RF Power Path Symmetry

Abstract

In some examples, a multi-station process tool includes a plurality of process chambers, each process chamber located at a station of the multi-station process tool, and RF power path components associated with each station of the multi-station process tool, the RF power path components positioned and oriented such that, when energized, a symmetric RF power path is formed about a center of the multi-station process tool.

Description

[Technical field]

[0001] [Priority claim] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 305,606, filed February 1, 2022, which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to systems and methods for RF power path symmetry and configuration, and in some examples, geometric configuration of components for symmetric RF power paths and gas flow symmetry in multi-station process modules in semiconductor manufacturing applications. [Background technology]

[0003] Conventional multi-station substrate processing chambers employing powered pedestals typically use various component configurations to deliver RF power. Conventional RF power path configurations are typically constrained by what components can be mounted adjacent to or within the external chamber hardware. The geometric configurations of the RF power components can vary with excessive or unacceptable tolerance levels and / or be asymmetrical relative to the substrate processing stations.

[0004] The external chamber hardware may include process gas exhaust lines, valve components, and several filters and enclosures for RF matching circuits. Conventional configurations of exhaust lines may make it difficult to access the lower chamber hardware, for example. The lower portion of some process stations may be crowded, making it difficult to add or configure new hardware and RF power components. In particular, some lower chamber hardware is particularly difficult to work with due to the orientation of the pedestal lift, which is dictated by the shape and location of the gas lines. Conventional configurations of external chamber hardware may significantly impede the creation of a common geometry of RF power components and the establishment of symmetrical RF power paths.

[0005] The background description provided herein is intended to provide a general overview of the contents of the present disclosure. Work by the currently named inventors within the scope of what is described in this background section, as well as aspects of the description that may not otherwise be regarded as prior art at the time of filing, are not admitted, expressly or impliedly, as prior art against the present disclosure. Summary of the Invention

[0006] In some examples, a multi-station process tool includes a plurality of process chambers, each process chamber located at a station of the multi-station process tool, and RF power path components associated with each station of the multi-station process tool, the RF power path components positioned and oriented such that, when energized, an RF power path is formed that is symmetrical with respect to an axis of symmetry of the multi-station process tool.

[0007] In some examples, the axis of symmetry is located at a center of the multi-station process tool. In some examples, the center of the multi-station process tool is defined by an axis of a spindle motor of the multi-station process tool.

[0008] In some examples, the RF power path components include an RF component enclosure.

[0009] In some examples, the multi-station process tool of claim 1 includes a quad-station process module (QSM) having four stations, each station including a process chamber.

[0010] In some examples, the geometric position and orientation of the first RF power path component relative to a first of the four stations of the QSM is symmetrical to the geometric position and orientation of the second RF power path component relative to a second of the four stations of the QSM.

[0011] In some examples, the geometric position and orientation of the first non-RF component relative to the first station is symmetrical to the geometric position and orientation of the second non-RF component relative to the second station of the QSM.

[0012] In some examples, asymmetries in RF power path components or non-RF components are common to each station of a multi-station process tool.

[0013] In some examples, the multi-station process tool includes a foreline assembly including four inlets, each connectable to a chamber port of a station of the QSM; an outlet connectable directly or indirectly to a vacuum source; a first foreline branch located proximate to the outlet of the foreline assembly; two second foreline branches, each located between the first foreline branch and a respective pair of the four inlets; and first and second foreline branches dividing the foreline assembly into three sections: a first section extending from the four inlets to the two second foreline branches, a second section extending from the two second foreline branches to the first foreline branch, and a third section extending from the first branch to the outlet of the foreline assembly.

[0014] In some examples, the respective diameters of the forelines within each section increase stepwise at each branch in the direction of gas flow from at least one of the four inlets to the outlet of the foreline assembly and are constant within each section of the foreline assembly.

[0015] In some examples, the diameter of the foreline in the first section ranges from about 1.5 inches to about 2.5 inches, the diameter of the foreline in the second section ranges from about 2.5 inches to about 3.5 inches, and the diameter of the foreline in the third section ranges from about 3.5 inches to about 4.5 inches.

[0016] In some examples, the diameter of the foreline in the first section is about 2 inches, the diameter of the foreline in the second section is about 3 inches, and the diameter of the foreline in the third section is about 4 inches.

[0017] In some examples, the multi-station process tool further comprises a T-piece connector provided on each of the two second branches.

[0018] In some examples, the T-piece connector includes an outwardly converging conical section that transitions the diameter of the foreline in the first section to the diameter of the foreline in the second section.

[0019] In some examples, the separation distance between the T-piece connector and the underside of the QSM is configured to accommodate RF power path components between the T-piece connector and the underside of the QSM. [Brief description of the drawings]

[0020] Some embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.

