Embodiments relate to the field of semiconductor manufacturing and, in particular, to thermal solutions for high-frequency plasma sources.
The electrical components of a high-frequency plasma system are susceptible to heat. For example, the high-frequency plasma source and cables (e.g., coaxial cables or the like) may be damaged or degraded by the heat generated by the system. Particularly, heat generated by the plasma or heat from a heated chamber may be transferred from the antenna back towards the electrical components that drive the plasma. In some instances the heat generated by the system is sufficient to melt connections between the source of high-frequency power and the antenna.
Embodiments disclosed herein include a high-frequency emission module. In an embodiment, the high-frequency emission module comprises a solid state high-frequency power source, an applicator for propagating high-frequency electromagnetic radiation from the power source, and a thermal break coupled between the power source and the applicator. In an embodiment, the thermal break comprises a substrate, a trace on the substrate, and a ground plane.
Embodiments may also include a processing tool. In an embodiment, the processing tool comprises a processing chamber, and a modular high-frequency emission source. In an embodiment, the modular high-frequency emission source comprises a plurality of high-frequency emission modules. In an embodiment, each high frequency emission module comprises an oscillator module, an amplification module coupled to the oscillator module, a thermal break coupled to the amplification module, and an applicator. In an embodiment, the applicator is coupled to the amplification module by the thermal break, and the applicator is positioned opposing a chuck in the processing chamber on which one or more substrates are processed.
Embodiments may also include a thermal break for a high-frequency plasma source. In an embodiment, the thermal break comprises a substrate having a first surface and a second surface opposite the first surface, where the substrate comprises one or more dielectric layers. In an embodiment, the thermal break further comprises a connector coupled to the substrate, where the connector is configured to receive a coaxial cable, and a conductive trace interfacing with the connector, and where the conductive trace extends from the connector towards an edge of the substrate opposite from the connector. In an embodiment, the thermal break further comprises a ground plane embedded in the substrate, where the ground plane is not electrically coupled to the conductive trace, and a thermal solution thermally coupled to the substrate.
Systems and methods described herein include thermal solutions for high-frequency plasma sources. 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, plasma processing tools that utilize high-frequency plasma sources are susceptible to degradation or damage resulting from heat transfer from the plasma and/or the chamber to the power source and the cabling between the power source and the antenna. In some instances, it has even been observed that the thermal load causes the cabling to melt. Accordingly, embodiments disclosed herein include a thermal break that thermally isolates the cabling and the solid state electronics of the power source from the thermal load supplied by a plasma and/or the chamber.
In some embodiments, the thermal break is located between the applicator (e.g., an antenna) and solid state electronics of the processing tool. For example, the solid state electronics may be electrically coupled to the thermal break by a coaxial cable, and the thermal break may be directly coupled to the antenna. In addition to providing thermal isolation between components of the processing tool, the thermal break also provides an electrical coupling from the coaxial cable to the antenna. In some embodiments, the thermal break may also function as an impedance matching element in order to allow for efficient transfer of power to the plasma. Accordingly, the impedance matching and the thermal regulation may be implemented in a single component (i.e., the thermal break). This reduces the complexity and provides for a compact construction.
Referring now to
The solid state power source 105 may comprise a plurality of sub-components, such as an oscillator, amplifiers, and other circuitry blocks. A more detailed description of the solid state power source 105 is provided below with respect to
In an embodiment, the applicator 142 may comprise a dielectric body 144 with a cavity into which an antenna 143 is disposed. For example, the antenna 143 may comprise a conductive line (e.g., a monopole) that extends into the dielectric body 144. In some embodiments, the antenna 143 is in direct contact with the dielectric body 144. In other embodiments, the cavity is larger than the antenna 143, and the antenna 143 is spaced away from surfaces of the dielectric body 144.
