Polishing carrier head with variable edge control - Patents.com

Abstract

A carrier head for holding a substrate in a polishing system includes a housing, an annular body vertically movable relative to the housing by an actuator, a first annular membrane fixed to extend below the annular body and forming at least one pressurizable lower chamber between the first annular membrane and the annular body, and at least one pressure supply line connected to the at least one pressurizable lower chamber, The annular body includes an upper portion and at least one lower post projecting downwardly from the upper portion, the at least one lower post being located within the at least one pressurizable lower chamber.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to chemical mechanical polishing, and more particularly to controlling the polishing rate near the edge of a substrate. [Background technology]

[0002] Integrated circuits are typically formed on a substrate (eg, a semiconductor wafer) by successively depositing conductive, semiconductive, or insulating layers on the silicon wafer and successively processing these layers.

[0003] One manufacturing step involves depositing a fill layer over a non-planar surface and planarizing the fill layer. For certain applications, the fill layer is planarized until the top surface of the patterned layer is exposed or until a desired thickness remains above the underlying layer. In addition, planarization can be used to planarize the surface of a substrate, such as a dielectric layer, for lithography.

[0004] Chemical mechanical polishing (CMP) is one accepted method of planarization. This method of planarization typically involves mounting a substrate on a carrier head. The exposed surface of the substrate is positioned to bear against a rotating polishing pad. The carrier head provides a controllable load on the substrate to press the substrate against the polishing pad. In some polishing machines, the carrier head includes a membrane that forms a plurality of separately pressurizable radial concentric chambers, where the pressure in each chamber controls the polishing rate in each corresponding area on the substrate. A polishing fluid, such as a slurry containing abrasive particles, is supplied to the surface of the polishing pad. Summary of the Invention

[0005] In one aspect, a carrier head for holding a substrate in a polishing system includes a housing, an annular body vertically movable relative to the housing by an actuator, a first annular film fixed to extend below the annular body and forming at least one pressurizable lower chamber between the first annular film and the annular body, and at least one pressure supply line connected to the at least one pressurizable lower chamber. The annular body includes a top and at least one lower post projecting downwardly from the top, the at least one lower post being located within the at least one pressurizable lower chamber.

[0006] Particular embodiments include, but are not limited to, one or more of the following anticipated advantages.

[0007] The described techniques can improve the overall uniformity of the substrate during polishing. The system can adjust the load distribution at the edge of the substrate by applying different distributed pressures over different areas and applying one or more focused forces at different locations of the edge area of ​​the substrate. The system can adjust one or more pressures in one or more pressurizable chambers formed by the first annular membrane to change the load area and the amount of pressure distributed across the substrate.

[0008] The system may also include an annular body having one or more downwardly projecting lower posts. The system may use a variable pressure supply to deform the second annular membrane to displace the one or more lower posts substantially downwardly to contact one or more corresponding concentrated areas of the substrate and apply one or more respective concentrated forces. The location of the concentrated areas to which the respective concentrated forces are applied may be adjusted by varying the shape, location, and number of the lower posts attached to the annular body.

[0009] Thus, the system can easily accommodate a variety of edge polishing profiles and can adjust the combination of forces applied to the annular edge region of the substrate to customize the polishing rate in that region. In some embodiments, the system can adjust the polishing rate of a particular region of the substrate by increasing the effective pressure over at least one portion of the region and decreasing the effective pressure over other portions of the region. Thus, the polishing process of the annular edge region of a layer on a substrate can be dynamically controlled with greater precision.

[0010] More specifically, the effective pressure and effective area size of the edge region are determined based on the combination of loads (i.e., distributed and concentrated forces) from each chamber, providing greater flexibility to apply a specific pressure distribution to the outer portion of the wafer.

[0011] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description and drawings, and from the claims. [Brief description of the drawings]

[0012] [Figure 1] 1 shows a schematic cross-sectional view of an example of a polishing apparatus. [Diagram 2] 1 shows a schematic cross-sectional view of a carrier head. [Diagram 3] 2 is a schematic cross-sectional view of a pressure control assembly for controlling pressure against an edge region of a substrate. [Figure 4A-C] 1 illustrates another example of a pressure control assembly. [Figure 5A-C] 1 illustrates diagrammatically how a pressure control assembly applies an effective force to an area of ​​a substrate. [Figure 6A-C] 4A-4D show schematic cross-sectional views of the pressure control assembly of FIG. 3 in various states. [Figure 7A-F] 4B shows schematic cross-sectional views of the pressure control assembly of FIG. 4A in various states. [Figure 8A-C]4C show schematic cross-sectional views of the pressure control assembly of FIG. 4B in various states. [Fig. 8D-F] 4C show schematic cross-sectional views of the pressure control assembly of FIG. 4B in various states. [Figure 9A-C] 4D show schematic cross-sectional views of the pressure control assembly of FIG. 4C in various states. [Figure 10] FIG. 1 is a flow diagram illustrating an exemplary edge profile control process using a pressure control assembly during polishing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Like reference numbers and designations in the various drawings indicate like elements.

[0014] In an idealized process, the rotation of the carrier head and platen would result in a uniform polishing rate on the substrate in a radial direction from the axis of rotation of the substrate. However, in reality, radial variations in polishing rate can occur during the polishing process. Moreover, the substrate being polished may have an initial radial non-uniformity, i.e., the top layer may vary in initial thickness along a radial direction from the axis of rotation of the substrate.

[0015] Variations in polishing rate among different regions of the substrate, or a non-uniform initial profile of the substrate, or both, may cause different regions of the substrate to reach their target thickness at different times.

[0016] More specifically, various regions of the substrate may not reach the desired thickness if polishing of those regions is stopped at the same time, resulting in a non-uniform thickness profile of the substrate. In particular, an annular region having a width of about 10 mm and beginning about 4-6 mm from the edge of the substrate (also referred to as the "checkmark region") may suffer from substantial non-uniformity. In particular, the checkmark region is polished slower or is underpolished compared to the central region of the substrate after the polishing process.

[0017] One approach to modifying the polishing rate in the checkmark region is to change the pressure in the outermost chamber of the carrier head, which changes the pressure at the edge region of the substrate, e.g., the outer 15-20 mm of the substrate. However, increasing the pressure in the outermost chamber can result in severe over-polishing of the outer 1-2 mm of the substrate.