[0021] [Figure 1] FIG. 1 illustrates a schematic diagram of a substrate processing tool in which the exemplary RF power path symmetry and gas flow symmetry of the present disclosure may be deployed. [Diagram 2] FIG. 2 illustrates a schematic diagram of a substrate processing tool in which the exemplary RF power path symmetry and gas flow symmetry of the present disclosure may be deployed. [Diagram 3] FIG. 3 illustrates a schematic diagram of a substrate processing tool in which the exemplary RF power path symmetry and gas flow symmetry of the present disclosure may be deployed. [Figure 4] FIG. 4 illustrates a schematic diagram of a substrate processing tool in which the exemplary RF power path symmetry and gas flow symmetry of the present disclosure may be deployed.

[0022] [Diagram 5] FIG. 5 is a schematic diagram of an example substrate processing tool including a quad station process module in which the example RF power path symmetry and gas flow symmetry of the present disclosure may be deployed.

[0023] [Figure 6] FIG. 6 illustrates an exemplary configuration of RF power path components and a foreline assembly mounted to a QSM, according to an exemplary embodiment. [Figure 7] FIG. 7 illustrates an exemplary configuration of RF power path components and a foreline assembly mounted to a QSM, according to an exemplary embodiment. [Figure 8] FIG. 8 illustrates an exemplary configuration of RF power path components and a foreline assembly mounted to a QSM, according to an exemplary embodiment.

[0024] [Figure 9] FIG. 9 illustrates a pictorial view of a foreline assembly (not attached to the QSM for clarity) in accordance with an illustrative embodiment. [Figure 10] FIG. 10 illustrates a pictorial view of a foreline assembly (not attached to a QSM for clarity) in accordance with an illustrative embodiment.

[0025] [Figure 11] FIG. 11 illustrates a pictorial diagram of a spool piece in accordance with an exemplary embodiment.

[0026] [Figure 12]FIG. 12 is a flowchart illustrating operations in a method according to an exemplary embodiment.

[0027] [Figure 13] FIG. 13 illustrates an embodiment of a semiconductor manufacturing process, according to an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The following description includes systems, methods, techniques, instruction sequences, and computing machine program products embodying exemplary embodiments of the present disclosure. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments. However, it will be apparent to one skilled in the art that the present disclosure may be practiced without these specific details.

[0029] Portions of the disclosure of this patent document may contain material that is subject to copyright protection. The copyright owner has no objection to the patent document or patent disclosure being reproduced by anyone solely as such, as such patent document or patent disclosure appears in the Patent and Trademark Office patent file file or records, but otherwise reserves all copyrights. The following notice applies to all data hereinafter described or illustrated and forming a part of this document:Copyright Lam Research Corporation,2019-2021,All Rights Reserved.

[0030] Substrate processing systems may be used to perform deposition, etching, and / or other processing of substrates, such as semiconductor wafers. During processing, the substrate is placed on a substrate support in a processing chamber of the substrate processing system. During etching or deposition, a gas mixture containing one or more etching gases or gas precursors, respectively, may be introduced into the processing chamber and a plasma may be ignited using RF power to activate a chemical reaction.

[0031] The substrate processing system may include multiple substrate processing tools arranged in a fabrication chamber. Each of the substrate processing tools may include multiple process modules. Typically, a substrate processing tool includes up to six process modules.

[0032] Referring now to FIG. 1, a top view of an exemplary substrate processing tool 100 is shown. The substrate processing tool 100 includes multiple process modules 104. In some examples, each of the process modules 104 may be configured to perform one or more respective processes on a substrate. A substrate to be processed is loaded into the substrate processing tool 100 via a port of a loading station of an equipment front-end module (EFEM) 108 and then transferred to one or more of the process modules 104. For example, a substrate may be loaded into each of the process modules 104 sequentially. The process modules 104 may be or include a multi-station process module, such as a quad-station process module (QSM) described below. Referring now to FIG. 2, an exemplary arrangement 200 of a fabrication chamber 204 including multiple substrate processing tools 208 is shown.

[0033] 3 illustrates a first exemplary configuration 300 including a first substrate processing tool 304 and a second substrate processing tool 308. Each of the processing tools 304 and 308 may include one or more processing modules 104 or QSMs. The first substrate processing tool 304 and the second substrate processing tool 308 are connected by a transfer stage 312 that is sequentially arranged and under vacuum. As illustrated, the transfer stage 312 includes a pivoting transfer mechanism configured to transfer substrates between a vacuum transfer module (VTM) 316 of the first substrate processing tool 304 and a vacuum transfer module (VTM) 320 of the second substrate processing tool 308. However, in other examples, the transfer stage 312 may include other suitable transfer mechanisms, such as a linear transfer mechanism. In some examples, a first robot (not shown) of the VTM 316 may place a substrate on supports 324 located at a first position, the supports 324 are pivoted to a second position, and a second robot (not shown) of the VTM 320 retrieves the substrate from the supports 324 at the second position. In some examples, the second substrate processing tool 308 may include a storage buffer 328 configured to store one or more substrates between processing stages.

