Insulating fluid line in chemical mechanical polishing

Abstract

A polishing assembly includes a chemical mechanical polishing system, a fluid source, and a fluid transfer conduit to carry fluid from the fluid source into the chemical mechanical polishing system. The chemical mechanical polishing system includes a platen to support a polishing pad, a carrier head to support a substrate and bring the substrate into contact with the polishing pad, and a motor to cause relative motion between the platen and the carrier head. The fluid transfer conduit includes an electrically insulating tube, an electrically conductive wrap wound around an outer diameter of the tube from a first end of the tube to a second end of the tube, and an electrically conductive wire attached to the first end of the electrically conductive wrap. The electrically conductive wrap is configured to conduct electrostatic discharge, and the electrically conductive wire is configured to conduct the electrostatic discharge from the electrically conductive wrap to a ground source.

Description

Technical Field

[0001] This disclosure relates to chemical mechanical polishing (CMP), and more specifically to fluid transport in CMP. Background Technology

[0002] Integrated circuits are typically formed on a substrate by sequentially depositing conductive, semiconducting, or insulating layers on a semiconductor wafer. Various fabrication processes require planarization layers on the substrate. For example, one fabrication step involves depositing a fill layer on a non-planar surface and then planarizing the fill layer. For some applications, the fill layer is planarized until the top surface of the patterned layer is exposed, or until a predetermined thickness of material is left on the underlying layer.

[0003] Chemical mechanical polishing (CMP) is an acceptable planarization method. This planarization method typically requires mounting a substrate on a carrier head. The exposed surface of the substrate is usually positioned against a rotating polishing pad. The carrier head provides a controlled load on the substrate to push it against the polishing pad. A polishing slurry containing abrasive particles is typically supplied to the surface of the polishing pad. For example, a cleaning fluid such as deionized water can be sprayed onto the polishing pad to remove debris from the polishing process. Summary of the Invention

[0004] In one aspect, the polishing assembly includes: a chemical mechanical polishing (CMP) system, a fluid source, and a fluid transport conduit for carrying fluid from the fluid source to the CMP system. The CMP system includes: a platform for supporting a polishing pad, a support head for supporting a substrate and bringing the substrate into contact with the polishing pad, and a motor for causing relative movement between the platform and the support head. The fluid transport conduit includes: an electrically insulating tube; a conductive winding wound around the outer diameter of the tube from a first end to a second end, the conductive winding configured to allow electrostatic discharge to flow; and a conductive wire attached to the first end of the conductive winding, the conductive wire configured to conduct electrostatic discharge from the conductive winding to a ground source.

[0005] In another embodiment, an electrically insulating tube is configured to allow fluid to flow into a chemical mechanical polishing system, comprising: a conductive winding wound around the outer diameter of the tube from a first end to a second end, the conductive winding being configured to conduct electrostatic charge; and a conductive wire attached to the conductive winding, the conductive wire being configured to conduct electrostatic charge from the conductive winding to a common ground source.

[0006] In another aspect, a method of manufacturing a fluid conduit includes: wrapping a conductive winding around a tube, and coupling a conductive wire to the conductive winding. The tube is configured to allow fluid to flow into a chemical mechanical polishing assembly, and the conductive winding is configured to form an electrostatic discharge protection assembly for conducting electrostatic charges.

[0007] The implementation may include one or more of the following features: The fluid source may include a reservoir for holding a clean liquid. The fluid can flow through an electrostatic discharge (ESD) protection component. In response to flowing the fluid through the ESD protection component, an electrostatic charge may be generated on the pipe. The electrostatic charge may discharge from the pipe through a conductive winding to a conductive wire to a common ground source.

[0008] Possible advantages may include, but are not limited to, one or more of the following.

[0009] This reduces the risk of electrostatic discharge from fluid transport lines, and thus reduces damage to other components in the fluid transport lines or chemical mechanical polishing systems. The insulating tube can be easily and cost-effectively manufactured. There is no additional risk of contamination for the fluid flowing through the tube.

