Patent Application
20230282506
Embodiments relate to the field of semiconductor manufacturing and, in particular, to a semiconductor processing tool with a rotating pedestal.
Rotating pedestals are used in semiconductor manufacturing environments in order to provide tools that enable highly uniform outcomes on the substrate that is being processed in the tool. In existing tools, the rotating pedestal can comprise a electrostatic chucking electrode and a biasing electrode. The biasing electrode may be electrically coupled to a stationary plate with a wireless configuration. For example, the stationary plate may be capacitively coupled to the biasing electrode. As such, any direct electrical coupling across a conductor is omitted, and the biasing electrode is free to rotate with the pedestal.
Additionally, the electrostatic chucking electrode can be powered by current that passes through a bearing assembly of the rotating pedestal. This facilitates providing power to the chucking electrode while rotating the pedestal. For example, power can be drawn from a DC power source and routed to the bearing assembly. Current flows through the bearing assembly and is subsequently routed to the chucking electrodes via chucking power lines disposed within an interior of the shaft below the pedestal.
Embodiments disclosed herein include an electrostatic chuck. In an embodiment, the electrostatic chuck comprises a pedestal with a support surface for supporting a substrate and a second surface opposite from the support surface, and chucking electrode within the pedestal. In an embodiment, a biasing electrode is within the pedestal, and a heating element is within the pedestal. In an embodiment, the electrostatic chuck further comprises a shaft coupled to the second surface of the pedestal, and a rotation assembly coupled to the shaft to rotate the shaft and the pedestal.
Embodiments may further include a semiconductor tool. In an embodiment, the semiconductor tool comprises a chamber, and a first shaft through the chamber, where a baffle between the first shaft and the chamber seals the chamber. In an embodiment, the semiconductor tool further comprises a second shaft within the first shaft, and a pedestal over a first end of the second shaft within the chamber. In an embodiment, the semiconductor tool further comprises a rotation assembly coupled to the second shaft to rotate the second shaft and the pedestal relative to the first shaft.
Embodiments may further include a semiconductor tool that comprises a chamber, and a pedestal within the chamber. In an embodiment, the pedestal comprises a chucking electrode, a bias electrode, and a heating element. In an embodiment, a first shaft is through a bottom of the chamber, and a second shaft is through the bottom of the chamber and within the first shaft. In an embodiment, the pedestal is coupled to the second shaft. In an embodiment, a baffle is between a portion of the first shaft and the chamber to seal the chamber. In an embodiment, a vacuum feedthrough is at an end of the second shaft opposite from the pedestal, and a radio frequency (RF) rotary feedthrough is below the vacuum feedthrough.
Systems described herein include a semiconductor tool that includes a rotatable pedestal. In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments. It will be apparent to one skilled in the art that embodiments may be practiced without these specific details. In other instances, well-known aspects are not described in detail in order to not unnecessarily obscure embodiments. Furthermore, it is to be understood that the various embodiments shown in the accompanying drawings are illustrative representations and are not necessarily drawn to scale.
As noted above, rotating pedestal architectures currently exist in some semiconductor processing tools. However, the powered components within the pedestal are limited. For example, capacitive coupling can be used to power the biasing electrode, and current can pass over bearings in order to power the electrostatic chucking electrodes. However, high current components of the semiconductor processing tool are not compatible with capacitive coupling or passing power over bearings. For example, heating elements (e.g., lamps, resistive heating elements, etc.) require high currents in order to provide the needed heat to the system.
In existing processing tools, the heating elements are stationary with respect to the rotating pedestal. As such, the current provided to the heating elements does not need to pass across a junction between a stationary component and a rotating component. However, in some processing tools it may be desirable to integrate the heating element into the pedestal. For example, in ultra-low vacuum chambers, it may be necessary to move the heating element into the pedestal in order to mitigate the ability of plasma to ignite below the pedestal. Accordingly, the heating elements will rotate with the pedestal and need an electrical connection that can be maintained across a junction between a stationary component and a rotating component.
Existing solutions (e.g., passing the current over a bearing, or capacitively coupling two plates) is not suitable for such high current applications. Accordingly, embodiments disclosed herein include a slip-ring architecture. The slip-ring architecture allows for high currents to be passed between a stationary component and a rotating component. In some embodiments, a plurality of slip-ring structures may be stacked on each other in order to provide power to a plurality of components (e.g., electrostatic chucking electrodes, biasing electrodes, heating elements, etc.). In a particular embodiment, seven or more slip-ring structures may be used.
Referring now to
The chamber 100 is a vacuum chamber which is suitably adapted to maintain sub-atmospheric pressures within a chamber interior volume 120 during substrate processing. The chamber 100 includes a chamber body 106 covered by a lid 104 which encloses a processing volume 119 located in the upper half of chamber interior volume 120. The chamber 100 may also include one or more shields 105 circumscribing various chamber components to prevent unwanted reaction between such components and ionized process material. The chamber body 106 and lid 104 may be made of metal, such as aluminum. The chamber body 106 may be grounded via a coupling to ground 115.
