Cleaning system for polishing liquid transfer arm

Abstract

A cleaning system for a polishing liquid transfer arm is disclosed. A polishing assembly includes: a rotatable table to support a polishing pad; a polishing liquid transfer arm having an enclosure open at the bottom and one or more ports to transfer a polishing liquid and a cleaning fluid downward through the interior space of the enclosure onto the polishing pad; and a transfer arm cleaning tool removably attached to the polishing liquid transfer arm, the cleaning tool extending below the transfer arm and having a surface facing the transfer arm, the cleaning tool being shaped such that the cleaning tool directs a cleaning fluid from the polishing liquid transfer arm onto a surface of the enclosure of the polishing liquid transfer arm.

Description

[0001] This application is a divisional application of the application patent application with application number 202180042188.4, title "Cleaning system for polishing liquid delivery arm", and filing date June 24, 2021. TECHNICAL FIELD

[0002] The present disclosure relates to chemical mechanical polishing, and in particular to cleaning of a polishing liquid delivery arm that delivers polishing liquid onto a polishing pad. BACKGROUND

[0003] Integrated circuits are typically formed on a substrate by sequentially depositing conductive, semiconductive, or insulative layers on a silicon wafer. One fabrication step during the manufacture of integrated circuits is to polish a filler layer to expose the top surface of an underlying insulative layer, for example, to form vias, plugs, and lines that provide conductive paths between thin film circuits on the substrate. For other applications, such as oxide polishing, a filler layer is planarized until a predetermined thickness is left on a non-planar surface. In addition, planarization of a substrate surface is often required for photolithography.

[0004] Chemical mechanical polishing (CMP) is an accepted planarization method. This planarization method typically requires that a substrate be secured on a carrier or polishing head. An exposed surface of the substrate is typically placed against a rotating polishing pad. The carrier head provides a controllable load on the substrate to push the substrate against the polishing pad. A polishing liquid is typically supplied to the surface of the polishing pad by a polishing liquid delivery arm. The polishing liquid delivery arm can also have a nozzle to spray a cleaning fluid onto the polishing pad to remove slurry or debris from the polishing surface. SUMMARY

[0005] In one aspect, a polishing assembly includes a rotatable platen to support a polishing pad, a polishing liquid delivery arm having an enclosure open at a bottom and one or more ports to deliver polishing liquid and cleaning fluid down through an interior space of the enclosure to the polishing pad, and a delivery arm cleaning tool removably attached to the polishing liquid delivery arm, the cleaning tool extending below the delivery arm and having a delivery arm-facing surface shaped such that the cleaning tool directs the cleaning fluid from the polishing liquid delivery arm onto a surface of the enclosure of the polishing liquid delivery arm.

[0006] In another aspect, a polishing liquid delivery arm cleaning tool has a delivery arm cleaning tool including an arm-facing surface shaped to direct cleaning fluid projected downward from a polishing liquid delivery arm onto an inner surface of an enclosure of the polishing liquid delivery arm, and a retaining tab configured to secure the delivery arm cleaning tool to the polishing liquid delivery arm.

[0007] In another aspect, a polishing liquid delivery arm cleaning tool includes a main body configured to be removably secured to a polishing liquid delivery arm of a chemical mechanical polishing system, and an insert removably secured to the main body. The insert has an arm-facing surface shaped to direct cleaning fluid from the polishing liquid delivery arm back onto an inner surface of an enclosure of the polishing liquid delivery arm.

[0008] In another aspect, a method of cleaning a polishing liquid delivery arm includes installing a polishing liquid delivery arm cleaning tool to extend below an enclosure of a polishing liquid delivery arm, flowing cleaning fluid through the polishing liquid delivery arm, and directing the cleaning fluid from the polishing liquid delivery arm away from a surface of the cleaning tool back onto a surface of the enclosure of the polishing liquid delivery arm.

[0009] Embodiments can optionally include, but are not limited to, one or more of the following advantages. Polishing quality can be improved, for example, with less scratching and defects caused by dry abrasive particles accumulated from polishing slurry dislodged from a polishing liquid delivery arm during a polishing process. In addition, the number of substrates rejected due to defects can be reduced. Maintenance downtime for a polishing system can be significantly reduced. The quality of the cleaning process can be improved, and locations on a polishing liquid delivery arm that are difficult to reach can be more easily cleaned. This improves the productivity of a polishing system, and reduces the time of an operator as less time is focused on polishing liquid delivery arm cleaning processes. The cleaning process can be quickly modified by adjusting cleaning fluid pressure or cleaning fluid composition.

