Control of platform shape in chemical mechanical polishing

Abstract

A chemical mechanical polishing apparatus includes: a platform for supporting a polishing pad; an actuator; the bearing head is used for fixedly abutting the surface of the substrate against the polishing pad; and the motor is used for generating relative movement between the platform and the bearing head so as to polish the covering layer on the substrate. The platform has a central portion having an upper surface and an annular flexure surrounding or surrounded by the central portion, and the annular flexure has a top surface having a first edge adjacent to and coplanar with the upper surface and a second edge remote from the central portion. The actuator is arranged to bend the annular flexure along the entire circumference of the annular flexure so as to modify the vertical position of the second edge of the annular flexure relative to the central portion.

Description

Technical Field

[0001] The present disclosure relates to chemical mechanical polishing, and more particularly to land shape control in chemical mechanical polishing. Background Art

[0002] Integrated circuits are typically formed on a substrate by sequentially depositing a conductive layer, a semiconductor layer, or an insulating layer on a silicon wafer. One manufacturing step involves depositing a fill layer onto a non-planar surface and planarizing the fill layer. For some applications, the fill layer is planarized until the top surface of the patterned layer is exposed. For example, a conductive fill layer may be deposited on a patterned insulating layer to fill grooves or holes in the insulating layer. After planarization, portions of the metal layer remaining between the protruding patterns of the insulating layer form vias, plugs, and lines that provide conductive paths between thin-film circuits on the substrate. For other applications (such as oxide polishing), the fill layer is planarized (e.g., by polishing for a predetermined period of time) to leave a portion of the fill layer on the non-planar surface. In addition, photolithography typically requires planarizing the substrate surface.

[0003] One problem in CMP is the variation in material removal rate and subsequent substrate thickness distribution. Variations in slurry distribution, polishing pad conditions, relative speed between the polishing pad and substrate, and non-uniform loading on the substrate from the pressurized chamber of the carrier head can lead to variations in material removal rate. These variations, along with variations in the initial thickness of the substrate layer, lead to variations in the final substrate layer thickness, especially in the edge region. Summary of the invention

[0004] A chemical mechanical polishing apparatus is disclosed herein, the apparatus including an annular flexure located in one or more regions of a platform supporting a polishing pad. The annular flexure is controlled to vertically offset an outer edge. A carrier head moves a portion of a substrate over the outer edge of the flexure to locally increase or decrease the polishing rate, which can reduce the presence of polishing non-uniformities in the polished substrate. A controller of the apparatus controls the displacement or position of the annular flexure through an actuator supported by the platform.

[0005] The apparatus includes an in-situ monitoring system, such as an optical monitoring system, that receives a signal indicative of a radial thickness distribution of a blanket of material on a substrate. A controller processes the signal and determines whether additional polishing is required in an annular region of the substrate, such as an annular region at an edge of the substrate. When additional polishing is required, the controller causes the actuator to flex the annular flexure upward, and when less polishing is required, the controller causes the actuator to flex the annular flexure downward. The carrier head moves a portion of the substrate over the flexure region for additional polishing.

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

[0007] In one aspect, a chemical mechanical polishing apparatus includes: a platform for supporting a polishing pad; an actuator; a carrier head for fixing a surface of a substrate against the polishing pad; and a motor for causing relative movement between the platform and the carrier head to polish a cover layer on the substrate. The platform has a central portion and an annular flexure, the central portion having an upper surface, the annular flexure surrounding or surrounded by the central portion, the annular flexure having a top surface, the top surface having a first edge adjacent to and coplanar with the upper surface and a second edge away from the central portion. The actuator is arranged to bend the annular flexure along the entire circumference of the annular flexure so as to modify the vertical position of the second edge of the annular flexure relative to the central portion.

[0008] Embodiments may include one or more of the following features. The annular flexure may be surrounded by a central portion of the platform, the annular flexure having an outer edge adjacent to and coplanar with the upper surface and an inner edge distal to the central portion, and the actuator may be arranged to modify the vertical position of the inner edge. The annular flexure may include a radius not exceeding the innermost 25% of the platform. The in-situ monitoring system may include a sensor head supported by the platform so that the sensor head passes under the carrier head and receives an optical signal from a substrate secured by the carrier head. The thickness of the flexure may be substantially equal to the thickness of the platform in the central portion. An annular seal may be positioned at the outer edge of the annular flexure.