A substrate support 124 is disposed within the chamber interior volume 120 to support and retain a substrate S, such as a semiconductor wafer, for example, or other such substrate as may be electrostatically retained. The substrate support 124 may generally comprise an electrostatic chuck 150 and a hollow support shaft 112 for supporting the electrostatic chuck 150. The hollow support shaft 112 provides a conduit to provide, for example, process gases, fluids, coolants, power, or the like, to the electrostatic chuck 150.
In some embodiments, the hollow support shaft 112 is coupled to a lift mechanism 113 which provides vertical movement of the electrostatic chuck 150 between an upper, processing position (as shown in
The hollow support shaft 112 provides a conduit for coupling a fluid source 142, a gas supply 141, a chucking power supply 140, and RF sources (e.g., RF plasma power supply 170 and RF bias power supply 117) to the electrostatic chuck 150. In some embodiments, RF plasma power supply 170 and RF bias power supply 117 are coupled to the electrostatic chuck via respective RF match networks (only RF match network 116 shown).
A substrate lift 130 may include lift pins 109 mounted on a platform 108 connected to a shaft 111 which is coupled to a second lift mechanism 132 for raising and lowering the substrate lift 130 so that the substrate “S” may be placed on or removed from the electrostatic chuck 150. The electrostatic chuck 150 includes thru-holes to receive the lift pins 109. A bellows assembly 131 is coupled between the substrate lift 130 and bottom surface 126 to provide a flexible seal which maintains the chamber vacuum during vertical motion of the substrate lift 130.
The chamber 100 is coupled to and in fluid communication with a vacuum system 114 which includes a throttle valve (not shown) and vacuum pump (not shown) which are used to exhaust the chamber 100. The pressure inside the chamber 100 may be regulated by adjusting the throttle valve and/or vacuum pump. The chamber 100 is also coupled to and in fluid communication with a process gas supply 118 which may supply one or more process gases to the chamber 100 for processing a substrate disposed therein.
In operation, for example, a plasma 102 may be created in the chamber interior volume 120 to perform one or more processes. The plasma 102 may be created by coupling power from a plasma power source (e.g., RF plasma power supply 170) to a process gas via one or more electrodes proximate to or within the chamber interior volume 120 to ignite the process gas and creating the plasma 102. In some embodiments, a bias power may also be provided from a bias power supply (e.g., RF bias power supply 117) to one or more electrodes (described below) disposed within the electrostatic chuck 150 to attract ions from the plasma towards the substrate S.
In some embodiments, for example where the chamber 100 is a PVD chamber, a target 166 comprising a source material to be deposited on a substrate S may be disposed above the substrate and within the chamber interior volume 120. The target 166 may be supported by a grounded conductive portion of the chamber 100, for example an aluminum adapter through a dielectric isolator. In other embodiments, the chamber 100 may include a plurality of targets in a multi-cathode arrangement for depositing layers of different material using the same chamber.
A controllable DC power source 168 may be coupled to the chamber 100 to apply a negative voltage, or bias, to the target 166. The RF bias power supply 117 may be coupled to the substrate support 124 in order to induce a negative DC bias on the substrate S. In addition, in some embodiments, a negative DC self-bias may form on the substrate S during processing. In some embodiments, an RF plasma power supply 170 may also be coupled to the chamber 100 to apply RF power to the target 166 to facilitate control of the radial distribution of a deposition rate on substrate S. In operation, ions in the plasma 102 created in the chamber 100 react with the source material from the target 166. The reaction causes the target 166 to eject atoms of the source material, which are then directed towards the substrate S, thus depositing material.
Referring now to
An interior volume 220 of the chamber 200 may be configured to be maintained at a sub-atmospheric pressure using throttle valves, vacuum pumps, and the like. Such components are omitted from
In an embodiment, the first shaft 212 may sometimes be referred to as a stationary shaft 212. That is, the first shaft 212 may remain stationary while a second shaft 270 within the first shaft 212 is rotated. The rotation of the second shaft 270 relative to the first shaft 212 may be aided by the presence of one or more bearings 272, 273, and 274 between the first shaft 212 and the second shaft 270. In a particular embodiment, the bearing 274 may be a cross-roller bearing 274. In an embodiment, a region 222 between the exterior of the second shaft 270 and an interior of the first shaft 212 may be held at the sub-atmospheric pressure (which may be referred to as a vacuum pressure). In a particular embodiment, the region 222 may have a pressure less than 10 Tor. For example, the region 222 may have a pressure between approximately 1 Tor and approximately 10 Tor.
In an embodiment, the second shaft 270 may be rotated with any suitable driving architecture. In the particular embodiment shown in
In an embodiment, a plurality of wires 276 may be fed through a vacuum feedthrough 275. While a single wire 276 is shown within the second shaft 270, it is to be appreciated that two or more wires 276 may pass through the vacuum feedthrough 275 and into the second shaft 270. The interior volume 223 of the second shaft 270 may be at atmospheric pressure in some embodiments. In some embodiments, the interior volume 223 may be at a pressure higher than atmospheric pressure. The higher pressure (e.g., at atmospheric pressure or above) prevents breakdown within the interior volume 223.