[0018] However, a carrier head employing the techniques described herein can provide better control over pressure distribution and reduce non-uniformity near the substrate edge. The carrier head can include a pressure control assembly including a first annular membrane forming one or more pressurizable chambers and an annular body having one or more lower posts extruded downward. Optionally, the annular body can include a second annular membrane to form another pressurizable annular chamber. In practice, the system can adjust the pressure in each chamber formed by the annular membrane by a controller to control both the size of the contact area between the assembly and the substrate and the pressure on the contact area. The chambers can also deform due to different pressures in the other annular chambers. In particular, the other chambers can deform to displace one or more lower posts downward to contact and apply a force to a focal area of ​​the substrate. The assembly can apply a distributed force within a controllable contact area on the substrate, or a concentrated force at a controllable concentrated area on the substrate, or both, correspondingly.

[0019] Therefore, the system can apply various combinations of distributed and concentrated forces at the edge region of the substrate in a precise and controllable manner, which allows the system to effectively control the polishing of the edge region of the substrate and reduce non-uniformity at the edge region of the substrate.

[0020] 1 shows an example of a polishing apparatus 100. The polishing apparatus 100 includes a rotatable, disk-shaped platen 120 on which a polishing pad 110 is positioned. The platen 120 is operable to rotate about an axis 125. For example, a motor 121 can turn a drive shaft 124 to rotate the platen 120. The polishing pad 110 can be removably secured to the platen 120, for example, by an adhesive layer. The polishing pad 110 can be a two-layer polishing pad including an outer polishing layer 112 and a softer backing layer 114.

[0021] The polishing apparatus 100 may include a dispense port 130 for supplying a polishing fluid 132 (such as a polishing slurry) onto the polishing pad 110. The polishing apparatus may also include a polishing pad conditioner for polishing the polishing pad 110 to maintain the polishing pad 110 in a consistent polishing condition.

[0022] The polishing apparatus 100 includes a carrier head 140 operable to hold the substrate 10 against the polishing pad 110. The carrier head 140 can be configured to independently control polishing parameters, such as pressure, for each of a number of zones on the substrate 10.

[0023] Carrier head 140 is suspended from a support structure 150, such as a carousel, and connected by a drive shaft 152 to a carrier head rotation motor 154, which allows the carrier head to rotate about axis 155. Optionally, carrier head 140 may oscillate laterally, such as on a slider on carousel 150, or may be oscillated by the rotational oscillation of the carousel itself. In operation, the platen is rotated about its central axis 125, and each carrier head is rotated about its central axis 155 and moves laterally across the top surface of the polishing pad.

[0024] The carrier head 140 may include a housing 144 connectable to the drive shaft 152, a support plate 184 extending above the flexible central membrane 182, an annular pressure control assembly 195 surrounding the flexible central membrane 182, and a retaining ring 142 surrounding the annular pressure control assembly 195 and holding the substrate 10 below the flexible central membrane 182.

[0025] The underside of the flexible central membrane 182 provides a mounting surface for the substrate 10. The flexible central membrane 182 can include one or more flaps secured to a support plate 184 to form one or more pressurizable chambers. The chambers are connected to one or more pressure supplies 181 via respective pressure supply lines 183 to apply different pressures to inner regions of the substrate (e.g., at least 6 mm away from the edge of the substrate) during polishing, thereby enabling the system to adjust the respective polishing rates at different regions within the substrate.

[0026] The pressure control assembly 195 can also define one or more pressurizable chambers, each connected to a different pressure supply 181 via a respective pressure supply line 183. A detailed structural description of the pressure control assembly 195 is provided below.

[0027] The polishing apparatus may further include a valve assembly 189, e.g., an apparatus for controllably connecting the various chambers to the various pressure supplies. For example, the valve assembly may be mounted on the housing 144 of the carrier head 140, as shown in FIG. 1. For another example, the valve assembly may be mounted on the support plate 184 within the carrier head 140. Alternatively, as described above, each chamber may also be directly connected to the pressure supply 181 via pressure supply lines 183.

[0028] The polishing apparatus may include a controller 190 that controls the pressure in each chamber formed in a pressure control assembly 195. For example, if a pressure valve assembly 189 is used, each chamber of the pressure control assembly may be connected to a dedicated valve in the valve assembly 189 via a respective pressure output line 187. Each pressure output line 187 may be provided by a passageway through the housing 144, or by flexible tubing, or both. Although only one pressure output line 187 is shown in FIG. 1 for ease of illustration, there will be a separate pressure output line 187 for each chamber in the pressure control assembly 195.

[0029] The valve assembly 189 can receive multiple pressure inputs from multiple pressure sources 181 via multiple pressure supply lines 183. Again, in FIG. 1, only one pressure supply line 183 and one pressure source 181 are shown for ease of illustration, but there can be more pressure supply lines, e.g., 8-16 pressure supply lines, and there can be more pressure sources, e.g., 8-16 pressure sources. The pressure supply lines 183 can be provided by passages and / or flexible tubing through the drive shaft 152 and / or housing 144, and a rotary union 214 extending through the housing 144. Pressure can be delivered to the carrier head 140 from a stationary component, e.g., the pressure source 183, via the rotary pneumatic union 156.

[0030] 2 shows a schematic cross-sectional view of the carrier head 140. The carrier head 140 includes a support plate 184 and a central membrane 182 having a plurality of annular or angled flaps 204. The flaps may be secured to the support plate 184 by clamps. The central membrane 182 may be made of a flexible, slightly elastic material, for example a rubber such as silicone rubber or neoprene. The membrane may be formed from a thermosetting material using a mold, such that the molded membrane is formed as a unitary body.

[0031] In some embodiments, the support plate 184 may be coupled to the housing 144 by a flexure 210, such as an annular membrane, formed of plastic or rubber, such as silicone rubber or neoprene. An inner edge of the flexure 210 may be clamped between the top of the support plate 184 and a clamp ring 212, and an outer edge of the flexure may be clamped between the retaining ring 142 and the housing 144.

[0032] The area between the support plate 184 and the housing 144 can be sealed by an expandable seal 220, for example by a flexible membrane or bellows, to form a pressurizable upper chamber 222 between the housing 144 and the support plate 184.