[0009] In another aspect, a method for polishing a substrate includes: supporting a polishing pad with a rotatable platform, the platform including at least one annular flexure extending from a central region of the platform and an actuator supported by the platform, the actuator being configured to adjust a vertical height of an edge of the annular flexure relative to the central region along an entire circumference of the annular flexure; positioning the substrate so that a portion of the substrate is located above the annular flexure; moving the annular region of the substrate over the annular portion; and causing relative motion between the polishing pad and the substrate to polish a cover layer on the substrate.

[0010] In another aspect, a chemical mechanical polishing apparatus includes: a platform for supporting a polishing pad; a carrier head for fixing a surface of a substrate against the polishing pad; and a motor for causing relative movement between the platform and the carrier head to polish a cover layer on the substrate. The platform has a central portion and an annular flexure, the central portion has an upper surface, the annular flexure surrounds or is surrounded by the central portion, the annular flexure has a top surface, the top surface has a first edge adjacent to and coplanar with the upper surface, and a second edge away from the central portion. The annular flexure has a tapered shape and tapers toward the second edge. The actuator is arranged to bend the annular flexure so as to modify the vertical position of the second edge of the annular flexure relative to the central portion.

[0011] In another aspect, a chemical mechanical polishing apparatus includes: a platform for supporting a polishing pad; a carrier head for fixing a surface of a substrate against the polishing pad; and a motor for causing relative movement between the platform and the carrier head to polish a cover layer on the substrate. The platform has an upper portion and a lower portion, the upper portion having a central portion with an upper surface. An annular flexure surrounds or is surrounded by the central portion, the annular flexure having a top surface, the top surface having a first edge adjacent to and coplanar with the upper surface and a second edge distal to the central portion. A pressurized chamber between the upper and lower platforms is configured such that modifying the pressurization of the chamber causes the annular flexure to bend, thereby modifying the vertical position of the second edge of the annular flexure.

[0012] In another aspect, a chemical mechanical polishing apparatus includes: a platform having a lower platform and an upper platform for supporting a polishing pad; a carrier head for fixing a surface of a substrate against the polishing pad; and a motor for causing relative movement between the platform and the carrier head to polish a cover layer on the substrate. The upper platform has a vertically movable central portion and an annular outer portion, the 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 is supported by the lower platform and vertically fixed relative to the lower platform. The actuator is arranged to adjust the vertical position of the central portion and the inner edge of the annular outer portion to modify the inclination of the annular outer portion.

[0013] Embodiments may include one or more of the following features. The annular flexible portion may be provided by an annular recess formed into the lower surface of the upper platen. The central portion may have a taper to taper toward the annular outer portion. The annular outer portion may have a taper to taper toward the central portion.

[0014] Particular implementations of the subject matter described in this specification can be implemented to achieve one or more of the following technical advantages.

[0015] Radial specific thickness distribution correction can be performed, and intra-wafer and inter-wafer non-uniformities can be reduced. Material removal can compensate for thickness distribution non-uniformities in edge regions caused after a main polishing step, or correct incoming substrate film thickness distribution before primary polishing is performed. The amount of deflection of the annular flexure (e.g., displacement from a planar configuration) results in a modification of the pressure applied to the substrate surface rather than through the back side of the substrate, thereby increasing polishing position specificity during position specific polishing. The size of the region of increased pressure can be small compared to the entire substrate surface area and can be controlled by positioning the substrate with a carrier head, allowing material removal in highly specific regions.

[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 A schematic cross-sectional view of an example of a polishing apparatus having an optical monitoring system and two annular flexures is shown.

[0018] Figure 2A and Figure 2B A top view of a polishing pad including inner and outer regions where the polishing rate is increased is shown.

[0019] FIG. 3A to FIG. 3C A schematic cross-sectional view of an example embodiment of annular flexure actuation is shown.

[0020] Figure 4A and Figure 4B A schematic cross-sectional view of an example polishing apparatus having a lower platform and an upper platform divided into a plurality of regions to achieve a target polish is shown.

[0021] Figure 5 A schematic diagram of an example computing device is shown.

[0022] In the drawings, like reference numerals denote like elements. DETAILED DESCRIPTION

[0023] In some chemical mechanical polishing operations, a portion of the substrate may be under-polished or over-polished. Specifically, the substrate tends to be under-polished or over-polished at or near the edge of the substrate. One technique to address this polishing non-uniformity is to have multiple controllable pressurized chambers in the carrier head. However, the pressure applied from the back of the substrate tends to "spread", making radial local compensation difficult. Another technique is to transfer the substrate to a separate "touch up" tool, for example to perform edge correction. However, the additional tool takes up valuable floor space in the clean room and can adversely affect throughput.