[0034] The transfer mechanisms may also be stacked to provide more than one transfer system between the substrate processing tools 308 and 304. The transfer stage 312 may also have multiple slots for carrying or buffering multiple substrates at one time.

[0035] In the configuration 300 , the first substrate processing tool 304 and the second substrate processing tool 308 are configured to share a single front end equipment module (EFEM) 332 .

[0036] 4 illustrates a second exemplary configuration 400 including a first substrate processing tool 404 and a second substrate processing tool 408 arranged sequentially and connected by a transfer stage 412. Configuration 400 is similar to configuration 300 of FIG. 3, except that in configuration 400, EFEM 332 is eliminated. Thus, a substrate may be loaded into the first substrate processing tool 404 directly (e.g., using a storage or transfer carrier such as a vacuum wafer carrier, a Front Opening Unified Pod (FOUP), an atmospheric (ATM) robot, or other suitable mechanism) via an airlock loading station 416.

[0037] Examples of the present disclosure may be deployed in a multi-station process module or process chamber, such as a QSM. In some examples, as shown in FIG. 5, a substrate processing tool 500 includes four QSMs 508 located at each corner of the substrate processing tool 500. Other arrangements of process modules 508 are possible. Each QSM 508 has four stations 518. The substrate processing tool 500 includes transfer robots 502 and 504, collectively referred to as transfer robots 502 / 504. The processing tool 500 is shown without a mechanical indexer for illustrative purposes. In other examples, each process module 508 of the tool 500 may include a mechanical indexer.

[0038] Each of the VTM 516 and the EFEM 510 may include one of the transfer robots 502 / 504. The transfer robots 502 / 504 may have the same or different configurations. In some examples, the transfer robot 502 is shown as having two arms, each having two vertically stacked end effectors. The robot 502 of the VTM 516 selectively transfers substrates to and from the EFEM 510 and between the process modules 508. The robot 504 of the EFEM 510 transfers substrates to and from the EFEM 510. In some examples, the robot 504 may have two arms, each having a single end effector or two vertically stacked end effectors. The system controller 506 may control various operations of the example substrate processing tool 500 and its components, including, but not limited to, the operation of the robots 502 / 504 and the rotation of the indexers of each of the process modules 508.

[0039] The tool 500 is configured to couple with, for example, each of four QSMs 508. Each QSM 508 may have a single load station accessible via a respective slot 512. Other arrangements are possible. In the illustrated approach, two QSMs 508, each having a single load station, are coupled to a side 514 of the VTM 516. The EFEM 510 may be disposed at least partially between the two process modules 508.

[0040] During substrate processing in the QSM 508, process gases enter the module, for example, to assist in the generation of a plasma. The gases then exit the process module 508. The discharge of exhaust gases may be performed by a vacuum or exhaust line, also referred to herein as a foreline or foreline assembly. One or more forelines in a foreline assembly may be located below each QSM 508 in the processing tool 500 and may be connected to a vacuum source to discharge gases from the QSM 508. Each foreline of the foreline assembly may serve to exhaust gases from a respective station 518 of the QSM 508.

[0041] FIG. 6 shows an overview of an exemplary configuration of the QSM 600. Some QSM 600 components have been omitted for clarity. The QSM 600 includes four stations 608 arranged in a generally square configuration at each corner of the QSM 600. Other arrangements of the stations 608 are possible. Each station includes a vacuum chamber for processing a substrate using RF power and plasma gas flow as described in more detail below. Each station 608 in the QSM 600 includes a wafer support 610 that supports a substrate (also generally, but not limited to, referred to herein as a wafer) during processing. In some examples, the wafer support 610 includes a pedestal or electrostatic chuck (ESC) that is powered by an RF power path. Other types of wafer supports or components may be used to support wafers in the stations 608 and perform different types of processes on them.

[0042] Each station 608 includes a respective lift pin actuator assembly 612 that can move the lift pins upward to disengage the wafer during wafer transfer. The QSM 600 includes a spindle 602 that can transfer a wafer from one wafer support 610 to another. The spindle 602 can be driven by a spindle motor 704, which can be seen more clearly in FIG. 7. For clarity, a transfer plate on which the spindle 602 can act is not depicted in the figure. The transfer plate can rotate during the wafer transfer phase, and the movement of the wafer during this phase can be coordinated with the movement of the wafer provided by other wafer transfer mechanisms, such as the transfer robot 502 / 504 of FIG. 5.

[0043] For purposes of illustration, FIG. 13 shows aspects of an exemplary semiconductor manufacturing process that may be performed in station 608 of a processing tool such as QSM 600. FIG. 13 illustrates a vacuum chamber 1300. According to some examples, the vacuum chamber may be an etch chamber or a deposition chamber for manufacturing substrates. Exciting an electric field between two electrodes in an RF power path is one way to obtain a radio frequency (RF) gas discharge in the vacuum chamber. When an oscillating voltage is applied between the electrodes, the resulting discharge is called a CCP discharge.