[0010] 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 DRAWINGS

[0011] Figure 1A A schematic cross-sectional view of a chemical mechanical polishing system is shown.

[0012] Figure 1B A schematic cross-sectional view of a polishing liquid delivery arm cleaning tool installed on a polishing liquid delivery arm of the chemical mechanical polishing system of FIG. 1 is shown.

[0013] Figure 2A perspective view of a polishing liquid transfer arm cleaning tool installed on the polishing liquid transfer arm of a chemical mechanical polishing system.

[0014] Figure 3A Figure 1 shows a cross-sectional view of the polishing liquid transfer arm of the chemical mechanical polishing system.

[0015] Figure 3B show Figure 2 A 3D view of a polishing liquid transfer arm cleaning tool.

[0016] Figure 3C A cross-sectional view of a polishing liquid transfer arm cleaning tool fixed to the polishing liquid transfer arm is shown.

[0017] Figure 4 show Figure 2 Rear perspective view of a polishing liquid transfer arm cleaning tool with a pocket.

[0018] Figure 5 show Figure 2 A cross-sectional view of the polishing liquid transfer arm cleaning tool.

[0019] Figure 6A A perspective view showing another embodiment of a polishing liquid transfer arm cleaning tool installed on the polishing liquid transfer arm of a chemical mechanical polishing system.

[0020] Figure 6B show Figure 6A A cross-sectional view of the polishing liquid transfer arm cleaning tool.

[0021] Figure 7A A perspective view showing the lower portion of another embodiment of the polishing liquid transfer arm cleaning tool.

[0022] Figure 7B show Figure 7A A cross-sectional view of the polishing liquid transfer arm cleaning tool.

[0023] Figure 8 This demonstrates a method for cleaning and polishing liquid transfer arms.

[0024] Similar reference numerals and symbols are used to indicate similar elements in the various figures. Detailed Implementation

[0025] During chemical mechanical polishing, a polishing liquid such as a polishing slurry is supplied to the surface of the polishing pad by a polishing liquid delivery arm. For example, the polishing liquid delivery arm can have a nozzle that dispenses the polishing liquid onto the surface of the polishing pad. As the polishing liquid impacts the polishing pad, some of the polishing liquid can deflect upward and form airborne droplets. These droplets can accumulate on the polishing liquid delivery arm. In addition, the polishing liquid can scatter off the polishing pad by other components, such as a carrier head or a conditioner head.

[0026] While some of the polishing liquid will flow off the delivery arm and can be collected in a basin, some of the polishing liquid can dry and accumulate on the delivery arm. The accumulation of dried polishing liquid on the delivery arm over time has multiple deleterious effects. For example, abrasive particles in the polishing liquid can form agglomerates that can later fall off the delivery arm and deposit onto the polished surface, thereby causing scratches and defects. Significant non-productive time and operator effort is required to clean the polishing liquid delivery arm to avoid the accumulation of dried polishing liquid.

[0027] A polishing liquid delivery arm cleaning tool that can be easily added to the polishing liquid delivery arm and does not require equipment disassembly can mitigate these deleterious effects.

[0028] Figure 1A A polishing system 20 is shown that is operable to polish a substrate 10. The polishing system 20 includes a rotatable platen 24 on which a polishing pad 25 is disposed, and a platen shield 26 that surrounds the rotatable platen 24. The rotatable platen 24 is operable to rotate about an axis 28. For example, a motor 29 can turn a drive shaft 22 to rotate the rotatable platen 24.

[0029] The polishing system 20 includes a carrier head 70 that is operable to hold the substrate 10 against the polishing pad 25. The carrier head 70 is suspended from a support structure 72, such as a carousel or a track, and is connected to a carrier head rotation motor 76 by a carrier drive shaft 74 so that the carrier head is rotatable about an axis 71. In addition, the carrier head 70 can oscillate laterally across the polishing pad 25, for example, by actuator-driven movement in a radial slot in the carousel 72, by motor-driven rotation of the carousel, or by actuator-driven fore-aft movement along a track. In operation, the platen 24 rotates about its central axis 28, and the carrier head rotates about its central axis 71 and translates laterally across the top surface of the polishing pad 25.