[0010] Details of one or more embodiments are set forth in the accompanying drawings and the following description. Other aspects, features, and advantages will be apparent from the description and drawings and from the claims. Attached Figure Description

[0011] Figure 1 This is a schematic cross-sectional view of an example of a polishing system for a polishing apparatus.

[0012] Figure 2 This is a schematic top view of an example polishing system for a chemical mechanical polishing apparatus.

[0013] Figure 3 This is a schematic partial cross-sectional perspective view of a tube having an electrostatic discharge protection assembly for a conduit in a chemical mechanical polishing system.

[0014] Figure 4A This is a schematic cross-sectional front view of the tube.

[0015] Figure 4B This is a schematic cross-sectional side view through the end of the pipe.

[0016] In various accompanying figures, similar reference numerals indicate similar elements. Detailed Implementation

[0017] Chemical mechanical polishing (CMP) systems comprise a significant number of fluid transport lines for carrying substantial amounts of fluids, such as deionized water, steam, and nitrogen. For example, a typical system may include fluid transport lines for carrying slurry to the polishing pad, for carrying cleaning liquid to the polishing pad to remove polishing debris, for carrying heated or cooled fluid to the polishing pad to control the temperature of the polishing process, for carrying pressurized gas for pneumatically controlling pressure in the bearing head, and so on. Static electricity that builds up in these fluid transport lines can be caused by triboelectric charging or by electrostatic induction. If the built-up static electricity becomes too large, it can lead to electrostatic discharge, damaging components and tubing along the fluid transport lines. Specifically, static electricity tends to occur specifically in fluid lines carrying hot gases, such as steam. The combination of steam and temperature can lead to triboelectric charging, which is not observed in conventional systems that do not use steam.

[0018] The conventional approach for electrostatic dissipation (ESD) tubes is to place a conductive layer, such as a carbon conductive layer, on the inside of the tube. However, particles of the material coating the inside of the tube can be carried by the fluid to the polishing system, leading to contamination and defects on the substrate. Furthermore, the polishing environment can be wet and damp due to the splashed slurry, so the conductive layer on the outside of the tube can be subjected to oxidation or environmental degradation.

[0019] A potentially suitable technique is to use a polymer tube wound with a conductive material and having a heat-shrinkable tube subsequently applied to the conductive material. The conductive material can then be grounded.

[0020] Figure 1 and Figure 2 An example of a polishing system 20 in a chemical mechanical polishing system is shown. The polishing system 20 includes a rotatable disc-shaped platform 24 on which a polishing pad 30 is disposed. The platform 24 is operable to rotate about an axis 25 (see [link to diagram]). Figure 2 (See arrow A in the diagram). For example, motor 22 can rotate drive shaft 28 to rotate platform 24. Polishing pad 30 can be a two-layer polishing pad with an outer polishing layer 34 and a softer backing layer 32.

[0021] The polishing system 20 may include a supply port 40 (e.g., at the end of a slurry dispensing arm 43) for dispensing polishing liquid 42 (such as abrasive slurry) onto the polishing pad 30. The polishing liquid may be transferred from a reservoir 44, for example, via a pump through a fluid transfer line 46.

[0022] Polishing system 20 may include a regulating disk 92 (see Figure 2 A controller 90 is used to maintain the surface roughness of the polishing pad 30. An adjustment disc 92 can be positioned in an adjustment head 93 at the end of the arm 94. The pressure adjustment disc 92 against the polishing pad 30 can be pneumatically controlled in a fluid transmission line 96, for example by pressurized gas (e.g., N2).

[0023] The support head 70 is operable to hold the substrate 10 against the polishing pad 30. The support head 70 may also include a retaining ring 56 for maintaining the lateral position of the substrate below the support head. The support head 70 is suspended from a support structure 60 (e.g., a turntable or track) and connected to a support head rotation motor 64 via a drive shaft 62, allowing the support head to rotate about axis 51. Alternatively, the support head 70 may be laterally oscillated by movement along a track, for example, on a slider of a turntable, or by the rotational oscillation of the turntable itself.