[0044] A plasma 1302 may be generated in the processing zone 1330 of the vacuum chamber 1300 utilizing one or more process gases to produce a wide variety of chemically reactive by-products generated by dissociation of various molecules caused by electron-neutral collisions. The chemical aspect of etching involves the reaction of neutral gas molecules and their dissociated by-products with molecules on the surface being etched to produce volatile molecules. The volatile molecules may be pumped away. When the plasma is generated, positive ions are accelerated out of the plasma, cross a space charge sheath that separates the plasma from the chamber walls, and impact the substrate surface with sufficient energy to remove material from the substrate surface. The process of selectively and anisotropically removing material from a substrate surface using energetic and chemically reactive ions is called reactive ion etching (RIE). In some examples, the vacuum chamber 1300 may be used in conjunction with a PECVD or PEALD deposition process.

[0045] A controller 1316 manages the operation of the vacuum chamber 1300 through control of various elements within the chamber, such as an RF generator 1318, a gas source 1322, and a gas pump 1320. In one embodiment, fluorocarbon gases, such as CF4 and C4F8, are used in the dielectric etch process for their anisotropic and selective etching capabilities; however, the principles described herein are applicable to other plasma generating gases. Fluorocarbon gases readily dissociate into chemically reactive by-products, including smaller molecular and atomic radicals. These chemically reactive by-products etch away the dielectric material.

[0046] The vacuum chamber 1300 illustrates a processing chamber with an upper (top) electrode 1304 and a lower (bottom) electrode 1308 in the RF power path. The upper electrode 1304 may be grounded or coupled to an RF generator (not shown), and the lower electrode 1308 is coupled to an RF generator 1318 via a matching network 1314. The RF generator 1318 provides an RF signal between the upper electrode 1304 and the lower electrode 1308 to generate RF power at one or more (e.g., two or three) different RF frequencies. At least one of the multiple RF frequencies may be turned on or off depending on the desired configuration of the vacuum chamber 1300 for a particular operation. In the embodiment shown in FIG. 13, the RF generator 1318 is configured to provide at least three different frequencies, e.g., 400 kHz, 2 MHz, 27 MHz, and 60 MHz, although other frequencies are possible.

[0047] The vacuum chamber 1300 includes a gas showerhead on a top electrode 1304 for introducing process gases provided by one or more gas sources 1322 into the vacuum chamber 1300, and a perforated confinement ring 1312 through which gases can be pumped out of the vacuum chamber 1300 (for example) through a foreline of a foreline assembly by a gas pump 1320. In some exemplary embodiments, the gas pump 1320 is a turbomolecular pump, although other types of gas pumps may be utilized.

[0048] When the substrate 1306 is in the vacuum chamber 1300, a silicon focus ring 1310 is positioned next to the substrate 1306 such that a uniform RF field exists at the bottom surface of the plasma 1302 for uniform etching (or deposition) on the surface of the substrate. The embodiment of Figure 13 shows a triode reactor configuration in which the top electrode 1304 is surrounded by a symmetric RF ground electrode 1324. An insulator 1326 is a dielectric that insulates the ground electrode 1324 from the top electrode 1304. Other implementations of the vacuum chamber 1300, such as ICP-based implementations, are possible without changing the scope of the disclosed examples.

[0049] As used herein, the term "substrate" refers to a supporting material on or within which elements of a semiconductor device are fabricated or attached. For example, a substrate (e.g., substrate 106) may include a wafer (e.g., 100 mm, 150 mm, 200 mm, 300 mm, 450 mm, or more in diameter) composed of, for example, elemental semiconductor materials (e.g., silicon (Si) or germanium (Ge)) or compound semiconductor materials (e.g., silicon germanium (SiGe) or gallium arsenide (GaAs)). In addition, other substrates include, for example, dielectric materials such as quartz or sapphire, on which semiconductor materials can be applied. Exemplary substrates include blanket substrates and patterned substrates. A blanket substrate is a substrate that includes a low surface (or planar) top surface. A patterned substrate is a substrate that includes a high surface (or structured) top surface. The structured top surface of the substrate may include various large surface area structures, such as 3D NAND memory holes or other structures.

[0050] Each frequency generated by the RF generator 1318 may be selected for a specific purpose in the substrate fabrication process. The example of FIG. 13 uses RF power provided at 400 kHz, 2 MHz, 27 MHz, and 60 MHz, with the 400 kHz or 2 MHz RF power providing ion energy control and the 27 MHz and 60 MHz power providing control of plasma density and chemical dissociation patterns. This configuration, in which each RF power can be turned on or off, enables certain processes that use very low ion energy on the substrate and certain processes that require low ion energy (e.g., less than 700 or 200 eV) (e.g., soft etching of low-k materials).