[0033] Alternatively, the flexures 210 could provide the seal. The pressure in the upper chamber 222 can thus control the vertical position of the support plate 184 or the downward force of the support plate 184 against the central membrane 182. In some embodiments, the pressure in the upper chamber 222 can control the pressure of the retaining ring 142 against the polishing pad. In some embodiments, the central membrane 182 is clamped directly to the housing 144, i.e., a separate support plate 184 is omitted and that function is provided by the housing 144.

[0034] Carrier head 140 further includes an annular pressure control assembly 195 disposed between retaining ring 142 and central membrane 182. Assembly 195 includes an actuator 256 located below housing 144, such as below flexures 210. In some embodiments, a top of actuator 256 can be restrained by a bottom surface of flexures 210 such that the top of actuator 256 cannot move vertically.

[0035] The actuators 256 can have a pressurizable bladder 285 connected to respective pressure output lines 187 or directly to a pressure supply chain 183 (not shown). A valve assembly 189 or pressure supply 181 can provide or vary the pressure for the pressurizable bladder 285. The bladder 285 is made of a deformable material such as plastic or rubber, such as silicone rubber or neoprene, such that the bladder 285 can deform due to changes in pressure within the bladder. Alternatively, the actuators 256 could be provided by a motor, for example a linear actuator, or a piezoelectric device.

[0036] The pressure control assembly 195 also includes an annular body 254 that is vertically movable relative to the housing 144 by an actuator 256. The annular body 254 includes an upper portion 254a and at least one lower post 290 that projects downwardly from the upper portion 254a. The annular body is made of a hard plastic, such as polyetheretherketone (PEEK) or polyphenylene sulfide (PPS), having a Young's modulus on the order of 400-500 ksi, or a metal, such as aluminum or stainless steel. The upper portion 254a of the annular body is connected to the actuator 256. For example, an upper annular post 261 of the annular body 254 can extend into a recess formed by a bottom surface of the pressurizable bladder 285.

[0037] To move the annular body 254, the control unit 190 can increase the pressure in the bladder 256 to expand the bladder, thus exerting a substantial downward pressure on the upper annular post 261 to displace the annular body 254 downwardly relative to the housing 144.

[0038] The pressure control assembly 195 further includes a first annular membrane 252 secured to the top of the annular body 254, forming at least one pressurizable lower chamber (e.g., 281 and / or 283) between the first annular membrane 252 and the annular body 254, where at least one lower post 290 is located inside the at least one pressurizable lower chamber. The first annular membrane 252 can be secured to the top 254a of the annular body 254 by a clamp, an adhesive material, or by overmolding an elastomer on the membrane. The first annular membrane 252 can be made of any suitable elastic or plastic material with a Young's modulus on the order of 100 psi, for example, rubber such as silicone rubber or neoprene.

[0039] During operation, the various chambers 222, 285, etc. may be pressurized such that the bottom surface of the first annular membrane 252 is substantially flush with the bottom surface of the central membrane 182. The central membrane 182 and the annular membrane 252 cooperate to cover substantially the entire top surface of the substrate 10 during polishing. The membranes 182, 252 may also adjust the pressure applied in respective regions of the substrate to modify the local polishing rate. In some embodiments, a gap may exist between the central membrane 182 and the annular membrane 252 when the substrate is not being polished, which gap is filled by the appropriate pressure in the chambers formed by the membranes 182 and 252 when the substrate is being polished.

[0040] Each of the one or more possible chambers 281, 283 formed by the first annular membrane 252 can be connected to a valve assembly 189 via a respective pressure output line 187 or can be directly connected to a respective pressure supply via a respective pressure supply line 183 (not shown).

[0041] The bladder 285 and each chamber 281, 283 are connected to respective pressure supplies so that the area of ​​the substrate to which pressure is applied by the assembly 195 can be controlled according to the overall combination of pressures to the chambers. For example, the contact area of ​​the first annular membrane 252 with the substrate and / or whether at least one lower post 290 in each chamber contacts and applies a force to the top surface of the membrane depends on the pressure conditions in the bladder and each chamber. The pressure conditions can be, for example, the ratio of pressures between the bladder and the chambers formed by the first annular membrane or the ratio of pressures in each chamber formed by the first annular membrane. Details of the various configurations due to the various pressure conditions are discussed further below.

[0042] The pressurizable chambers defined by the first annular membrane may include two, three or more chambers, with alternative constructions being described in more detail below.

[0043] Additionally, the number of lower posts can be three, five, or more, and the shape of the lower posts can be rectangular, cylindrical, or other suitable shape that allows for application of force in a substantially concentrated area. One or more of the lower posts can further include a flange portion that is substantially horizontally oriented, e.g., the axial direction of the flange portion is horizontal. Further details of alternative configurations of the lower posts are provided below.

[0044] FIG. 3 is a schematic cross-sectional view of a pressure control assembly 195 for controlling pressure against an edge region of a substrate.

[0045] The pressure control assembly 195 includes an annular body 254 configured to be positioned over an edge region of the substrate 10. The annular body 254 may include one or more lower posts 290a, 290b, 290c and an upper post 261.

[0046] The pressure control assembly 195 also includes an actuator 256 secured above the annulus 254. The actuator 256 includes a membrane or shell 310 that forms a pressurizable bladder 285. A passage or pipe 325 through a portion of the membrane 310 is configured to connect to an external pressure supply / output line 187b. A particular pressure can be provided to the pressurizable bladder 285 via the pressure supply line 187b and the passage 325. To connect with the annulus 254, the actuator 256 can include a recess 361 in a bottom surface of the membrane 310. The recess 361 is configured to engage and be secured to the annulus' upper post 261, for example, by a press fit or adhesive, to name just a few.

[0047] The pressure control assembly 195 further includes a first annular membrane 252 secured to an upper portion 254a of the annular body 254 and forming with a lower portion of the annular body one or more pressurizable chambers 281, 283. The first annular membrane 252 may be secured to the annular body 254 via any suitable connection, such as, for example, a clamp ring 305 or an adhesive. Each of the chambers 281, 283 formed by the first annular membrane 252 may surround one or more lower posts 290a, 290b, and 290c extending downwardly from the annular body 254.