[0024] The bearing head 70 may include a flexible membrane 54 having a substrate mounting surface to contact the back side of the substrate 10, and a plurality of pressurizable chambers 52a-52c for applying different pressures to different areas (e.g., different radial areas) on the substrate 10. The pressure on the pressurizable chambers 52a-52c may be controlled by pressure regulators 58a-58c. The pressure regulators 58a-58c may be coupled via pneumatic lines 59, which carry pressurized gas (e.g., N2) to the respective pressurizable chambers 52a-52c via rotary joints and drive shafts 62.

[0025] During operation, the platform rotates about its central axis 25, and the bearing head rotates about its central axis 51 (see...). Figure 2 Arrow B in the image), and laterally translated across the top surface of polishing pad 30 (see...). Figure 2 Arrow C in the diagram.

[0026] As the carrier head 70 and adjusting head 93 sweep across the polishing pad 30, any exposed surface tends to become covered with slurry. For example, the slurry may adhere to the outer or inner diameter surface of the retaining ring 56. Generally, for any surface not maintained in a wetted state, the slurry will tend to solidify and / or dry, resulting in partial corrosion and particles and defects on the substrate. One solution is to clean components, such as the carrier head 70 and adjusting head 93, (e.g., by spraying with water or steam). A carrier head cleaner (e.g., a steam disposal assembly) for the carrier head can be part of the loading shroud in the polishing system. Similarly, an adjusting head cleaner (e.g., a steam disposal assembly) for the adjusting head can be part of the adjusting head cleaning shroud. In either case, tubing is required to carry the cleaning fluid (e.g., liquid water or steam) to the cleaner.

[0027] In some embodiments, the polishing system 20 includes a temperature sensor 80 for monitoring the temperature of components in or within the polishing station, such as the polishing pad 30 and / or the polishing fluid on the polishing pad. For example, the temperature sensor 80 may be an infrared (IR) sensor, such as an IR camera. Alternatively or additionally, the temperature sensor may be a contact sensor rather than a non-contact sensor. For example, the temperature sensor 80 may be a thermocouple or IR thermometer positioned on or within the platform 24. Furthermore, the temperature sensor 80 may be in direct contact with the polishing pad.

[0028] The polishing system 20 may also include a temperature control system 100 for controlling the temperature of the polishing pad 30 and / or the polishing liquid on the polishing pad. The temperature control system 100 may include a cooling system 102 and / or a heating system 104. At least one of the cooling system 102 and the heating system 104, or both in some embodiments, operate by transferring a temperature-controlled medium (e.g., liquid, steam, or spray) to the polishing surface 36 of the polishing pad 30 (or to the polishing liquid already present on the polishing pad).

[0029] like Figure 1 As shown, the example temperature control system 100 includes one or more arms 110 extending over a platform 24 and a polishing pad 30. A plurality of nozzles 120 are suspended from or formed in each arm 110, and each nozzle 120 is configured to deliver temperature-controlled fluid to the polishing pad 30, for example, to spray fluid onto the polishing pad.

[0030] For operation as a cooling system, the temperature control fluid is a coolant. The coolant is a gas (e.g., air) or a liquid (e.g., water). The coolant can be at room temperature or condense below room temperature, for example, in the range of 5-15°C. The coolant used in cooling system 102 may include, for example, chilled water, liquid nitrogen, or a gas formed from liquid nitrogen and / or dry ice. In some embodiments, droplets of a liquid (e.g., water, ethanol, or isopropanol) may be added to the gas stream. In some embodiments, the cooling system uses a spray of air and liquid, for example, an atomized spray of a liquid (e.g., water). Specifically, the cooling system may have nozzles that produce an atomized spray of water that condenses below room temperature.

[0031] like Figure 2 As shown, the cooling system 102 may include a source 130 for a liquid coolant medium and / or a source 132 for a gaseous coolant medium. Before being directed through nozzle 120 (e.g., to form spray 122), liquid from source 130 and gas from source 132 may be carried by pipes 134, 136 to arm 110 and its interior. When dispensed, this coolant may be below room temperature, for example, from -100 to 20°C, for example, below 0°C.