[0024] Another method is to use a platform with independently controllable annular flexures that are deflectable, for example, upward or downward. A portion of the substrate is then moved over the deflected flexures, which causes the pressure between the polishing pad and the substrate at this portion to increase or decrease, and thus radial target polishing of the edge portion of the substrate can be achieved.

[0025] Although some approaches for adjustable stages have been proposed, such systems have not yet been commercialized and are generally expected to present other problems. For example, in systems with vertically adjustable concentric stages, the vertical displacement between the stages can create height discontinuities, creating a risk of damaging the substrate.

[0026] Figure 1 A polishing system 20 is shown that is operable to polish a substrate 10. The polishing system 20 includes a rotatable platform 24 with a primary polishing pad 30 located on the platform 24. The platform is operable to rotate about a rotation axis 25. For example, a motor 21 can rotate a drive shaft 22 to rotate the platform 24. In some embodiments, the platform 24 includes a central portion 26 that is configured to provide an annular upper surface 28 to support the primary polishing pad 30.

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

[0028] The polishing system 20 can include a polishing liquid delivery arm 39 and / or a pad cleaning system, such as a rinse fluid delivery arm. During polishing, the arm 39 is operable to dispense a polishing liquid 38, such as a slurry having abrasive particles. In some embodiments, the polishing system 20 includes a combined slurry / rinse arm. Alternatively, the polishing system can include a port in the platform that is operable to dispense the polishing liquid 38 onto the primary polishing pad 30. The polishing system 20 can also include an adjustment system 40 having a rotatable adjustment head 42 that can include, for example, an abrasive lower surface on a removable adjustment disk to adjust the polishing surface 36 of the primary polishing pad 30.

[0029] The polishing system 20 includes a carrier head 70 operable to hold the substrate 10 on the primary polishing pad 30. The carrier head 70 is suspended from a support structure 72 (e.g., a turntable or track) and is connected to a carrier head rotation motor 76 by a drive shaft 74 so that the carrier head can rotate about an axis 71. In addition, the carrier head 70 can oscillate laterally on the polishing pad, such as by moving in radial grooves in the turntable under the drive of an actuator, by rotating the turntable under the drive of a motor, or by moving back and forth along the track driven by an actuator. In operation, the platform 24 rotates about the central axis 25 of the platform 24, and the carrier head rotates about the central axis 71 of the carrier head and is laterally displaced across the top surface of the polishing pad.

[0030] The carrier head 70 may include a retaining ring 73 to hold the substrate 10 below the flexible membrane 144. The carrier head 70 also includes one or more independently controllable pressure chambers defined by the membrane, such as three chambers 77a-77c, which can apply independently controllable pressure to associated zones on the flexible membrane 144 (and therefore on the substrate 10). Although for ease of illustration, Figure 1 Only three chambers are illustrated, but there may be one or two chambers, or four or more chambers, for example five chambers.

[0031] A controller 90, such as a programmable computer, is connected to the motors 21, 76 to control the rotation rate of the platform 24 and the carrier head 70. For example, each motor may include an encoder for measuring the rotation rate of the associated drive shaft. Feedback control circuitry may be in the motor itself, part of the controller, or in a separate circuit, receiving the measured rotation rate from the encoder and adjusting the current supplied to the motor to ensure that the rotation rate of the drive shaft matches the rotation rate received from the controller.

[0032] The polishing system 20 also includes at least one annular flange 50 that is fixed to the platform 24 and rotates with the platform 24. A portion of the polishing pad 30 supported on the platform 24 extends above the flexure 50. The flexure 50 can be deformed by one or more actuators 52. The polishing system 20 may include an annular flexure 50a that protrudes outward from the outer edge of the platform 24. Alternatively, if the platform 24 itself is annular, the polishing system may include an annular flexure 50b that protrudes inward from the inner edge of the annular platform 24. Alternatively, there may be two flexures, such as flexure 50a and flexure 50b, one for the outer edge of the platform 24 and one for the inner edge of the platform 24.