[0048] During an initial state, e.g., before a polishing operation, the lower posts are not in contact with the inner surface of the membrane 252. However, at least one of the lower posts is configured to be displaced to contact and apply a force to a concentrated area of ​​a corresponding portion of the inner surface of the membrane 252, thereby transmitting a concentrated force in a narrow annular zone on the backside of the substrate during polishing. At least one of the lower posts 290 can be displaced, for example, by one or more pressure changes in one or more of the chambers 281, 283, or by a pressure change in the bladder 285, or both.

[0049] Each chamber 281 and 283 includes a passageway or tube, or both, for connection to a corresponding pressure supply / output line 187 for applying a respective pressure in each chamber. The passageway may be disposed through any suitable portion of the membrane 252 or the annulus 254. For example, the passageway 315 is formed starting from the top surface of the annulus 254 and extending substantially downward to the bottom surface of the lower post 290a. As another example, the passageway 320 is formed starting from the side of the annulus 254 and extending horizontally for a first portion and substantially downward for a second portion to the bottom surface of the annulus 254. Optionally, each passageway may include a pipe or tube for connection to a respective pressure supply line.

[0050] For situations in which the polishing apparatus 100 includes a valve assembly 189, each pressure supply line 187a, 187b, and 187c is connected to a respective valve in the valve assembly 189 to apply a particular pressure to each of the chambers 281, 283, and 285. The controller 190 can control the pressure changes in each chamber through the valve assembly 190, with the final configuration of the assembly 195 being changed correspondingly.

[0051] The materials, shapes, and configurations described above for each component of assembly 195 are purely exemplary for ease of explanation, and other suitable materials, designs, and configurations may be employed.

[0052] 4A-4C each show another embodiment of the pressure control assembly 195. In some embodiments, referring to the configuration presented in FIG. 4A, the annular body 254 of the pressure control assembly 195 can include a second annular membrane 254b secured to the annular body 254 and defining an upper annular chamber 450. At least one lower post 290 is secured to a bottom surface of the second annular membrane. The second annular membrane 254b is configured to deform downward in response to an increase in pressure in the upper annular chamber 450 to displace at least one lower post, e.g., 290b, downward to contact and apply a force to an upper surface of the first annular membrane 252.

[0053] In some embodiments, the first annular membrane 252 is secured to the annular body 254 to define a single lower chamber 481. Each of the chambers 285, 450, and 481 are separately pressurizable and connected to a pressure supply line via a respective passage or tube. For example, the upper annular chamber 450 can be connected to a pressure supply line using a pipe 413 in a passage through one side of the annular body 254. As another example, the chamber 481 is connected to a pressure supply line via a passage 415 located on the other side of the annular body 254.

[0054] Additionally, one of the lower posts, e.g., the radially outermost post 290a, includes a flange 291a that extends radially outward (radially outward from the center of the carrier head) into the chamber 481. The flange 291a may have any suitable annular profile. For example, the bottom surface of the flange 291a may be planar and horizontal, or planar but inclined relative to the horizontal, or non-planar. When the post 290a with the flange 291a contacts a substrate and applies a concentrated force, the applied force should be less than the force of a post without a flange.

[0055] In some embodiments, referring to the configuration presented in Figure 4B, the first annular membrane 252 can form two chambers 483 and 485, as similarly described for Figure 3. The first chamber 483 includes one lower post 290a with an inwardly extending flange 291a, and the second chamber 485 includes two lower posts 290b, 290c without flanges. Each chamber 285, 450, 483, and 485 is connected to a different pressure supply line via a respective passage or pipe.

[0056] Each lower post may have a length, width, and depth. Alternatively, each lower post may have a substantially identical shape. The bottom surfaces of one or more lower posts may be configured to be initially coplanar. Alternatively, the bottom surfaces of the lower posts may be located at various horizontal positions. In particular, in an embodiment that does not include an upper annular chamber 450, two of the posts may have coplanar bottom surfaces, such that pressure is applied by the two posts in two separate annular regions. On the other hand, in an embodiment that includes an upper annular chamber 450, the post attached to the second annular membrane, such as the central post 290b, may have a slightly shorter or slightly concave bottom surface when the upper annular chamber 250 is not pressurized.

[0057] 4C, the first annular membrane 252 can define three chambers 487, 488, and 489, where each chamber has a respective lower post. Similarly, each chamber 285, 487, 488, and 489 is connected to a different pressure supply line.

[0058] 5A-5C show a schematic of how the pressure control assembly 195 applies an effective force to an area of ​​the substrate. As a preliminary matter, the assembly 195 applies different types and magnitudes of forces in different areas of the substrate 515, taking a similar approach as the system 500, i.e., by adjusting the magnitude of the applied force. According to Newton's law, the forces shown in the following figures are reaction forces, each of the same magnitude but opposite to the corresponding force applied to the substrate. For simplicity, this reaction force will also be referred to as the force applied to the substrate.

[0059] 5A, a schematic system 500 includes a spherical or annular bladder 520 having a contained pressure P formed by a spherical or annular membrane 520, a clamp-shaped part 510 disposed on the bladder, and a substrate 515 on which the bladder 520 is initially disposed. The clamp-shaped part 510 includes a horizontal portion 510a and a vertical portion 510b. The horizontal portion of the part 510 contacts the top of the bladder such that an initial contact area 501 between the part 510 and the bladder 520 can be a concentrated area that is substantially a point or a circle depending on whether the clamp-shaped part 519 is circular or not. The vertical portion 510b of the part 510 is not initially in contact with the substrate 515 or the bladder 520, but is configured to be displaced downwards under a force applied to the horizontal portion of the part 510. The bladder 520 is also deformable by both inertial pressure P and external forces.

[0060] Initially, a downward force F, i.e. a force substantially aligned with gravity, is applied to the horizontal portion 510a of the part 510. In the area of ​​the contact area 501 between the bladder 520 and the substrate 515, the force F exerts a certain pressure 525 on the substrate. The magnitude of the pressure 525 depends on the magnitude of the downward force and the area of ​​the contact area 501 between the bladder 520 and the substrate 515. In the following description, the pressure 525 or the like is referred to as a distributed force or load.