[0032] Gas (e.g., compressed gas) from gas source 132 can be connected to a vortex tube 50 that can separate the compressed gas into cold vapor and hot vapor, and direct the cold vapor to nozzle 120 onto polishing pad 30. In some embodiments, nozzle 120 is the lower end of the vortex tube that directs the cold vapor of the compressed gas onto polishing pad 30.

[0033] For operation as a heating system, the temperature control fluid is a heated fluid. The heating fluid can be a gas (e.g., steam or heated air), a liquid (e.g., heated water), or a combination of gas and liquid. The heating fluid is above room temperature, for example, between 40 and 120°C, or, for example, between 90 and 110°C. The fluid can be water (e.g., substantially pure deionized water) or water including additives or chemicals. In some embodiments, the heating system uses vapor spraying, or a combination of vapor and liquid water. The vapor may include additives or chemicals.

[0034] like Figure 2 As shown, the heating system 104 may include a source 140 for heating a liquid (e.g., hot water) and / or a source 142 for heating a gas (e.g., steam). For example, source 142 may be a boiler. Before being directed through nozzle 120 to form spray 122, the liquid from source 140 and the gas from source 142 may be carried to arm 110 and its interior via pipes 144, 146.

[0035] Along the rotation direction of platform 24, the arm 110b of heating system 104 can be positioned between the arm 110 of cooling system 102 and the bearing head 70. Along the rotation direction of platform 24, the source 140 of heating system 104 can be positioned between the arm 110a of cooling system 102 and the slurry distribution arm 43. For example, the arm 110a of cooling system 102, the arm 110b of heating system 104, the slurry distribution arm 43, and the bearing head 70 can be positioned in this order along the rotation direction of platform 24.

[0036] Instead of separate arms, the temperature control system 100 may include a single arm to distribute both coolant and heating fluid.

[0037] Other techniques may be used alternatively or additionally by the temperature control system 100 to control the temperature of the polishing process. For example, a heated or cooled fluid (e.g., steam or cold water) may be injected into the polishing liquid 42 (e.g., slurry) to raise or lower the temperature of the polishing liquid 42 before it is dispensed. As another example, a resistance heater may be supported in the platform 24 to heat the polishing pad 30, and / or in the carrier head 70 to heat the substrate 10.

[0038] Adjusting the temperature of the slurry and polishing pad during layer polishing allows for increased interaction between charge-bearing abrasive materials, such as cerium oxide. By using temperature control, material removal rates can be beneficially increased by both adjusting the physical parameters of the polishing pad and altering the chemical interaction characteristics between charged cerium dioxide and the filler layer.

[0039] In some implementations, controller 90 receives a signal from temperature sensor 80 and executes a closed-loop control algorithm to control temperature control system 100 (e.g., flow rate, mixing ratio, pressure, or relative temperature of coolant or heating fluid) to maintain the polishing process at a desired temperature.

[0040] In some implementations, the in-situ monitoring system measures the polishing rate of the substrate, and the controller 90 executes a closed-loop control algorithm to control the temperature control system (e.g., flow rate, or relative temperature of the coolant or heating fluid) to maintain the polishing rate at a desired rate.

[0041] Polishing system 20 may also include a high-pressure rinsing system 106. The high-pressure rinsing system 106 includes multiple nozzles 150, for example, three to twenty nozzles, that direct cleaning fluid (e.g., water) at high intensity onto the polishing pad 30 to clean the pad 30 and remove used slurry, polishing debris, etc. The cleaning fluid may flow from a source 156 (e.g., a reservoir of deionized water) through a pipe 152 to the nozzles 150.

[0042] Example rinsing system 106 includes an arm 110c extending over platform 24 and polishing pad 30. Along the rotational direction of platform 24, arm 110c of rinsing system 106 is located between arm 110z of cooling system 102 and arm 110b of heating system 104.

[0043] In some embodiments, the polishing system 20 includes a squeegee 170 (or body) for evenly distributing polishing liquid 42 across the polishing pad 30. The squeegee 170 is positioned between the supply port 40 and the carrier head 70 along the direction of rotation of the platform 24.

[0044] although Figure 2 Separate arms are shown for each subsystem (e.g., cooling system 102, heating system 104, and flushing system 106), but various subsystems may be included in a single assembly supported by a common arm. Various fluid transfer components (e.g., pipes, channels, etc.) may extend inside each body.