[0051] In another embodiment, 60 MHz RF power is used at the top electrode 1304 to obtain very low energy and very high density. This configuration allows for high density plasma chamber cleaning while minimizing sputtering of the electrostatic chuck (ESC) surface when the substrate 106 is not in the vacuum chamber 1300. When the substrate X06 is not present, the ESC surface is exposed and any ion energy to that surface should be avoided. Therefore, the bottom 2 MHz and 27 MHz power supplies may be turned off during cleaning.

[0052] In an exemplary embodiment, the vacuum chamber 1300 further includes a sensor 1328 that may be disposed between the matching network 1314 of the RF generator 1318 and the lower electrode 1308. The sensor 1328 may include a voltage-current (VI) sensor configured to generate a plurality of signals (e.g., sensed data) indicative of at least one signal characteristic of the RF signal generated by the RF generator 1318 at the corresponding plurality of time instances. For example, the VI sensor may generate a plurality of signals indicative of one or more of the following signal characteristics of the RF signal: voltage, current, phase, supply power, and impedance. In some aspects, the plurality of signals generated by the sensor 1328 at the corresponding plurality of time instances may be stored (e.g., in the controller 1316 or an on-chip memory of the sensor 1328) and retrieved later (e.g., by the controller 1316) for subsequent processing. In other aspects, the plurality of signals generated by the sensor 1328 at the corresponding plurality of time instances may be automatically communicated to the controller 1316 as they are generated.

[0053] As discussed above, conventional configurations of external chamber hardware can significantly hinder the creation of common geometries of RF power components and the establishment of symmetric RF power paths. To that end, examples of the present disclosure are directed to providing component geometries for symmetric RF power paths and gas flow symmetry, particularly in multi-station process modules in semiconductor manufacturing applications. RF power path symmetry, or commonality, can be important for wafer processing uniformity in multi-station processing tools, such as the QSM described herein.

[0054] In some examples, providing RF power path symmetry across stations of a QSM may not necessarily mean, for example, that it is "truly" symmetrical about (or within) each station, but may simply mean that any asymmetry in a given RF power path is commonly distributed or shared by each station, i.e., common to each station. In these examples, the RF power paths may be said to be symmetrical in the sense that each station is commonly asymmetrical.

[0055] Asymmetries that are not commonly shared between stations, or even asymmetries that are generally present in the RF power paths, can cause significant problems in substrate manufacturing processes. RF frequencies above 27 MHz, e.g., 40 MHz, 60 MHz, or even 100 MHz, have wavelengths that are not considered long compared to the size of the hardware or system. A given physical asymmetry between stations in the geometric location of the RF power generators becomes very large "relatively" at such short wavelengths compared to wavelengths associated with lower RF powers, for example. Current processes employing very high frequencies further increase the likelihood of asymmetric RF power paths being formed. Furthermore, at such high frequencies, nonlinear circuit elements, including plasmas, can cause, for example, the generation of harmonic frequencies, making it even more difficult to form symmetries due to the prevalence of harmonics that are multiples of the fundamental frequency.

[0056] Some examples seek to provide an RF power path that is symmetrical relative to the center of the chamber or tool, such as the spindle 602 in the center of the QSM 600 described above. In such examples, the spindle 602 serves as the axis of symmetry. Optimizing or improving the symmetry (or common asymmetry) of the RF power path can improve the ability to establish station-to-station matching of RF power and film properties. Symmetrical geometries and configurations of RF power path components, as described herein, seek to make this possible.

[0057] Some examples herein relate to establishing gas flow symmetry in a multi-station process module. Some examples include a foreline assembly configured to enable symmetrical gas flow across stations. Some exemplary configurations of chamber components combine aspects of RF power path symmetry and gas flow symmetry. Exemplary components may include a foreline, a foreline assembly, a valve or valve component, or an RF power path component such as an RF filter or an RF component enclosure. Exemplary component configurations enabling RF power path symmetry, gas flow symmetry, and / or combined RF power path symmetry and gas flow symmetry may include one or more symmetric geometric configurations of components. The symmetric configuration of components may include components common to each station of a multi-station process module.

[0058] Referring again to FIG. 6, below the QSM 600 is visible a section of the foreline assembly 606. This section is referred to as the "third section" of the foreline assembly and is described in more detail below. The foreline assembly 606 includes a lower outlet 616 that can be directly or indirectly connected to a vacuum source 604 and to other downstream components, such as a combination or control valve 614. During wafer processing, the foreline assembly 606 exhausts exhaust gases from each station 608 (process chamber) and from the entire QSM during wafer or substrate processing.