[0061] 5B, as the magnitude of the downward force F increases, the bladder 520 deforms in cross-sectional profile to an elliptical shape, displacing the part 510 and its vertical portion 510b downwardly closer to the substrate 515. The pressure 545 or distributed force applied to the substrate through the bladder may increase as the downward force F increases. Alternatively or additionally, the contact area 501 between the bladder 520 and the substrate 515 may increase. The amount of change in the contact area between the bladder and the substrate depends at least in part on the mechanical properties of the material from which the bladder is made, the magnitude of the internal pressure P, and the magnitude of the downward force F.

[0062] 5C, the downward force F further increases in magnitude, causing the bladder 520 to further deform and the vertical portion 510b of the part 510 to further displace downwards until it contacts and directly applies a force to the substrate 515 in the second contact area 502. If the bottom surface 511 of the vertical portion 510b has a narrow profile, e.g., less than 5 mm wide, e.g., less than 3 mm wide, e.g., less than 2 mm wide, then the applied force may be considered a concentrated force, or concentrated force, or more generally, a concentrated pressure 570.

[0063] In some embodiments, it is possible to change the contact area between the bladder and the substrate by varying the different internal pressures P of the chamber while maintaining the same external load F. Thus, the system 500 can have more different types and magnitudes of forces applied to different areas of the substrate using different combinations of downward force F and internal pressure P, an idea that is adopted in the techniques described below as well.

[0064] Various states of each of the exemplary configurations of assembly 195 shown in Figures 3 and 4A-4C are described below in conjunction with Figures 6A-6C, 7A-7F, 8A-8F, and 9A-9C. Further details regarding each state in relation to controlling polishing of various edge regions are provided below.

[0065] 6A-6C show schematic cross-sectional views of the pressure control assembly 195 of FIG. 3 in various states.

[0066] 3, the first example pressure control assembly 195 includes three chambers, namely a bladder formed by actuator 256 and two chambers 281 and 283 formed by first annular membrane 252, each connected to a respective pressure supply P1, P2, and P3. The pressures P1, P2, and P3 can be varied by a variable pressure supply tank or by switching between the various pressure supplies via valve assembly 189 under control of controller 190. Pressure P1 should be in equilibrium with the other pressures P2 and P3.

[0067] 6A, the assembly 195 is in a first state, in which none of the lower posts are displaced and are not in contact with the first membrane. Thus, in the first state, the assembly 195 applies only distributed pressures 610 and 620 to the substrate 10, where the magnitudes of the pressures 610 and 620 are equal to the pressures P3 and P2 in the corresponding chambers. The first state is also referred to as a wide contact patch.

[0068] Referring to FIG. 6B, the assembly 195 is now in the second state. To change from the first state to the second state, the assembly 195 increases the pressures P2 and P3 such that the contact area between the first annular film and the substrate is reduced at equilibrium. At equilibrium, the increased pressures P2 and P3 multiplied by the corresponding reduced contact area equals P1 multiplied by the contact area of ​​the upper post. In some implementations, the assembly 195 can increase P1, P2, and P3 together to reach the second state as long as the ratio of (P2+P3) to P1 increases. In the second state, the assembly 195 can apply increased amounts of pressure 630 and 640 to a smaller area in the substrate, increasing the polishing rate in the smaller area. The magnitude of the pressures 630 and 640 is based on P3 and P2 in each chamber, respectively. The second state is also referred to as narrow contact patch.

[0069] Referring to FIG. 6C, the assembly 195 is now in a third state. To change from the first state to the second state, the assembly 195 increases the pressure P1 to displace one or more lower posts downward to contact and apply a force to the first membrane. Because the contact area between the lower posts and the first membrane is small, the assembly 195 can eventually apply a relatively concentrated force to the substrate. For example, the central post of the annulus contacts the first membrane and then applies a concentrated force 660 to the substrate. The assembly can alternately increase the pressures P1, P2, and P3 together as long as the ratio of (P2+P3) to P1 decreases and P1 is large enough compared to P2 and P3 to displace one of the posts into contact with the first membrane. The other forces applied to the substrate are distributed forces 650 and 670, which depend on the internal pressures P3 and P2 in each chamber, respectively. In the third state, the assembly 195 can apply both distributed loads and concentrated forces to the edge region. More specifically, the assembly 195 can control (e.g., increase) the polishing rate of a central region of the substrate edge in a concentrated manner by concentrated force 660. The third condition is also referred to as center-focused large area contact patch.

[0070] 7A-7F show schematic cross-sectional views of the pressure control assembly 195 of FIG. 4A in various states.

[0071] 4A, the second exemplary pressure control assembly 195 includes three chambers: a bladder formed by actuator 256, a single chamber 481 formed by a first membrane, and a chamber 450 formed by a second annular membrane (e.g., annular body 254). Each chamber is connected to a respective pressure supply P1, P2, P5, and pressures P1, P2, and P5 are variable relative to one another to allow assembly 195 to reach various states.

[0072] 7A, the assembly 195 is in a first state in which none of the lower posts are displaced and are not in contact with the first membrane. Thus, in the first state, the assembly 195 applies only a distributed pressure 710 to the substrate 10, where the magnitude of the pressure 710 is equal to the pressure P2 in the chamber 481. The first state is also referred to as a global contact patch.

[0073] Referring to FIG. 7B, the assembly 195 is in a second state. In the second state, none of the lower posts contact the first film, but the assembly applies a uniform distributed load 715 to a smaller area of ​​the substrate 10 (compared to the first state). To change from the first state to the second state, the assembly 195 can reduce the ratio of P1 to P2 and keep P5 smaller than P2. The second state is also called a narrow contact patch for controlling the polishing rate of a smaller edge area during polishing.

[0074] 7C, the assembly 195 is in a third state. In the third state, the outermost lower post 290a is displaced downwards, eventually contacting the first membrane and exerting a concentrated force 720. Thus, the assembly 195 exerts both a uniform distributed load 725 and a concentrated force 720 on the substrate 10. To change from the first state to the third state, the assembly 195 increases the ratio of pressure P1 to pressure P2 and keeps pressure P5 less than pressure P2. The third state is also referred to as outer weighted point + wide area contact patch to apply higher pressure to the outer etched regions while still exerting pressure over a wide area.