[0045] Figure 3 , Figure 4A and Figure 4BA fluid transport line 200 suitable for use in a chemical mechanical polishing system is shown. The fluid transport line 200 can be used for one or more of the following: a fluid transport line 46 for polishing liquids, a pneumatic line 59 for a carrying head, a fluid transport line 96 for an adjusting head, pipes 134, 136 for a cooling system, pipes 144, 146 for a heating system, pipe 152 for a high-pressure rinsing system, and pipes for carrying pneumatic and / or cleaning fluids to a loading hood and / or adjusting a cleaner hood, for example, carrying liquid water or vapor to a cleaner.

[0046] Fluid transfer line 200 may be particularly well-suited for carrying hot gases (e.g., steam) because the combination of steam and temperature can lead to the establishment of electrostatic charges, which may not occur in gases or liquids at room temperature. For example, fluid transfer line 200 may be used as pipe 146 for transferring hot gases (e.g., steam) from source 142 (e.g., boiler), or as pipe for transferring steam for use in cleaning load hoods and / or regulating heads in cleaner hoods.

[0047] The fluid transport line 200 includes a polymer tube 210 wound with a conductive layer 220. The polymer tube can be made of a material that is electrically insulating, withstands temperatures up to 100°C, is inert to the fluid flowing through the fluid transport line 200, and is inert to polishing processes. For example, the polymer tube can be a perfluoroalkoxyalkane (PFA). The polymer tube 210 has an internal channel 212 through which fluid flows.

[0048] A conductive layer 220 is wound around the polymer tube 210 along the length of the fluid transport line 200. The conductive layer 220 may be a continuous layer or a wire mesh. The conductive layer 220 may be a conductive metal, such as copper. Alternatively or additionally, the conductive layer 220 may be carbon in a conductive or semi-conductive form, such as electro-conductive carbon black. Semi-conductive polymer tape or carbon-coated tape may also be used as the conductive layer 220. The conductive layer may be a high-resistance conductive tape, for example, up to 20,000 ohms for a 10' length. In contrast, a carbon sleeve may have significantly lower resistance, for example, 20 ohms for a 10' length. Alternatively, the conductive layer 220 may be formed by applying a conductive varnish (e.g., graphene varnish) to the polymer tube 210.

[0049] The conductive layer at the end of the fluid transport line 200 can be flared. This avoids the formation of sharp points at the end of the fluid transport line, which reduces the risk of electrostatic discharge.

[0050] Facing the ends of the tube, conductive wires 240 are attached to the conductive layer 220 at both ends. These conductive wires 240 can be connected to a common ground. The conductive wires 240 can be stainless steel grounding wires. In some embodiments, portions of the conductive wires are placed between the conductive layer 220 and the polymer tube 210. For example, the conductive wires 240 can be placed against the polymer tube 210 and then secured in place by wrapping conductive tape around the polymer tube 210 and the conductive wires 240.

[0051] Once the conductive layer 220 has been wound around the polymer tube 210, a sheath 230 of another electrically insulating polymer is positioned to directly contact and cover the conductive layer 220. Specifically, a heat-shrinkable material (e.g., PVDF, PTFE, or another material) is applied to the conductive layer 220. For example, an assembly with a polymer tube having the conductive layer 220 can be inserted to extend through the heat-shrinkable tube. The heat-shrinkable tube is then heat-treated to compress the material and bring it into close contact with the conductive layer 220.

[0052] Alternatively, an additional layer of insulating material (such as EPDM, PTFE, PFA) may be wrapped around the heat-shrinkable layer for thermal insulation.

[0053] This fluid transport line provides a grounding path for accumulated charge, thus reducing the risk of component damage while remaining compatible with polishing processes. Furthermore, the heat-shrink tubing protects the outside of the fluid transport line from splashes of liquids from the environment, preventing defects and contamination.

[0054] Several embodiments of the present invention have been described. However, it should be understood that various modifications can be made without departing from the spirit and scope of the invention. Therefore, other embodiments are within the scope of the following claims.