[0059] 7 is a schematic diagram of the underside and associated components of QSM 600. An underside view of the foreline assembly 606 and lift pin actuator assembly 612 is shown. An RF components enclosure 611 is attached to each lift pin actuator assembly 612. As will be described in more detail below, each (top) inlet 712 of the foreline assembly 606 is connected to a respective station (processing chamber) 608 at a respective chamber port.

[0060] Note that in the exemplary foreline assembly 606 configuration, room may be provided to maintain the same orientation of the lift pin actuator assembly 612 relative to the axis of the spindle 602 (or spindle motor 704), i.e., the lift pin actuator assembly 612 follows the same direction in an imaginary concentric circle around the spindle 602. A (lower) outlet 616 of the foreline assembly 606 may be directly or indirectly connected to a vacuum source 604 and a control valve 614. The QSM 600 may include various components and supply lines 702, connectors 706, control wiring 708, and other modules 710 to feed the QSM 600, as shown. Other component and QSM arrangements are possible.

[0061] It should be noted that the geometric position and orientation of each RF component enclosure 611 within its own QSM quadrant, or with respect to its own station 608, is symmetrical with respect to the geometric position and orientation of another RF component enclosure within its own respective quadrant or station 608. In other words, each quadrant can be said to be "clocked" by approximately 90 degrees with respect to adjacent quadrants, but in all other respects the geometric position and orientation of each RF component enclosure within each quadrant is identical. In this sense, the geometry of the RF component enclosures can be said to be symmetrical. The 90 degree "clocking" of the quadrants occurs about the axis of the spindle 602 or spindle motor 704, and thus the axis of the spindle 602 or spindle motor 704 represents the axis of symmetry.

[0062] The symmetrical placement of RF components may also be applied to other components of the RF power path located outside or below the QSM 600. For example, components such as RF power generators or filters. In some examples, geometric symmetry is applied to non-RF components. For example, note that the geometric location and orientation of each lift pin actuator assembly 612 within its own QSM quadrant or relative to its own station 608 is symmetrical to the geometric location and orientation of another lift pin actuator assembly within its own respective quadrant or station 608.

[0063] In some examples, each quadrant of the QSM may have a local "asymmetry," but the local asymmetry is commonized to each quadrant or station, so that the QSM as a whole remains "symmetric." For example, assume that the mounting brackets for the RF component enclosures 611 were manufactured with an error or design flaw that caused the components in the enclosures 611 to be slightly misaligned. The misalignment would typically cause unwanted disturbances in the RF magnetic flux applied to the QSM 600, and perhaps even cause manufacturing errors. However, by being commonly positioned and oriented, the error in each RF component enclosure 611 is, so to speak, evenly distributed and commonized to each quadrant. If necessary, even if a defect occurs in four places, the error can be adjusted in a single process. In this sense, a "symmetry" of the QSM is created, which in some examples allows for consistency of manufacturing processes and conditions between different QSM stations 608, even though a given component of the QSM may have a local defect or misalignment. Particularly when operating at the high frequencies mentioned above, aspects such as predictability, power uniformity, and process consistency can become significant issues in semiconductor manufacturing.

[0064] In some examples, this ability to obtain this functionality and symmetry of the RF power path is made possible by the geometric configuration of the foreline assembly 606. In some examples, the geometric configuration is open and symmetrical. For example, FIG. 8 shows a further pictorial view of the exemplary foreline assembly 606 mounted below the QSM 600. The foreline assembly 606, spindle motor 704, and lift pin actuator assembly 612 are also seen in this view. Note that the exemplary configuration of the foreline assembly 606 ensures sufficient clearance around the spindle motor 704 and other process support components positioned below the QSM 600. This clearance allows for the design and symmetrical placement of RF and other components as described above. For example, the consistent symmetrical orientation of the lift pin actuator assembly 612 allows for uniformity of replacement parts and easy access to the QSM 600 by an operator, for example, during maintenance of the QSM 600 or between wafer processing cycles.

[0065] 9-10 show pictorial views of the foreline assembly 606 not attached to a QSM. The illustrative foreline assembly 606 includes four inlets, including a chamber port 712 in this example. Other numbers or configurations of inlets are possible depending on the process requirements. For example, a 2 inch inlet 712 may include a 4 inch chamber port so that the foreline assembly 606 can be easily attached to an existing port in the in-situ process module (chamber) 608 without modification. The outlet 616 of the foreline assembly 606 can be directly or indirectly connected to a vacuum source at 604. The vacuum pressure and exhaust gas flow through the foreline assembly 606 can be regulated by a control valve, such as a combination control valve 614.

[0066] In some examples, the foreline in the foreline assembly 606 includes three branches. For example, a first branch, or main branch 902, is provided proximate the outlet 616. At the first branch 902, a relatively large diameter pipe section joins two relatively small pipe sections 908, as shown in the example of FIG. 9. The diameter of each of the two (post-branch) forelines 908 closer to the process module 608 may be approximately the same, for example, as shown. In some examples, the diameter of each pipe may differ depending on the process flow or pressure requirements. The first branch 902 may include a plenum chamber 922 that equalizes the vacuum pressure for more even distribution to the bifurcated foreline 908. In another aspect of the direction of exhaust gas flowing downward outward from the process module 908, the two forelines 908 upstream of the first branch 902 merge into one line, and the exhaust gas forms one gas flow.