[0075] 7D, the assembly 195 is in a fourth state. In the fourth state, the central lower post 290b displaces downwards and eventually contacts the first membrane and applies a concentrated force 730. Thus, the assembly 195 applies both a uniform distributed load 735 and a concentrated force 730 to the substrate 10. To change from the first state to the fourth state, the assembly 195 increases the ratio of pressure P5 to pressure P2. The fourth state is also referred to as a central focus + wide area contact patch to apply more pressure to the central region while still applying pressure over a wide area.

[0076] Referring to FIG. 7E, the assembly 195 is in a fifth state. In the fifth state, both the outermost lower post 290a and the central lower post 290b are displaced downwards, eventually contacting the first membrane and applying concentrated forces 740, 745. Thus, the assembly 195 applies a uniform distributed load 750 in the edge region, a concentrated force 740 in the outer edge region, and another concentrated force 745 in the central edge region of the substrate 10. To change to this state from the first state, the assembly 195 increases the ratio of pressure P1 to pressure P2, or P5, or P2+P5, and increases the ratio of P5 to pressure P2. The fifth state is also referred to as outer and central focused wide area contact patch to apply more concentrated pressure to both the outer and central edge regions.

[0077] Referring to FIG. 7F, the assembly 195 is in a sixth state. Only the central lower post 290b is displaced downwards, contacting the first membrane and exerting a concentrated force 755. Thus, the assembly 195 exerts a uniform distributed load 760 in the edge region and a concentrated force 755 in the central edge region of the substrate 10. To change to this state, the assembly 195 reduces the ratio of pressure P1 to both pressures P2 and P5, and increases the ratio of pressure P5 to pressure P2. The sixth state is also referred to as central weighted + narrow contact patch, which exerts a higher pressure on the central edge region but has a narrower overall control area (compared to FIG. 7D).

[0078] 8A-8F show schematic cross-sectional views of the pressure control assembly 195 of FIG. 4B in various states.

[0079] 4B, the third exemplary pressure control assembly 195 includes four chambers: a bladder formed by actuator 256, chambers 483 and 485 formed by a first membrane, and chamber 450 formed by second annular membrane 254b (e.g., annular body 254). Each chamber is connected to a respective pressure supply P1, P2, P3, and P5, and pressures P1, P2, P3, and P5 are variable relative to one another to allow assembly 195 to reach various states.

[0080] 8A, the assembly 195 is in a first state, in which none of the lower posts are displaced and in contact with the first membrane. Thus, in the first state, the assembly 195 applies only distributed pressures 805 and 810 in the outer and inner edge regions of the substrate 10. The magnitude of each pressure 805 and 810 is equal to the corresponding pressures P3 and P2. The first state is also referred to as a global contact patch.

[0081] Referring to FIG. 8B, the assembly 195 is in a second state. In the second state, none of the lower posts are in contact with the first film. Thus, the assembly applies distributed loads 815 and 820 to the smaller inner and outer regions of the substrate 10. To change from the first state to the second state, the assembly 195 can increase the ratio of P2+P3 to P1 and keep P5 smaller than P2+P3. The second state is also called a narrow contact patch to control the polishing rate of the smaller edge area during polishing.

[0082] Referring to FIG. 8C, the assembly 195 is in a third state. In the third state, the outermost lower post 290a is displaced downwards, eventually contacting the first membrane and exerting a concentrated force 825. Thus, the assembly 195 exerts a uniform distributed load 830, 835 in the outer edge region and in the inner edge region, and exerts a concentrated force 825 against the substrate 10. To change to this state from the first state, the assembly 195 increases the ratio of pressure P1 to pressure P2, or P3, or P2+P3, and keeps pressure P5 less than pressure P2. The third state is also called outer weighted point + wide area contact patch to apply higher pressure to the outer etched region, while still exerting pressure over a wide area.

[0083] Referring to FIG. 8D, the assembly 195 is in a fourth state. In the fourth state, the central lower post 290b is displaced downwards, eventually contacting the first membrane and exerting a concentrated force 845. Thus, the assembly 195 exerts a uniform distributed load 840, 850 in the outer edge region and the inner edge region, and exerts a concentrated force 845 against the substrate 10. To change to this state from the first state, the assembly 195 increases the ratio of pressure P5 to pressure P2, P3, or P2+P3. The fourth state is also called central focus+wide area contact patch to apply higher pressure to the central region, while still exerting pressure over a wide area.

[0084] Referring to FIG. 8E, the assembly 195 is in a fifth state. In the fifth state, both the outermost lower post 290a and the central lower post 290b are displaced downwards and contact the first membrane to apply concentrated forces 855, 865. Thus, the assembly 195 applies uniform distributed loads 860, 870 in the outer and inner edge regions of the substrate 10, a concentrated force 855 in the outer edge region, and another concentrated force 865 in the central edge region. To change to this state from the first state, the assembly 195 increases the ratio of pressure P1 to both pressures P2 and P3, and increases the ratio of pressure P5 to P2, or P3, or both P2 and P3. The fifth state is also referred to as an outer and central focused large area contact patch because it applies more concentrated pressure to both the outer and central edge regions.

[0085] Referring to FIG. 8F, the assembly 195 is in a sixth state. In the sixth state, the central lower post 290b is displaced downwards and contacts the first membrane to apply a concentrated force 880. Thus, the assembly 195 applies a uniform distributed load 7875, 885 in the outer edge region and the inner edge region of the substrate 10, and applies a concentrated force 880 in the central edge region of the substrate 10. To change to this state from the first state, the assembly 195 reduces the ratio of pressure P1 to both pressures P2 and P3, and reduces the ratio of pressure P5 to P2, or P3, or both P2 and P3. The sixth state is also referred to as a central weighted + narrow contact patch, which applies a higher pressure to the central edge region, but the overall control area is narrower (compared to FIG. 8D).

[0086] 9A-9C show schematic cross-sectional views of the pressure control assembly 195 of FIG. 4C in various states.

