1, wherein the flexure portion includes a flange extending downward, and the actuator is positioned to apply a horizontal force to the flange.

8. The apparatus according to claim 7, wherein the actuator includes a pneumatic actuator for pressing the flange or an adjusting screw inserted into a tapped recess through an opening in the flange.

9. The apparatus according to claim 1, wherein the actuator is positioned to apply a force in a vertical direction to the annular flexure portion.

10. The apparatus according to claim 9, further comprising a lower platen that supports the central portion of the platen.

11. The apparatus according to claim 10, wherein the actuator comprises an annular pressurizable chamber positioned between an upper platen and the lower platen.

12. The apparatus according to claim 1, wherein the annular flange includes a tapered edge of the platen.

13. The apparatus according to claim 1, comprising an annular support that supports the annular flexure portion, wherein the central portion is movable in a vertical direction.

14. The apparatus according to claim 13, wherein the actuator is positioned to apply a force in a vertical direction to the central portion of the platen.

15. A method of locally polishing a substrate, comprising: supporting a polishing pad with a rotatable platen, the platen including at least one annular flexure portion extending from a central region of the platen and an actuator supported by the platen configured to adjust a vertical height of an edge of the annular flexure portion relative to the central region along an entire circumference of the annular flexure portion; positioning the substrate such that a portion of the substrate is over the annular flexure portion and an annular region of the substrate moves over the annular portion; generating a relative motion between the polishing pad and the substrate to polish an upper layer on the substrate. The method includes.

16. determining a thickness profile of an upper layer; determining from the thickness profile to provide differential polishing to an annular region of the substrate; adjusting a height of an edge of the annular flexure portion relative to a central region to provide the differential polishing to the annular region of the substrate. The method according to claim 15, further comprising.

17. The method according to claim 16, further comprising continuing the relative motion between the polishing pad and the substrate until the annular region of the substrate is within a uniformity threshold of the remaining substrate.

18. The method according to claim 17, wherein the determining includes receiving a signal from an in-situ optical monitoring system indicating a radially dependent thickness of the upper layer.

19. A chemical mechanical polishing apparatus, comprising: A platen for supporting a polishing pad, the platen having a central portion with an upper surface and an annular flexure portion surrounding or surrounded by the central portion, the annular flexure portion having a top surface with a first edge adjacent to and in the same plane as the upper surface and a second edge remote from the central portion, the annular flexure portion being tapered so as to become thinner toward the second edge, the platen, An actuator arranged to bend the annular flexure portion to correct the vertical position of the second edge of the annular flexure portion relative to the central portion, A carrier head for holding the surface of a substrate against the polishing pad, A motor for generating relative movement between the platen and the carrier head to polish an upper layer on the substrate Comprising an apparatus.

20. A chemical mechanical polishing apparatus, A platen for supporting a polishing pad, having an upper part and a lower part, the upper part having a central portion with an upper surface, the platen, An annular flexure portion surrounding or surrounded by the central portion, the annular flexure portion having a top surface with a first edge adjacent to and in the same plane as the upper surface and a second edge remote from the central portion, A pressurizable chamber between the upper platen and the lower platen, the chamber being arranged to bend the annular flexure portion by changing the pressure in the chamber to correct the vertical position of the second edge of the annular flexure portion, A carrier head for holding the surface of a substrate against the polishing pad, A motor for generating relative movement between the platen and the carrier head to polish an upper layer on the substrate Comprising an apparatus.

21. A chemical mechanical polishing apparatus, A platen, A lower platen, An upper platen for supporting a polishing pad, having a vertically movable central portion and an annular outer portion surrounding the central portion and coupled to the central portion by an annular bendable portion, the outer edge of the annular outer portion being supported by the lower platen and fixed in the vertical direction with respect to the lower platen, the upper platen Including a platen, An actuator arranged to correct the inclination of the annular outer portion by adjusting the vertical positions of the central portion and the inner edge of the annular outer portion, A carrier head for holding the surface of a substrate against the polishing pad, A motor that generates relative movement between the platen and the carrier head to polish the upper layer on the substrate, and An apparatus comprising the same.

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