[0067] The two second branches 904 of the foreline assembly are disposed between the first branches 902 and each pair of inlets 712, as shown. Only one of the two second branches 904 is fully visible in the view of FIG. 9. In some examples, the first and second branches 902 and 904 divide the foreline of the foreline assembly 606 into three sections: a first section 906 extending from the inlet 712 to the two second branches 904, a second section 908 extending from the second branch 904 to the first branch 902, and a third section 910 extending from the first branch 902 to the outlet 616 of the foreline assembly 606.

[0068] The diameter of the foreline in the first section 906 may range from about 1.5 inches to about 2.5 inches. The diameter of the foreline in the second section 908 may range from about 2.5 inches to about 3.5 inches. The diameter of the foreline in the third section 910 may range from about 3.5 inches to about 4.5 inches. In the illustrated example, a 2-3-4 inch foreline assembly 606 is shown, illustrating the use of 2 inch lines in the first section 906, 3 inch lines in the second section 908, and 4 inch lines in the third section 910 of the foreline assembly 606. Other line configurations are possible. In some examples, the diameter of each line in each section 906, 908, and 910 between the inlet 712 or connector is substantially uniform throughout.

[0069] In some examples, a T-piece connector 912 is provided at each second branch 904. An example T-piece connector 912 may include two outwardly converging conical sections that transition a 3 inch foreline diameter to a 2 inch foreline (or vice versa in the direction of exhaust gas flow), as shown. In some examples, the location or separation distance between the T-piece connector 912 and the underside of the QSM 600 may be selected to accommodate other components, such as the lift pin actuator assembly 612, RF components enclosure 611, spindle motor 704, mDSC motor, or eDSC motor.

[0070] In the first section 906, the foreline assembly 606 includes four forelines, each including three substantially right-angled elbows 914 spaced along the foreline. An elbow is provided between each inlet 712 and a respective second branch 904. In some examples, the forelines in the first section 906 are generally continuous and no separable joints or unions are provided. Other arrangements are possible.

[0071] In the second section 908, the foreline assembly 606 includes two forelines, each including one substantially right angle elbow 916 disposed between the first branch 902 and the second branch 904. In some examples, a separable union 918 is provided at or toward the upper end of each elbow 916. Each union 918 may include two opposing flanges 920 that can be bolted together to join each elbow 916 to the outlet port of the T-piece connector 912, as shown. The flanges 920 lie in a horizontal plane, and the positioning of the flanges 920 above the elbows 916 creates symmetry in both halves of the second section 908 in the sense that different "right-handed" or "left-handed" elements in the second section 908 are avoided. The horizontal orientation of the flange 920 allows an operator to easily access the nuts or bolts that pass vertically through the flange 920 to secure the union 918 because the nuts or bolts are accessible from directly below the QSM 600 and do not require lateral space for access. This horizontal orientation of the union 918 and flange 920, along with the improved clearance described above around the spindle motor 704, makes it easier for an operator to maintain the QSM 600.

[0072] The third section 910 of the foreline assembly 606 may include the plenum chamber 922 referenced above and a relatively short length of large diameter foreline extending from the plenum chamber 922 to the outlet 616 of the foreline assembly 606 .

[0073] 11, in some examples, the foreline assembly 606 includes or is connectable to a spool piece 1104. The spool piece 1104 may be inserted between the vacuum source 604 and the outlet 616 of the foreline assembly 606. For convenience, the exemplary spool piece 1104 may include an indicator 1102 that points in the direction of the vacuum source 604. In some examples, the spool piece 1104 includes a low speed pump inlet 1106, a TEOS diverter 1108, and a gas box diverter 1110. In some examples, the spool piece 1104 includes a precursor or other diverter 1112, a Hastings gauge port 1114, and a bellows 1116 to facilitate operator serviceability and adjustment of the spool piece 1104.

[0074] 12, an example method 1200 of providing a symmetric RF power path in a multi-station process tool includes, in operation 1202, providing a multi-station process tool including a plurality of process chambers, each process chamber being located at a station of the multi-station process tool, and, in operation 1204, installing RF power path components associated with each station of the multi-station process tool, the RF power path components being geometrically positioned and oriented such that when energized, a symmetric RF power path is formed relative to an axis of symmetry of the multi-station process tool.

[0075] In some examples, the axis of symmetry is located at a center of the multi-station process tool. In some examples, the center of the multi-station process tool is defined by an axis of a spindle motor of the multi-station process tool.

[0076] In some examples, the RF power path components include an RF component enclosure.