[0033] When the annular flexure 50 flexes upward, the radially limited outer portion of the polishing pad 30 is pushed upward. If a portion of the substrate 10 is present above the flexure, the pressure acting on this portion will increase. Conversely, when the annular flexure 50 flexes downward, the radially limited outer portion of the polishing pad 30 is pushed downward. If a portion of the substrate 10 is present above the flexure, the pressure acting on this portion will decrease. The terms "upward" and "downward" as used herein are references to Figure 1 Upward refers to the direction from the platform 24 to the polishing pad 30 to the substrate 10, while downward refers to the opposite direction; in operation, the polishing surface can have a vertical orientation or some other orientation relative to gravity.

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

[0035] In some embodiments, the polishing apparatus includes an in-situ monitoring system 160, such as an optical monitoring system, such as a spectral monitoring system, which can be used to measure the spectrum of reflected light from a substrate undergoing polishing. The monitoring system 160 can include a sensor supported on a platform, such as one end of an optical fiber coupled to a light source 162 and a light detector 164. Due to the rotation of the platform, the monitoring system 160 receives measurements at a sampling frequency as the sensor travels under the carrier head 70 and the substrate 10, so that the measurements are taken at arc positions across the substrate 10. Based on the measurements, the in-situ monitoring system 160 generates a signal that depends on the thickness of the material layer being polished, such as a thickness distribution. Additionally or alternatively, the in-situ monitoring system 160 generates a signal that depends on the polishing rate of the material layer being polished, such as a polishing rate distribution.

[0036] The controller 90 receives the signal, converts the signal into a processing profile, such as a thickness profile or a polishing rate profile, and compares the processing profile to a target profile. For example, the target profile can be a predetermined target thickness profile of the radially related thickness of the layer at the end of polishing, or a target polishing rate profile that stores a radially related target polishing rate during polishing. The processing profile can be based on a measurement of the radial width of the substrate 10 or a portion of the radial width of the substrate 10. In some embodiments, the controller 90 calculates the processing profile of a portion of the substrate 10 corresponding to the outermost annular region of the substrate 10, such as the outermost 5%, the outermost 10%, or the outermost 20% of the substrate.

[0037] The controller 90 compares the process profile to the target profile. If the process profile differs from the target profile by more than a threshold amount, the controller 90 determines to change the polishing parameters. If the difference occurs in an area of ​​the substrate that can be controlled by the flexure, for example, in an outermost annular area adjacent to the edge of the substrate 10, the flexure can be used to compensate for the deviation of the process profile from the target profile.

[0038] If the polishing rate of the area of ​​the substrate is higher than the target polishing rate, the controller 90 can determine to position the area above the flexure and deflect the flexure downward. The downward deflection reduces the polishing rate of this area to achieve the target polishing rate distribution. If the polishing rate in this area of ​​the substrate is lower than the target polishing rate of this area, the controller 90 can determine to position this area above the flexure and deflect the flexure upward to increase the polishing rate of this area.

[0039] like Figure 1 As shown in the example of FIG. 2 , the polishing system 20 includes an annular flexure 50 that protrudes radially outward from the central portion 26 of the platform 24. If there is no deflection or deformation, the top surface of the annular flexure 50 is substantially coplanar with the upper surface 28 of the platform 24. The inner edge of the annular flexure 50 is fixed to the platform 24 and can rotate with the platform 24. Therefore, when the drive shaft 22 rotates the platform 24, the annular flexure 50 can rotate with the platform 24 (so the annular flexure 50 does not require a separate motor to rotate).

[0040] The annular flexure 50 is connected to at least one actuator 52, which is arranged to be supported by the central portion 26 of the platform 24. In some embodiments, such as Figure 1 In an example of a platform 24, the actuator 52 is arranged to provide a substantially lateral force on the flange 54. The flange 54 protrudes downward from the outer edge of the annular flexure 50. In such an embodiment, the actuator 52 provides an inward force (e.g., toward the axis of rotation 25) or an outward force (e.g., 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 circumference of the platform 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 can be spaced at uniform angles around the axis of rotation 25 of the platform 24.

[0041] When the actuator 52 provides an inward force, the outer edge of the upper surface of the annular flexure 50 is deflected downward. Conversely, when the actuator 52 provides an outward force, the outer edge of the upper surface of the annular flexure 50 is deflected upward. The controller 90 controls the actuator 52 to adjust the force on the flange 54 to control the outer edge of the upper surface of the annular flexure 50 to deflect upward or downward.