In an embodiment, the applicator 142 may be electrically coupled to the thermal break 150. The thermal break 150 may comprise a substrate 152 and a conductive trace 151. In an embodiment, the substrate 152 may be a printed circuit board (PCB) or the like. That is, the substrate 152 may comprise one or more dielectric layers. In the illustrated embodiment, the trace 151 is shown as being above the substrate 152. In a particular embodiment, the conductive trace 151 may be a microstrip. However, it is to be appreciated that the trace 151 may be embedded within the substrate 152 in some embodiments. In a particular embodiment, the conductive trace 151 may be a stripline. That is, a ground plane (not shown in
In an embodiment, the thermal break 150 may also comprise a thermal solution. The thermal solution may provide thermal regulation to the high-frequency emission module 103. Since the thermal break 150 is located between the applicator 142 and the solid state power source 105, thermal energy (e.g., from the plasma or a heated chamber) is dissipated prior to reaching the solid state power source 105.
Furthermore, cabling and connectors (e.g., a coaxial cable 155 and connectors 153) between the thermal break 150 and the solid state power source 105 is protected from thermal energy dissipated by the system. In an embodiment, the coaxial cable 155 may be electrically coupled between the solid state power source 105 and the thermal break 150 with connectors 153, as is known in the art. For example, a connector 153 may electrically couple the coaxial cable 155 to the conductive trace 151.
Referring now to
Referring now to
In an embodiment, one or more channels 257 may be embedded in the thermal block 256. The channels 256 may be suitable for flowing a coolant through the thermal block 256 in order to remove heat from the system. As shown, a single inlet (IN) and a single outlet (OUT) are shown. However, it is to be appreciated that the thermal block 256 may comprise any number of inlets and outlets.
In an embodiment, the coolant may comprise any suitable coolant fluid. For example, the coolant fluid may comprise a liquid (e.g., a water-glycol mixture) or a gas (e.g., air, helium, etc.). The coolant fluid may be stored in a reservoir. The reservoir may be actively cooled in order to improve the heat extraction from the thermal break 250.
Referring now to
Referring now to
In addition to providing thermal dissipation from the system, embodiments may also include a thermal break that has a dual functionality. Particularly, the thermal break may also provide impedance matching to the system. By controlling the shape of the conductive trace, the impedance matching of the system may be modulated. Examples of various shaped traces 351 that may be used to providing impedance matching are shown in
Referring now to
In an embodiment, the trace 351 may have a substantially uniform width W and extend linearly across the substrate 352. That is, the trace 351 may have a substantially rectangular shape. In other embodiments, the trace 351 may have a non-linear path across the substrate 352. For example, the trace 351 may include a serpentine pattern in order to increase the length of the trace 351. In other embodiments, the trace 351 may have a first width at the first edge 361 and a second width at the second edge 362. In an embodiment, a width W of the trace 351 may be substantially uniform (e.g., the first width and the second width are substantially the same), or the width of the trace 351 may be a substantially non-uniform width W across a length of the trace (e.g., a width of the trace 351 proximate to the first edge 361 may be different than a width of the trace 351 proximate to the second edge 362). In an embodiment, the trace 351 may have a rectangular cross-section (i.e., the cross-section in the X-Z plane may be rectangular). In other embodiments, the trace 351 may have a non-rectangular cross-section in the X-Z plane. For example, the cross-section of the trace 351 in the X-Z plane may be trapezoidal. In other embodiments, the trace 351 may comprise a first trace and a second trace directly over the first trace. The first trace and the second trace may have different widths. For example, the first trace may have a width that is greater than a width of the second trace, or the first trace may have a width that is less than a width of the second trace.
Referring now to
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In an embodiment, the modular high-frequency emission source 404 may inject high-frequency electromagnetic radiation into a chamber 478 through a dielectric window 475. The high-frequency electromagnetic radiation may induce a plasma 490 in the chamber 478. The plasma 490 may be used to process a substrate 474 that is positioned on a support 476 (e.g., an electrostatic chuck (ESC) or the like).
Referring now to
According to an embodiment, the electromagnetic radiation is transmitted from the voltage controlled oscillator 520 to an amplification module 530. The amplification module 530 may include a driver/pre-amplifier 534, and a main power amplifier 536 that are each coupled to a power supply 539. According to an embodiment, the amplification module 530 may operate in a pulse mode. For example, the amplification module 530 may have a duty cycle between 1% and 99%. In a more particular embodiment, the amplification module 530 may have a duty cycle between approximately 15% and 50%.