Claims

1. A chemical mechanical polishing assembly, comprising: A chemical mechanical polishing system includes a platform for supporting a polishing pad, a support head for supporting a substrate and bringing the substrate into contact with the polishing pad, and a motor for causing relative movement between the platform and the support head; Fluid source; as well as Fluid transport conduit for carrying fluid from the fluid source to the chemical mechanical polishing system, the fluid transport conduit comprising: Electrical insulation tube; A conductive winding is wound around the outer diameter of the tube from a first end to a second end of the tube, the conductive winding being configured to allow electrostatic discharge to flow. A conductive wire is attached to a first end of the conductive winding, and the conductive wire is configured to allow the electrostatic discharge to flow from the conductive winding to a ground source. A heat shrinkable tube, the heat shrinkable tube surrounding the electrical insulating tube and the conductive winding; as well as An insulating layer surrounds the electrical insulating tube, the conductive winding, and the heat shrinkable tube.

2. The component of claim 1, wherein the fluid source includes a reservoir for holding polishing fluid, the system includes a distributor for transferring the polishing fluid to the polishing pad, and the fluid transfer conduit couples the reservoir to the distributor.

3. The component of claim 1, wherein the fluid source includes a source of cleaning fluid, the system includes a dispenser, an adjustment head, or the carrier head for delivering the cleaning fluid to the polishing pad, and the fluid delivery conduit couples the fluid source to the dispenser.

4. The component of claim 3, wherein the fluid source includes a boiler for generating steam.

5. The component of claim 1, wherein the fluid source includes a source of temperature-controlled fluid, the system includes a distributor for delivering the temperature-controlled fluid to the polishing pad, and the fluid delivery conduit couples the fluid source to the distributor.

6. The component of claim 5, wherein the fluid source includes a boiler for generating steam.

7. The component of claim 1, wherein the fluid source includes a pressure line, wherein the bearing head includes one or more pressurizable chambers, and the fluid transfer conduit couples the pressure line to the bearing head.

8. The component of claim 1, wherein the fluid source includes a pressure line, wherein the system includes an adjustment head that includes one or more pressurizable chambers, and the fluid delivery conduit couples the pressure line to the adjustment head.

9. The component of claim 1, comprising a ground wire coupled to the conductive layer.

10. A fluid conduit, comprising: An electrically insulating tube configured to allow fluid to flow into a chemical mechanical polishing system; A conductive winding, the conductive winding being wound around the outer diameter of the tube from a first end to a second end of the tube, the conductive winding being configured to conduct electrostatic charge; A conductive wire attached to the conductive winding, the conductive wire being configured to conduct the electrostatic charge from the conductive winding to a common ground source; A heat shrinkable tube, the heat shrinkable tube surrounding the electrical insulating tube and the conductive winding; as well as An insulating layer surrounds the electrical insulating tube, the conductive winding, and the heat shrinkable tube.

11. The fluid conduit of claim 10, wherein the conductive winding is a metal wire.

12. The fluid conduit of claim 11, wherein the metal wire is a metal mesh.

13. The fluid conduit of claim 10, wherein the conductive winding is a conductive or semi-conductive polymer tape.

14. A method for manufacturing a fluid conduit, the method comprising: A conductive winding is wound around an electrically insulating tube, which is configured to allow fluid to flow into a chemical mechanical polishing assembly; Conductive wires are coupled to the conductive winding, which is configured to form an electrostatic discharge protection assembly for conducting electrostatic charges; A heat-shrinkable tube is provided surrounding the electrical insulating tube and the conductive winding; as well as An insulating layer is provided surrounding the electrical insulating tube, the conductive winding, and the heat shrinkable tube.

15. The method of claim 14, further comprising: The electrostatic discharge protection component is installed on the chemical mechanical polishing assembly.

16. The method of claim 15, wherein installing the electrostatic discharge protection assembly further comprises: The electrostatic discharge protection component is fluidly coupled from a fluid source to flow fluid from the fluid source to the chemical mechanical polishing component.

17. The method of claim 15, wherein installing the electrostatic discharge protection assembly further comprises: The conductive wire is coupled to a common ground source.

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