[0042] The system can be configured so that the annular flexure 50 flexes along the entire circumference of the flexure 50. In some embodiments, there is a single actuator, and the flexure 50 is sufficiently rigid along the angle so that pressure from the actuator in a limited area causes the flexure 50 to flex along the entire circumference. In some embodiments, there are multiple actuators, and the actuators are electrically ganged to a single control signal so that all actuators are driven in unison. In some embodiments, each actuator 52 can be individually controlled by the controller 90, but the controller 90 controls all actuators 52 to flex the annular flexure 50 along the entire circumference.

[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 insufficiently polished, resulting in an increase in the layer thickness at the edge of the substrate 10. Thus, the annular flexure 50 is deflected upward and biased relative to the bottom surface of the substrate 10 to increase the pressure between the substrate 10 and the polishing pad 30.

[0044] The controller 90 operates the actuator 52 to change the position of the outer edge of the annular flexure 50 up or down by a certain distance. In some embodiments, the distance is in the range of 1 micron to 300 microns (e.g., 1 micron to 250 microns, 10 microns to 250 microns, 50 microns to 250 microns, 10 microns to 50 microns, or 1 micron to 50 microns).

[0045] Here and throughout the specification, when referring to a measurable value such as an amount, duration, etc., the recitation of such a value should be considered to disclose the exact value, disclose the approximate value, and disclose the vicinity of the value, such as within ±10% of the value. For example, reference herein to 100 microns can be considered to be a reference to any of exactly 100 microns, approximately 100 microns, and within ±10% of 100 microns.

[0046] In some embodiments, the annular platform 24 includes a recess 27 located in the center of the platform 24, and the recess 27 extends partially through the thickness of the platform 24, aligned with the rotation axis 25. For example, the recess 27 can be circular and the center of the recess 27 can be coaxial with the rotation axis 25. In some embodiments, the recess 27 extends through the entire thickness of the platform 24.

[0047] The recess accommodates a central annular flexure 51 that includes a flange 54 and one or more actuators 52 to apply a force to the flange 54. An inner edge of the central annular flexure 51 (e.g., closest to the axis of rotation 25) flexes upward or downward based on the force applied to the flange 54 by the actuator 52, while an outer edge of the central annular flexure 51 remains substantially coplanar with the upper surface 28.

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

[0049] The arrangement of the actuator 52, the outer annular flexure 50a, and the center annular flexure 50b defines an area 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. Figure 2A and Figure 2B , a top view of the polishing pad 30 and substrate 10 is shown, and a specific polishing area is outlined. Figure 2A An embodiment in which the device 100 includes only the outer annular flexure 50a is depicted, while Figure 2B An embodiment of the apparatus 100 including an outer annular flexure 50a and a center annular flexure 50b is depicted. While the retaining ring 73 surrounds the substrate 10 in the apparatus 100 during the polishing operation, Figure 2A and Figure 2B In order to simplify the description, the components are visually removed.

[0050] refer to Figure 1 and Figure 2A , shows a top view of a pad 30 supported by a platform 24 and a substrate 10, wherein the system 20 includes only an outer annular flexure 50a. The central portion 26 of the platform 24 supports the central region 31 of the pad 30. The annular flexure 50a is arranged circumferentially around the platform 24 and supports the outer region 33. The outer edge of the outer region 33 flexes upward or downward while the inner edge of the outer region 33 remains substantially coplanar with the central region 31.

[0051] The substrate 10 is moved by the carrier head 70 such that a portion 12 of the substrate 10 is positioned above the outer region 33. Depending on whether the flexure 50a is biased upward or downward, the outer region 33 will experience increased or decreased pressure on the portion 12 of the substrate 10. Due to the rotation of the carrier head 70 and substrate 10 (indicated by arrow A), the annular portion 12a of the substrate 10 experiences an increased or decreased polishing rate (compared to the flexure remaining in a planar state).

[0052] refer to Figure 1 and Figure 2B, shows a top view of a pad 30 supported by a platform 24 and a substrate 10, wherein the system 20 includes an annular flexure 50 and a central annular flexure 50b. The central annular flexure 50b defines an inner region 35 of the polishing pad 30, while the outer annular flexure 50a defines an outer region 33. The polishing pad 30 supported by the central portion 26 that remains substantially flat during polishing is defined as a central region 31. In this manner, the outer region 33 and the inner region 35 define two regions in which the pressure between the substrate 10 and the polishing pad 30 can be varied.