[0087] 4C, the fourth exemplary pressure control assembly 195 includes four chambers: a bladder formed by the actuator 256, and chambers 487, 488, and 489 formed by the first membrane. Optionally, the assembly 195 may include other chambers (not shown) formed by the second membrane 254b of the annular body 254. Each chamber is connected to a respective pressure supply P1, P2, P3, and P4, and the pressures P1, P2, P3, and P4 are variable relative to one another to allow the assembly 195 to reach various states.

[0088] 9A, the assembly 195 is in a first state, in which none of the lower posts are displaced and are not in contact with the first membrane. Thus, in the first state, the assembly 195 applies only distributed pressures 905, 910, and 915 within the three edge regions of the substrate 10. The magnitude of each pressure 905, 910, and 915 is equal to the corresponding pressures P4, P3, and P2. The first state is also referred to as a wide area contact patch.

[0089] Referring to FIG. 9B, the assembly 195 is in a second state. In the second state, none of the lower posts are in contact with the first membrane, and the central chamber 488 is not in contact with the substrate 10. Thus, the assembly 195 applies distributed loads 940 and 945 to two regions of the substrate 10 that have a smaller area (i.e., the inner region and the outer region). To change from the first state to the second state, the assembly 195 can reduce the ratio of pressure P1 to pressure P2, or P4, or P2+P4. Optionally, the assembly 195 can also reduce the ratio of pressure P3 to pressure P1, or P2, or P4, or any combination of P1, P2, and P4. The second state is also called a narrow contact patch to control the polishing rate of a smaller edge area during polishing.

[0090] 9C, the assembly 195 is in a third state. In the third state, the outermost lower posts are displaced downwards and contact the first membrane to apply a concentrated force 925. Thus, the assembly 195 applies uniform distributed loads 920, 930, and 935 in the outer edge region, the central edge region, and the inner edge region of the substrate 10, and applies a concentrated force 825 to the outer edge region of the substrate 10. To change to this state from the first state, the assembly 195 increases the ratio of pressure P1 to pressure P2, and optionally increases the ratio of pressure P1 to pressure P3 or P4. The third state is also referred to as an outer focused large area contact patch to apply a more concentrated pressure to the outer edge region.

[0091] FIG. 10 is a flow diagram illustrating an exemplary edge profile control process 1000 using a pressure control assembly during polishing. The process 1000 may be performed by one or more computers located at one or more locations. Alternatively, the process 1000 may be stored as instructions in one or more computers. Once executed, the instructions may cause one or more components of the polishing apparatus to perform the process. For example, a controller 190 as shown in FIG. 1, or an in-situ monitoring system 160 including the controller 190, may perform the process 1000. In some embodiments, the in-situ monitoring system 160 may include an optical monitoring system, such as a spectroscopic monitoring system. In other embodiments, the in-situ monitoring system 160 may include an eddy current monitoring system.

[0092] 1, the site monitoring system 160 includes a sensor 164 and circuitry 166 connected to the sensor for sending and receiving signals to a controller 190, e.g., a computer. The sensor 164 may be, for example, the end of an optical fiber collecting light for an optical monitoring system, or the core and coil of an eddy current monitoring system. The output of the circuitry 166 may be a digital electronic signal that passes through a rotary coupler 129 (e.g., a slip ring) in the drive shaft 124 to the controller 190. Alternatively, the circuitry 166 could communicate with the controller 190 by wireless signals.

[0093] The system first receives data representing a desired thickness profile of the substrate after polishing. The desired thickness profile may be specified by a user request via a user input interface or may be encoded in a computer program executed by the controller 190. The controller 190 can then determine (1002) a desired thickness of the edge region of the substrate according to the received data.

[0094] The system determines 1004 the measured thickness of the edge region of the substrate. More specifically, for each measurement, the controller 190 can calculate a characteristic value. The characteristic value is typically the thickness of the layer being polished, but can be a related characteristic value such as the thickness to be removed. In addition, the characteristic value can be a physical property other than thickness, such as metal line resistance. In addition, the characteristic value can be more generally representative of the progress of the substrate through the polishing process, for example, an index value representing the time or number of platen rotations at which the spectrum is expected to be observed in the polishing process according to a predetermined progress. The system can then determine the difference between the current polishing rate and the desired polishing rate to reach the desired thickness profile in the edge region of the substrate after polishing.

[0095] In response, the system can periodically adjust the polishing rate. In some embodiments, the system schedules the polishing rate to be adjusted at a predetermined rate, for example, every given number of revolutions, for example, every 5-50 revolutions, or every given number of seconds, for example, every 2-20 seconds. In some ideal situations, the adjustments may be zero at the pre-scheduled adjustment times. In other embodiments, the adjustments may be made at a certain rate determined in-situ. For example, if the measured thickness of the edge region is significantly different from the desired thickness profile, the controller 190 and / or computer can determine frequent adjustments of the polishing rate.

[0096] To adjust the polishing rate at the edge region of the substrate being polished at a given adjustment rate, the controller 190 can apply various combinations of loads of different types and magnitudes after determining the combinations.

[0097] Thus, in response to determining the difference, the system determines a combination of loads to apply to the load areas of the edge region of the substrate (1006). More specifically, the system can determine a combination of load types (concentrated and distributed forces) or assembly modes (e.g., large area contact patch, narrow area contact patch, center weighted large area contact patch, outer weighted large area contact patch, or outer center weighted large area contact patch as described above) to adjust the polishing rate of each edge region of the substrate to achieve substantial within-wafer uniformity after polishing.

[0098] After determining the load magnitude, load type, or assembly mode, the controller 190 controls the valve assembly 189 or the pressure supply tank 181 to vary (1008) one or more pressures in one or more chambers to achieve the determined load or assembly mode. Thus, when polishing a substrate, the polishing rate of each portion of the edge region can be precisely controlled.

[0099] As used herein, the term substrate may include, for example, a production substrate (e.g., including multiple memory or processor dies), a test substrate, a bare substrate, and a gating substrate. The substrate may be at various stages of integrated circuit manufacturing, for example, the substrate may be a bare wafer, or the substrate may include one or more deposited and / or patterned layers. The term substrate may include circular plates and rectangular slabs.