[0030] As shown in FIG. 1, the polishing system 20 also includes a polishing liquid delivery system 30. The polishing liquid delivery system 30 includes a polishing liquid delivery arm 34 supported above the worktable 24 by a base 32. A port 38, which can be located at the end of the arm 34, is coupled to a polishing liquid source 78 (e.g., a reservoir) by a fluid line 68 (e.g., a pipe, tube, passage, etc. through a solid body). The port 38 can be a nozzle. During polishing, the delivery arm 34 is operable to dispense polishing liquid 36 from the port 38. The flow of polishing liquid 36 through the fluid line 68 can be controlled by a liquid flow controller (LFC), which in turn can be controlled by a machine controller (e.g., a computer).

[0031] The polishing system 20 also includes one or more second ports 82, which can be located at the end of the arm 34 or positioned along the arm. The second ports 82 are coupled to a cleaning fluid source 86 (e.g., a reservoir) by a fluid line 84 (e.g., a pipe, tube, passage, etc. through a solid body). During cleaning, the delivery arm 34 is operable to dispense cleaning fluid 88 from the ports 82. The second ports 82 can be nozzles, and the nozzles can spray cleaning fluid onto the polishing pad 25. The cleaning fluid can be water, deionized water, or an isopropyl alcohol solution. The flow of cleaning fluid 88 through the fluid line 78 can be controlled by a liquid flow controller (LFC), which in turn can be controlled by a machine controller (e.g., a computer).

[0032] Referring to Figure 3A The polishing liquid delivery arm 34 can form an enclosure 26 that is open at the bottom 40. In particular, the polishing liquid delivery arm 34 includes a roof 44 and sidewalls 46 that extend downward from the roof 44. The interior space 42 is between a ceiling 80 provided by the bottom of the roof 44 and the interior surfaces 58 of the sidewalls 46.

[0033] During a cleaning operation, the cleaning fluid liquid 36 flows downward through the interior space 42 of the enclosure 26 to the polishing pad 25. The enclosure 26 can be helpful to contain the spray of cleaning fluid from the ports 82 and / or off of the polishing pad 25.

[0034] In other embodiments, the port in the polishing liquid delivery arm 34 can be switched between delivering polishing liquid 36 and cleaning fluid 82. In other embodiments, the polishing liquid delivery arm 34 can have one nozzle, e.g., at the end of the arm 34, that is configured to be switched between delivering polishing liquid 36 and cleaning fluid 82.

[0035] Although Figure 3AThe polishing fluid line 68 and cleaning fluid line 84 are illustrated as pathways within the solid body, but this is not mandatory. One or both fluid lines may be provided from inside the cavity of the arm, or from tubes or flexible conduits on top of the arm.

[0036] Polishing liquid 36 can be a slurry containing abrasive particles. Polishing liquid 36 is dispensed through nozzle 38 via polishing liquid transfer arm 34. Nozzle 38 guides polishing liquid 36 onto the surface of polishing pad 10. As polishing liquid 36 impacts polishing pad 25, some polishing liquid 36 may reflect upwards and form droplets. Although some polishing liquid 36 will flow away from polishing arm 34 and return to polishing pad 25 and can be collected in a basin, some polishing liquid 36 may dry and accumulate on polishing liquid transfer arm 34, for example, on the inner surface 58 of sidewall 46, on top surface 80, and on nozzle 38. Subsequent polishing operations will continue to deposit polishing liquid 36 on polishing liquid transfer arm 34, and polishing liquid 36 may dry and further accumulate on polishing liquid transfer arm 34.

[0037] The polishing liquid transfer arm cleaning tool 50 can be removably attached to the transfer arm 34. In general, the cleaning tool 50 forms a housing that, when mounted on the transfer arm, covers at least the bottom of the enclosure 26. Figure 1B and Figure 2 This shows a polishing liquid transfer arm cleaning tool 50 mounted on the polishing liquid transfer arm 34. When installed, the cleaning tool 50 extends below the transfer arm 34. In this configuration, the cleaning fluid 88 flows downwards, through the internal space 42 of the enclosure 26, and impacts the polishing liquid transfer arm cleaning tool 50, such as... Figure 1B As shown in the figure, it is redirected to the top surface 80 inside the polishing liquid transfer arm 37.

[0038] The polishing liquid transfer arm cleaning tool 50 has a floor 52 and a sidewall 54 extending upward from the floor 52. When installed, the floor 52 extends below the polishing liquid transfer arm 34 and across the width of the polishing liquid transfer arm 34, and the sidewall 54 extends along the outer surface 56 of the transfer arm 36.