In an embodiment, the wires 275 may extend out of an RF rotary feedthrough 280. The RF rotary feedthrough 280 may include a stator 281 and a rotor 282. That is, the stator 281 remains stationary (coupled to the outer first shaft 212), and the rotor 282 is free to rotate with the inner second shaft 270. The RF rotary feedthrough 280 may have any number of electrical pathways that allow for propagating power across a junction between a stationary component (i.e., the stator 281) and a rotating component (i.e., the rotor 282). The construction of the RF rotary feedthrough 280 allows for high current to pass across the boundary between rotating and stationary components. As such, one or more of the wires 275 may be used to feed heating elements (not shown) in the pedestal 224. In some instances, the RF rotary feedthrough 280 may have a slip-ring type structure. Contacts 283 may be provided on a bottom of the stator 281. While referred to as an RF rotary feedthrough, it is to be appreciated that other electric current from 0 GHz to 100 GHz may be propagated through the RF rotary feedthrough 280.
Referring now to
Similarly, the stator 381 may comprise a plurality of electrically conductive layers 385. The number of electrically conductive layers 385 may be equal to the number of electrically conductive layers 384 in the rotor 382. The layers 385 may be electrically isolated from each other by insulating layers 387. In an embodiment, the electrically conductive layers 384 may be coupled to a bottom surface of the stator 381 by vias (not shown) through a thickness of the stator 381.
In order to provide connections between the stationary layers 385 and the rotating layers 384, a plurality of conductive connector rings 386 may be provided. For example, copper rings or the like may be secured between ends of the layers 385 and ends of the layers 384. As the center rotor 382 rotates, the connector rings 386 rotate and maintain an electrical connection between the stator 381 and the rotor 382. In the illustrated embodiment, a set of seven connector rings 386 are shown, one for each of the layers 384 and 385. However, it is to be appreciated that the RF rotary feedthrough may include any number of connector rings 386 (e.g., one or more rings 386).
The structure of the connector rings 386 may be more clearly illustrated in
In
Referring now to
As shown in
As shown in
While three wires 495 are shown, it is to be appreciated that any number of wires 495 may be used. The number of wires 495 may match the number of connector rings in the RF rotary feedthrough. In a particular embodiment, seven wires 495 are fed through the inner shaft 470. Four out of the seven wires 495 may be used for the heating element (e.g., to support two zones), a fifth wire 495 may be used for electrostatic chucking electrode 491, a sixth wire 495 may be used to provide RF power to the biasing electrode 492, and a seventh wire 495 may be used to probe the backside of the substrate to determine the center tap for the electrostatic chucking power supply.
Referring now to
Computer system 500 may include a computer program product, or software 522, having a non-transitory machine-readable medium having stored thereon instructions, which may be used to program computer system 500 (or other electronic devices) to perform a process according to embodiments. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., a computer) readable storage medium (e.g., read only memory (“ROM”), random access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory devices, etc.), a machine (e.g., computer) readable transmission medium (electrical, optical, acoustical or other form of propagated signals (e.g., infrared signals, digital signals, etc.)), etc.
In an embodiment, computer system 500 includes a system processor 502, a main memory 504 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), a static memory 506 (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory 518 (e.g., a data storage device), which communicate with each other via a bus 530.
System processor 502 represents one or more general-purpose processing devices such as a microsystem processor, central processing unit, or the like. More particularly, the system processor may be a complex instruction set computing (CISC) microsystem processor, reduced instruction set computing (RISC) microsystem processor, very long instruction word (VLIW) microsystem processor, a system processor implementing other instruction sets, or system processors implementing a combination of instruction sets. System processor 502 may also be one or more special-purpose processing devices such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal system processor (DSP), network system processor, or the like. System processor 502 is configured to execute the processing logic 526 for performing the operations described herein.
The computer system 500 may further include a system network interface device 508 for communicating with other devices or machines. The computer system 500 may also include a video display unit 510 (e.g., a liquid crystal display (LCD), a light emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device 512 (e.g., a keyboard), a cursor control device 514 (e.g., a mouse), and a signal generation device 516 (e.g., a speaker).
The secondary memory 518 may include a machine-accessible storage medium 532 (or more specifically a computer-readable storage medium) on which is stored one or more sets of instructions (e.g., software 522) embodying any one or more of the methodologies or functions described herein. The software 522 may also reside, completely or at least partially, within the main memory 504 and/or within the system processor 502 during execution thereof by the computer system 500, the main memory 504 and the system processor 502 also constituting machine-readable storage media. The software 522 may further be transmitted or received over a network 520 via the system network interface device 508. In an embodiment, the network interface device 508 may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.
While the machine-accessible storage medium 532 is shown in an exemplary embodiment to be a single medium, the term “machine-readable storage medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term “machine-readable storage medium” shall also be taken to include any medium that is capable of storing or encoding a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies. The term “machine-readable storage medium” shall accordingly be taken to include, but not be limited to, solid-state memories, and optical and magnetic media.
In the foregoing specification, specific exemplary embodiments have been described. It will be evident that various modifications may be made thereto without departing from the scope of the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.