[0100] The polishing apparatus and method described above can be applied in a variety of polishing systems. Either or both of the polishing pad and the carrier head can move to provide relative motion between the polishing surface and the substrate. For example, the platen can orbit rather than rotate. The polishing pad can be a circular (or some other shape) pad fixed to the platen. Some aspects of the endpoint detection system can be applicable to linear polishing systems, for example, where the polishing pad is a linearly moving continuous belt or reel-to-reel belt. The polishing layer can be a standard abrasive material (e.g., polyurethane with or without fillers), a soft material, or a fixed-abrasive material. Although the relative positioning terms are used, it should be understood that the polishing surface and the substrate can be held in a vertical orientation or in some other orientation.

[0101] Control of the various systems and processes described herein, or portions thereof, may be implemented in a computer program product that includes instructions stored on one or more non-transitory computer-readable storage media and executable on one or more processing devices. The systems described herein, or portions thereof, may be implemented as an apparatus, method, or electronic system that may include one or more processing devices and memory storing executable instructions for performing the steps described herein.

[0102] Although the specification contains numerous specific implementation details, these should not be construed as limiting the scope of any invention or what may be claimed, but rather as descriptions of features that may be specific to certain embodiments of a particular invention. Certain features described in the specification in the context of separate embodiments may also be combined and implemented in one embodiment. Conversely, various features described in the context of one embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, although features may be described above as acting in a particular combination and may be claimed as such, one or more features from a claimed combination may, in some cases, be excluded from the combination, and the claimed combination may be directed to a subcombination or a variation of the subcombination.

[0103] Particular embodiments of the present invention have been described.

[0104] Other embodiments are within the scope of the following claims.

Claims

1. 1. A carrier head for holding a substrate in a polishing system, comprising: Housing and a ring-shaped body vertically movable relative to the housing by an actuator, the ring-shaped body including a top portion and at least one lower post projecting downwardly from the top portion; a first annular film secured to extend below the annular body, a lower surface of the first annular film forming at least one pressurizable lower chamber between the first annular film and the annular body to apply a controllable pressure to an edge of a substrate held by the carrier head, the at least one lower post being located within the at least one pressurizable lower chamber, the actuator configured to displace the at least one lower post downwardly to contact and apply a force to an upper surface of the first annular film; at least one pressure supply line connected to the at least one pressurizable lower chamber; A carrier head equipped with

2. The carrier head of claim 1 , wherein the actuator comprises a pressurizable bladder disposed between the housing and the annulus.

3. The carrier head of claim 2 , wherein a bottom surface of the pressurizable bladder includes an annular recess, and the annular body includes an upper annular post extending into the annular recess.

4. The carrier head of claim 3 , wherein the bottom surface of the pressurizable bladder is configured to apply a downward pressure against the upper annular post of the annular body.

5. 3. The carrier head of claim 2, wherein a bottom surface of the first annular membrane is configured to apply pressure to the substrate within a load region, the load region comprising a dimension controlled by pressure in the bladder and pressure in the at least one pressurizable lower chamber.

6. 2. The carrier head of claim 1 , wherein the annular body includes a top portion for engaging the actuator and a second annular membrane secured to the top portion and defining a first chamber, the at least one lower post being secured to a bottom portion of the second annular membrane, the second annular membrane configured to deform downwardly in response to an increase in pressure in the first chamber to displace the at least one lower post downwardly.

7. The carrier head of claim 6 , wherein the actuator includes a pressurizable bladder, an upper post projecting vertically upwardly from an upper surface of the second annular membrane into the bladder.

8. The carrier head of claim 6 , wherein the at least one lower post does not contact the top surface of the first annular membrane when pressure in the first chamber is elevated.

9. 7. The carrier head of claim 6, wherein the at least one lower post comprises a first lower post secured to an end of the annular body and a second lower post secured to a bottom of the second annular membrane.

10. The carrier head of claim 9 , wherein the first lower post includes an inwardly projecting flange.

11. 2. The carrier head of claim 1 , wherein the at least one pressurizable lower chamber comprises two chambers, each of the two chambers connected to a respective pressure supply via one of a plurality of the pressure supply lines.

12. The carrier head of claim 1 , wherein the at least one lower post includes an inwardly projecting flange.

13. The carrier head of claim 1 , wherein the at least one lower post is secured to an end of the annulus.

14. The carrier head of claim 13 , wherein the at least one lower post includes an inwardly projecting flange.

15. 2. The carrier head of claim 1 , wherein the at least one pressurizable lower chamber includes three chambers, each of the three chambers surrounding one of the at least one lower post, and each of the three chambers connected to a respective pressure supply via one of a plurality of the pressure supply lines.

16. 2. The carrier head of claim 1, comprising a plurality of pressure supplies, each pressure supply of the plurality of pressure supplies coupled to a corresponding pressure supply line of the plurality of pressure supply lines, each pressure supply capable of separately adjusting pressure in a corresponding pressurizable lower chamber of the plurality of pressurizable lower chambers.

17. The carrier head of claim 1 , wherein the first annular membrane is made of an elastomer.

18. The carrier head of claim 1 , wherein the first annular membrane is made of plastic.

19. 2. The carrier head of claim 1, wherein the first annular film is configured to contact an area on the top surface of the substrate, the area extending radially inward as a ring shape having a width of 4-6 mm starting from an edge of the substrate.

20. 1. A carrier head for holding a substrate in a polishing system, comprising: Housing and a first annular membrane extending below the housing; and means for controlling a size of a load area over which a combination of loads is applied to the substrate, the combination of loads including pressure and a concentrated force applied by at least one lower post contacting the first annular film; means for controlling the pressure applied to the substrate within the load region; means for controlling the concentrated force applied to the substrate within a concentrated area within the load area; Including, career head.

21. a first annular membrane secured to extend below the annular body, the first annular membrane defining at least one pressurizable lower chamber between the first annular membrane and the annular body, the at least one lower post being located within the at least one pressurizable lower chamber; the size of the load area is controlled by a shape of the at least one pressurizable lower chamber, the shape being changeable based on a pressure in the at least one pressurizable lower chamber; The carrier head of claim 20 , wherein the focused force applied to the substrate is controlled based at least in part on the pressure in the at least one pressurizable lower chamber.

22. 22. The carrier head of claim 21 , wherein the at least one lower post is configured to contact an upper surface of the first annular membrane and apply the concentrated force against the upper surface based at least in part on the pressure in the at least one pressurizable lower chamber.

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