[0053] As substrate 10 is moved across inner region 35 by carrier head 70 (not shown), portion 13 of substrate 10 overlaps inner region 35. As inner region 35 is flexed upward or downward by center annular flexure 51, portion 13 is subjected to increasing or decreasing pressure. Again, due to the rotation of carrier head 70 and substrate 10 (indicated by arrow A), annular portion 13a of substrate 10 experiences increasing or decreasing polishing rate. Figure 2A and Figure 2B In an embodiment, assuming that the substrate edge is otherwise under-polished, the polishing rate of portions 12 and 13 of substrate 10 overlapping inner region 35 and outer region 33 may be increased to compensate and thereby improve intra-wafer and inter-wafer uniformity.

[0054] The carrier head 70 passes the substrate 10 over the central region 31 and the optical monitoring system 160 receives a signal indicative of an updated thickness (eg, an updated thickness distribution) of the cover material layer and calculates a new uniformity value for the updated thickness distribution.

[0055] The controller 90 compares the updated uniformity value with the uniformity threshold. If the uniformity value is lower than the uniformity threshold, the controller 90 determines to stop the incremental polishing of the area of ​​the substrate 10 corresponding to the area exceeding the uniformity threshold.

[0056] FIG. 3A to FIG. 3C An exemplary embodiment for achieving deflection of the edge portion of the platform 324 is shown, which can provide the platform 24. FIG. 3A to FIG. 3C In an embodiment, the platform 324 includes a lower platform 310 and an upper platform 312. The upper platform 312 supports the polishing pad 30 and is supported by the lower platform 310. The material constituting the upper platform 312 has sufficient flexibility to achieve the flexure distance of the annular flexure 50, while being sufficiently durable and incompressible to be compatible with the polishing operation. In some examples, the upper platform 312 is composed of a polymer material or a metal material such as aluminum.

[0057] The upper platform 312 includes a tapered region 350 that can provide the flexure 50. For the outer annular flexure 50a, the tapered region can be the annular outer region 316 of the upper platform 312; for the inner annular flexure 50b, the tapered region can be the annular inner region of the upper platform 312. The tapered region 350 can have a reduced thickness compared to the inner central region 314. In addition, the tapered region 350 tapers to a minimum edge thickness at the outer edge of the outer region 316 (or at the inner edge of the inner region). Figure 3A The example of the embodiment of the present invention utilizes an annular flange 354 and radially spaced actuators 356 that generate a force on the flange 354 to flex the tapered region 350 of the upper platform 312. The flange 354 can be integral with the tapered region 350 of the upper platform 312, or the flange 354 can be a separate manufactured piece attached to the tapered region 350. Due to the taper, the edge of the tapered region is more flexible and therefore more susceptible to deflection. The taper reduces the force required to deform the cross section, thereby reducing the stress generated in the upper platform.

[0058] Figure 3B The example of 310 utilizes adjustment screws 362 radially spaced about the upper platform 312 to apply force to the flanges 354 in the plane of the upper platform 312 (eg, horizontally). Each adjustment screw 362 passes through a hole 329 extending through each flange 354.

[0059] In some embodiments, the upper platform 312 includes a rotary actuator 364 connected to an adjustment screw 362. The controller 90 controls the rotary actuator 364 to translate the adjustment screw 362 inwardly (e.g., toward the central axis 125), or outwardly (e.g., away from the central axis 125). Forces applied in the plane of the upper platform 312 cause the tapered region 350 to flex downwardly or upwardly based on the inward or outward translation of the adjustment screw 362, respectively. The screw can provide a mechanical advantage because rotation of the screw can generate significant force in a linear direction.

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

[0061] like Figure 3CAs shown, an annular gap 372 between the tapered region 350 and the platform 310 is sealed to prevent air flow by an annular seal 374. The platform 310 includes a passage 376 that fluidly connects the gap 372 to a gas pressurization system 378. The gas pressurization system 378 operates to change the gas pressure of the annular gap 372. Increasing the gas pressure of the gap 372 above a threshold will push the upper surface of the tapered region 350 upward, while reducing the gas pressure below the threshold will pull the upper surface of the tapered region 350 downward.

[0062] The gas pressure applies force uniformly to the inner surface of the void 372. In some examples, when the gas pressure in the void 372 increases above a threshold, an annular seal 374 connecting the outer edge of the upper platform 312 to the outer edge of the platform 310 maintains the position of the edge of the upper platform 312. This achieves a curved upper surface of the outer region 316 of the upper platform 312, wherein the point displacement between the edge of the central region 314 and the outer edge of the outer region 316 is the largest.