[0039] The cleaning tool 50 may include a plurality of retaining tabs 60 to support the cleaning tool on the arm 34. Each retaining tab 60 may extend from the sidewall 54 and bend inward, i.e., bend toward the opposite sidewall. Thus, when the cleaning tool 50 slides onto the arm 34, the retaining tabs 60 extend over the top 44 of the polishing liquid transfer arm 34 to secure the cleaning tool 50 to the polishing liquid transfer arm 34 (see [link to relevant documentation]). Figure 3C ).

[0040] The front end of the cleaning tool 50 is enclosed by a front cover 62. The front cover 62 is connected to the sidewalls 54 and extends over the space between the sidewalls 54, into which the arm 34 is fitted. The front cover 62 prevents cleaning fluid from splashing out of the front of the cleaning tool 50. The rear end of the cleaning tool 50 is open, allowing the cleaning tool to slide onto the arm 34. Apart from the front cover 62, the cleaning tool 50 may be open at the top.

[0041] like Figure 4 As shown, the polishing liquid cleaning tool 50 has a surface 48 facing the transfer arm, configured such that the polishing liquid transfer arm cleaning tool 50 guides cleaning fluid from the polishing liquid transfer arm 34 onto the inner surface 58 of the sidewall 46, onto the top surface 80, and onto the nozzle 38 of the polishing liquid transfer arm 34. The arm-facing surface 48 may have one or more concave surfaces 64 to guide the cleaning fluid upward back to the inner surfaces of the enclosure (e.g., the top surface 80 and the inner surface 58 of the sidewall 46).

[0042] like Figure 4 As shown, concave surface 64 can be a semi-circular trough. Or, as... Figure 5 As shown, the concave surface 64 can be cylindrical. The curvature of the concave surface 64 is configured such that the initial momentum of the droplets of the downward-traveling cleaning fluid 88 will carry the droplets 88 around the curve and back upward to the inner surface 58 of the top surface 88 and the wall. In some embodiments, a ridge 90 separates one concave surface 64 from another. A concave surface 64 can be separated from another concave surface by more than one ridge. For example, a second ridge 92 can extend in a direction perpendicular to the ridge 90. The ridge 90 can be located directly below the nozzle 38 to split the spray of the cleaning fluid 88, such that a portion of the spray is redirected to one location and another portion is redirected to another location, such that half of the spray is directed to each side of the inner surface 58 of the polishing liquid transfer arm 34 nozzle 38 and the top surface 88 and the side wall 46.

[0043] In some implementations, the surface 48 facing the arm is the top surface of the body 52.

[0044] In some implementations, body 52 may be configured to receive insert 66 (see...) Figure 3C The insert 66 is removably secured to the body 52. ​​For example, the insert 66 can slide into the guide groove 48a on the top of the body 52 (see...). Figure 3B The surface 48 facing the arm can be the top surface of the insert 66, so that the insert 66 guides the cleaning fluid from the polishing fluid transfer arm 34 back to the inner surface 58 of the polishing fluid transfer arm and the nozzle 38.

[0045] Reference Figure 6A and6B Replacing the main body suspended from the earpiece, the polishing liquid cleaning tool 50 may include an upper cover 110 and a lower cover 120, which are detachably fixed together to form a complete surround (e.g.) Figure 6B As shown in the diagram, the housing of the polishing liquid transfer arm 34 (transverse to the length of the arm) is shown. For example, the upper cover 110 may include a sidewall 112 extending downward from the edge of the top member 114, and the lower cover 120 may include a sidewall 122 extending upward from the edge of the base member 124. The sidewall 112 of the upper cover 110 may be attached to the sidewall 122 of the lower cover 120, for example, by friction fit 130. The front cover 62 of the cleaning tool 50 may similarly be provided by the sidewalls 112, 122 of the upper and lower covers 110, 120. For assembly, the lower cover 110 may be positioned below the polishing liquid transfer arm 34, and the upper cover 120 may be lowered into position to engage with the lower cover 110, thereby enclosing the arm 34.

[0046] Reference Figure 7A and 7B The bottom plate component 124 of the lower cover 120 (or Figures 3A-3B The base plate of the single-piece tool 50 may include one or more channels 140 for draining excess cleaning fluid from the tool 50. In some embodiments, there are two channels 140, each on a separate side of the insert 48. The channels 140 may be adjacent to the sidewalls 122. In particular, two parallel linear protrusions 142 may extend from the base plate member 124, and the space between the protrusions 142 and the sidewalls 122 provides the channels 140. The insert 66 may be fitted onto the base plate member 124 and between the two protrusions 142. One end of each channel is blocked by a front cover 62, but cleaning fluid can drain from the opposite end.