In an embodiment, the electromagnetic radiation may be transmitted to the thermal break 550 and the applicator 542 after being processed by the amplification module 530. However, part of the power transmitted to the thermal break 550 may be reflected back due to the mismatch in the output impedance. Accordingly, some embodiments include a detector module 581 that allows for the level of forward power 583 and reflected power 582 to be sensed and fed back to the control circuit module 521. It is to be appreciated that the detector module 581 may be located at one or more different locations in the system. In an embodiment, the control circuit module 521 interprets the forward power 583 and the reflected power 582, and determines the level for the control signal 585 that is communicatively coupled to the oscillator module 506 and the level for the control signal 586 that is communicatively coupled to the amplifier module 530. In an embodiment, control signal 585 adjusts the oscillator module 506 to optimize the high-frequency radiation coupled to the amplification module 530. In an embodiment, control signal 586 adjusts the amplifier module 530 to optimize the output power coupled to the applicator 542 through the thermal break 550. In an embodiment, the feedback control of the oscillator module 506 and the amplification module 530, in addition to the tailoring of the impedance matching in the thermal break 550 may allow for the level of the reflected power to be less than approximately 5% of the forward power. In some embodiments, the feedback control of the oscillator module 506 and the amplification module 530 may allow for the level of the reflected power to be less than approximately 2% of the forward power.
Accordingly, embodiments allow for an increased percentage of the forward power to be coupled into the processing chamber 578, and increases the available power coupled to the plasma. Furthermore, impedance tuning using a feedback control is superior to impedance tuning in typical slot-plate antennas. In slot-plate antennas, the impedance tuning involves moving two dielectric slugs formed in the applicator. This involves mechanical motion of two separate components in the applicator, which increases the complexity of the applicator. Furthermore, the mechanical motion may not be as precise as the change in frequency that may be provided by a voltage controlled oscillator 520.
Referring now to
In
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According to an embodiment, every applicator 642 may be paired with a different sensor 690. In such embodiments, the output from each sensor 690 may be used to provide feedback control for the respective applicator 642 to which the sensor 690 has been paired. Additional embodiments may include pairing each sensor 690 with a plurality of applicators 642. For example, each sensor 690 may provide feedback control for multiple applicators 642 to which the sensor 690 is proximately located. In yet another embodiment, feedback from the plurality of sensors 690 may be used as a part of a multi-input multi-output (MIMO) control system. In such an embodiment, each applicator 642 may be adjusted based on feedback from multiple sensors 690. For example, a first sensor 690 that is a direct neighbor to a first applicator 642 may be weighted to provide a control effort to the first applicator 642 that is greater than the control effort exerted on the first applicator 642 by a second sensor 690 that is located further from the first applicator 642 than the first sensor 690.
Referring now to
Referring now to
Computer system 760 may include a computer program product, or software 722, having a non-transitory machine-readable medium having stored thereon instructions, which may be used to program computer system 760 (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 760 includes a system processor 702, a main memory 704 (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 706 (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory 718 (e.g., a data storage device), which communicate with each other via a bus 730.
System processor 702 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 702 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 702 is configured to execute the processing logic 726 for performing the operations described herein.
The computer system 760 may further include a system network interface device 708 for communicating with other devices or machines. The computer system 760 may also include a video display unit 710 (e.g., a liquid crystal display (LCD), a light emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device 712 (e.g., a keyboard), a cursor control device 714 (e.g., a mouse), and a signal generation device 716 (e.g., a speaker).
The secondary memory 718 may include a machine-accessible storage medium 731 (or more specifically a computer-readable storage medium) on which is stored one or more sets of instructions (e.g., software 722) embodying any one or more of the methodologies or functions described herein. The software 722 may also reside, completely or at least partially, within the main memory 704 and/or within the system processor 702 during execution thereof by the computer system 760, the main memory 704 and the system processor 702 also constituting machine-readable storage media. The software 722 may further be transmitted or received over a network 720 via the system network interface device 708. In an embodiment, the network interface device 708 may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.
While the machine-accessible storage medium 731 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.
This application claims the benefit of U.S. Provisional Application No. 62/837,922, filed on Apr. 24, 2019, the entire contents of which are hereby incorporated by reference herein.
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