[0063] In some embodiments, the upper platform 312 is constructed from multiple sections that are independently actuated to achieve a desired configuration of the polishing pad 30 . Figure 4A and Figure 4B An example configuration of the rotatable platform 24 is shown, wherein the upper platform 412 is divided into several sections, such as points having a higher flexibility than the surrounding material, by flexures 414. The flexures 414 can be implemented by an annular region of reduced thickness in the upper platform 312 material, or constructed separately from a material that is more flexible than the rest of the upper platform 412 (e.g., the outer region 416 or the inner portion 418). The region of reduced thickness can be formed by a recess formed in the lower surface of the platform 24; when not actively biased, the top surface of the platen can be substantially planar.

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

[0065] In some embodiments, the upper platform 412 is divided into two or more regions with different polishing rates. Figure 4BIn an exemplary embodiment, three actuators 430, 432, and 434 are supported by a support member 427 in a recess 428. The actuators 430, 432, and 434 control the position of the inner portion 418 and the central portion 420. In such an embodiment, the vertical positions of the inner portion 418 and the central portion 420 are independently controlled so that a position difference is generated in one or more portions, thereby generating a pressure bias against the substrate 10.

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

[0067] The processor 510 is capable of processing instructions for execution within the system 500. As used herein, the term "execute" refers to the technique by which program code causes a processor to execute one or more processor instructions. In some embodiments, the processor 510 is a single-threaded processor. In some embodiments, the processor 510 is a multi-threaded processor. The processor 510 is capable of processing instructions stored in the memory 520 or on the storage device 530. The processor 510 can perform operations such as controlling the polishing operations described herein.

[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.

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

[0070] The input / output interface device 540 provides input / output operations for the system 500. In some embodiments, the input / output interface device 540 may include one or more of a network interface device (e.g., an Ethernet interface) and / or a wireless interface device. The network interface device allows the system 500 to communicate over a network, such as sending and receiving data. In some embodiments, mobile computing devices, mobile communication devices, and other devices may be used.

[0071] Software can be implemented by instructions, which, when executed, cause one or more processing devices to perform the above-mentioned processes and functions. Such instructions may include, for example, interpreted instructions, such as script instructions, or executable code, or other instructions stored in a computer-readable medium.

[0072] Although Figure 5 An example processing system has been described in the specification, but the technical subject matter and implementation of the functional operations described in this specification can be implemented in other types of digital electronic circuit systems, or in computer software, firmware or hardware, including the structures disclosed in this specification and their structural equivalents, or a combination of one or more of them. Implementations of the subject matter described in this specification, such as storage, maintenance and display artifacts, can be implemented as one or more computer program products, i.e., one or more computer program instruction modules encoded on a tangible program carrier (e.g., a computer readable medium) for execution by a processing system or controlling the operation of a processing system. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, or a combination of one or more of them.

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

[0074] Although this specification includes many details, these should not be interpreted as limitations on the scope of what may be claimed, but rather as descriptions of specific features of specific examples. Certain features described in this specification in the context of separate embodiments may also be combined. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable subcombination.

Claims

1. A chemical mechanical polishing device, comprising: a platform for supporting a polishing pad, the platform having a central portion and an annular flexure, the central portion having an upper surface, the annular flexure surrounding or surrounded by the central portion, the annular flexure having a top surface, the top surface having a first edge adjacent to and coplanar with the upper surface and a second edge distal from the central portion; an actuator arranged to bend the annular flexure along the entire circumference of the annular flexure so as to modify the vertical position of the second edge of the annular flexure relative to the central portion; a carrier head, the carrier head being used to fix the surface of the substrate against the polishing pad; as well as A motor is provided to cause relative movement between the platform and the carrier head, so as to polish the cover layer on the substrate.

2. An apparatus as claimed in claim 1, wherein the annular flexure surrounds the central portion of the platform and has an inner edge adjacent to and coplanar with the upper surface and an outer edge distal to the central portion, and the actuator is arranged to modify the vertical position of the outer edge.

3. The apparatus of claim 2, wherein the annular flexure comprises a radius that does not exceed an outermost 25% of the platform.