[0047] The polishing liquid transfer arm cleaning tool 50 can be made of metal or plastic. For example, the cleaning tool 50 can be made of steel, aluminum, high-density polyethylene, or composite materials.

[0048] Figure 8A method 600 for cleaning a polishing liquid transfer arm using a polishing liquid transfer arm cleaning tool is shown. An insert is inserted into the cleaning tool (802). The insert has an arm-facing surface configured such that it guides cleaning fluid from the polishing liquid transfer arm back to the surface of the polishing liquid transfer arm. The insert may have multiple recesses to guide the cleaning fluid. The polishing liquid transfer arm cleaning tool is mounted on the polishing liquid transfer arm such that the arm-facing surface extends below the enclosure of the polishing liquid transfer arm (804). The polishing liquid transfer arm cleaning tool retains lugs engaged above the top of the polishing liquid transfer arm. Cleaning fluid flows through the polishing liquid transfer arm (806). The cleaning fluid is guided by the arm-facing surface back to the surface of the enclosure of the polishing liquid transfer arm (808). The polishing liquid transfer arm cleaning tool is removed from the polishing liquid transfer arm (810).

[0049] Several embodiments have been described. However, it should be understood that various modifications can be made. Therefore, other embodiments are within the scope of the appended claims.

Claims

1. A polishing liquid delivery arm cleaning apparatus comprising: a delivery arm cleaning tool configured to be removably secured to a polishing liquid delivery arm, the delivery arm cleaning tool comprising an upper cover for removably fitting over a polishing liquid delivery arm; a lower cover for removably fitting under the polishing liquid delivery arm and being detachably secured to the upper cover to form an enclosure around the polishing liquid delivery arm; and an arm-facing surface shaped to direct cleaning fluid projected downward from a polishing liquid delivery arm back onto an inner surface of an enclosure of the polishing liquid delivery arm.

2. The apparatus of claim 1, wherein the upper cover and the lower cover are detachably secured by a friction fit.

3. The apparatus of claim 1, wherein the delivery arm cleaning tool comprises an insert removably supported by the lower cover, the insert having the arm-facing surface.

4. The apparatus of claim 3, wherein a floor of the lower cover comprises a first linear protrusion extending parallel to a first sidewall of the lower cover and a second linear protrusion extending parallel to a second sidewall of the lower cover, and a space between the first linear protrusion and the first sidewall provides a first channel and a space between the second linear protrusion and the second sidewall provides a second channel.

5. The apparatus of claim 4, wherein the insert fits between the first linear protrusion and the second linear protrusion on the floor of the lower cover.

6. The apparatus of claim 1, wherein the lower cover comprises at least one channel for draining cleaning liquid from an open end of the enclosure.

7. The apparatus of claim 1, wherein the arm-facing surface has a plurality of concavities to direct the cleaning fluid.

8. The apparatus of claim 7, wherein the plurality of concavities comprises two semicircular troughs extending in parallel to sidewalls of the enclosure.

9. The apparatus of claim 7, wherein a ridge between the two semicircular troughs is positioned below a cleaning fluid nozzle of the polishing liquid delivery arm.

10. A polishing liquid delivery arm cleaning apparatus comprising: a delivery arm cleaning tool configured to be removably secured to a polishing liquid delivery arm, the delivery arm cleaning tool comprising a body having a floor, a pair of sidewalls, and tabs protruding upward from the sidewalls to extend over a top of a polishing liquid delivery arm to removably secure the body to the polishing liquid delivery arm; and an arm-facing surface shaped to direct cleaning fluid projected downward from a polishing liquid delivery arm back onto an inner surface of an enclosure of the polishing liquid delivery arm. ​ 11. The apparatus of claim 10, wherein the transfer arm cleaning tool comprises an insert removably secured to the main body, the insert having an arm-facing surface configured to direct cleaning fluid from the polishing liquid transfer arm onto an inner surface of an enclosure of the polishing liquid transfer arm.

12. The apparatus of claim 10, wherein the arm-facing surface has a plurality of concavities to direct the cleaning fluid.

13. The apparatus of claim 12, wherein the plurality of concavities comprises two semi-circular valleys extending in parallel to the side walls of the housing.

14. The apparatus of claim 10, wherein the arm-facing surface has a first ridge extending in parallel to the side walls of the housing.

15. The apparatus of claim 14, wherein the arm-facing surface comprises a plurality of second ridges extending perpendicular to the first ridge.

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