4. An apparatus as claimed in claim 2, comprising a second annular flexure, which is surrounded by the central portion of the platform and has an inner edge adjacent to and coplanar with the upper surface and an outer edge away from the central portion, and a second actuator is arranged to modify the vertical position of the inner edge of the second annular flexure.

5. The apparatus of claim 1, wherein the annular flexure comprises an annular recess in a lower surface of the platform, the annular recess extending partially through a thickness of the platform.

6. The apparatus of 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 of claim 1 wherein the flexure comprises a downwardly extending flange and the actuator is positioned to apply a horizontal force to the flange.

8. The device of claim 11, wherein the actuator comprises a pneumatic actuator pressed against the flange or an adjustment screw passing through a hole in the flange and into a receiving threaded recess.

9. The apparatus of claim 1, wherein the actuator is positioned to apply a perpendicular force to the annular flexure.

10. The apparatus of claim 9, further comprising a lower platform supporting the central portion of the platform.

11. The apparatus of claim 10, wherein the actuator comprises an annular pressurized chamber positioned between the upper and lower platforms.

12. The apparatus of claim 1, wherein the annular flange comprises a tapered edge of the platform.

13. The device of claim 1, comprising an annular support for supporting the annular flexure, and wherein the central portion is vertically movable.

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

15. A method for locally polishing a substrate, the method comprising: supporting a polishing pad with a rotatable platform, the platform including at least one annular flexure extending from a central region of the platform, and an actuator supported by the platform, the actuator being configured to adjust a vertical height of an edge of the annular flexure relative to the central region along an entire circumference of the annular flexure; positioning the substrate so that a portion of the substrate is located above the annular flexure; moving the annular region of the substrate over the annular portion; as well as A relative motion is generated between the polishing pad and the substrate to polish the cover layer on the substrate.

16. The method of claim 21, further comprising: determining a thickness distribution of the cover layer; providing a differential polish to an annular region of the substrate based on the thickness distribution; The height of the edge of the annular flexure relative to the central region is adjusted to provide the differential polish to an annular region of the substrate.

17. The method of claim 16, further comprising: The relative movement between the polishing pad and the substrate is continued until the annular region of the substrate is within a uniformity threshold of the remaining substrates.

18. The method of claim 17, wherein the determining comprises: A signal indicative of a radially-dependent thickness of the overburden is received from an in-situ optical monitoring system.

19. A chemical mechanical polishing device, comprising: a platform for supporting a polishing pad, the platform having a central portion and an annular flexure, the central portion having an upper surface, the annular flexure surrounding or surrounded by the central portion, the annular flexure having a top surface, the top surface having a first edge adjacent to and coplanar with the upper surface and a second edge distal from the central portion, wherein the annular flexure has a tapered shape and tapers toward the second edge; an actuator arranged to bend the annular flexure so as to modify a vertical position of the second edge of the annular flexure relative to the central portion; a carrier head, the carrier head being used to fix the surface of the substrate against the polishing pad; as well as A motor is provided to cause relative movement between the platform and the carrier head, so as to polish the cover layer on the substrate.

20. A chemical mechanical polishing device, comprising: a platform for supporting a polishing pad, the platform having an upper portion and a lower portion, the upper portion having a central portion with an upper surface; an annular flexure surrounding or surrounded by the central portion and having a top surface having a first edge adjacent to and coplanar with the upper surface and a second edge distal from the central portion; a pressurized chamber between the upper and lower platforms such that modifying the pressurization of the chamber causes the annular flexure to bend, thereby modifying the vertical position of the second edge of the annular flexure; a carrier head, the carrier head being used to fix the surface of the substrate against the polishing pad; as well as A motor is provided to cause relative movement between the platform and the carrier head, so as to polish the cover layer on the substrate.

21. A chemical mechanical polishing device, comprising: A platform comprising Lower platform, and an upper platform for supporting a polishing pad, the upper platform having a central portion capable of vertical movement and an annular outer portion, the annular outer portion surrounding the central portion and coupled to the central portion through an annular bendable portion, wherein an outer edge of the annular outer portion is supported by the lower platform and vertically fixed relative to the lower platform; an actuator arranged to adjust the vertical position of the central portion and the inner edge of the annular outer portion so as to modify the inclination of the annular outer portion; a carrier head, the carrier head being used to fix the surface of the substrate against the polishing pad; as well as A motor is provided to cause relative movement between the platform and the carrier head, so as to polish the cover layer on the substrate.

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