[0077] In some examples, the multi-station process tool includes a quad-station process module (QSM).

[0078] In some examples, method 1200 further includes configuring the QSM for symmetric gas flow, at operation 1206, where configuring the QSM includes at least attaching a foreline assembly to the QSM, the foreline assembly including four inlets, each connectable to a chamber port of a station of the QSM, an outlet connectable directly or indirectly to a vacuum source, a first foreline branch positioned proximate to the outlet of the foreline assembly, and two second foreline branches positioned between the first foreline branch and each pair of inlets, respectively, and the first and second foreline branches dividing the foreline assembly into three sections: a first section extending from the four inlets to the two second foreline branches, a second section extending from the two second foreline branches to the first foreline branch, and a third section extending from the first foreline branch to the outlet of the foreline assembly.

[0079] In some examples, the method 1200 further includes processing the substrate in the QSM using symmetric RF power paths and symmetric gas flows in each station of the QSM.

[0080] Although examples have been described with reference to certain exemplary embodiments or methods, it will be apparent that various modifications and changes can be made to these embodiments without departing from the broader scope of the present embodiments. Thus, the specification and drawings should be considered in an illustrative and not a limiting sense. The accompanying drawings, which form a part of this specification, show, by way of example, and not by way of limitation, specific embodiments in which the subject matter may be practiced. The illustrated embodiments are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed herein. Other embodiments may be utilized, and other embodiments may be derived from the teachings disclosed herein, such that structural and logical substitutions and changes may be made without departing from the scope of the present disclosure. Thus, this detailed description is not to be construed in a limiting sense, and the scope of the various embodiments is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0081] Such embodiments of the inventive subject matter may be referred to herein individually and / or collectively by the term "invention", but this is merely a matter of convenience and is not intended to spontaneously limit the scope of this application to any single invention or inventive concept (if in fact more than one is disclosed). Thus, although specific embodiments have been illustrated and described herein, it should be understood that any configuration calculated to achieve the same purpose may be substituted for the specific embodiment shown. The present disclosure is intended to cover any and all adaptations or modifications of the various embodiments. Combinations of the above embodiments with other embodiments not specifically described herein will be apparent to one of skill in the art upon reviewing the above description.

Claims

1. 1. A multi-station process tool comprising: a plurality of process chambers, each process chamber located at a station of the multi-station process tool; RF power path components associated with each station of the multi-station process tool, the RF power path components being positioned and oriented such that, when energized, a symmetric RF power path is formed with respect to an axis of symmetry of the multi-station process tool; A multi-station process tool comprising:

2. 10. The multi-station process tool of claim 1, A multi-station process tool, wherein the axis of symmetry is located at a center of the multi-station process tool.

3. 3. The multi-station process tool of claim 2, further comprising: A multi-station process tool, wherein the center of the multi-station process tool is defined by an axis of a spindle motor of the multi-station process tool.

4. 10. The multi-station process tool of claim 1, The multi-station process tool, wherein the RF power path components include an RF component enclosure.

5. 10. The multi-station process tool of claim 1, 10. The multi-station process tool of claim 1, comprising a quad-station process module (QSM) having four stations, each station including a process chamber.

6. 6. The multi-station process tool of claim 5, further comprising: A multi-station process tool, wherein a geometric position and orientation of a first RF power path component relative to a first of the four stations of the QSM is symmetrical to a geometric position and orientation of a second RF power path component relative to a second of the four stations of the QSM.

7. 7. The multi-station process tool of claim 6, further comprising: A multi-station process tool, wherein the geometric position and orientation of a first non-RF component relative to the first station is symmetrical to the geometric position and orientation of a second non-RF component relative to the second station of the QSM.

8. 8. The multi-station process tool of claim 7, further comprising: A multi-station process tool, wherein the asymmetry of the RF power path components or the non-RF components is common to each station of the multi-station process tool.

9. 6. The multi-station process tool of claim 5, further comprising: a foreline assembly including four inlets each connectable to a chamber port of a station of the QSM; an outlet connectable directly or indirectly to a vacuum source; a first foreline branch disposed proximate an outlet of the foreline assembly; two second foreline branches, each disposed between the first foreline branch and a respective pair of the four inlets; the first and second foreline branches dividing the foreline assembly into three sections: a first section extending from the four inlets to the two second foreline branches, a second section extending from the two second foreline branches to the first foreline branch, and a third section extending from the first foreline branch to the outlet of the foreline assembly; A multi-station process tool further comprising:

10. 10. The multi-station process tool of claim 9, further comprising: The diameter of each of the forelines in each section is: a direction of gas flow from at least one of the four inlets of the foreline assembly to the outlet increases stepwise at each branch; A multi-station process tool that is constant within each section of the foreline assembly.

11. 11. The multi-station process tool of claim 10, 10. A multi-station process tool, wherein a foreline diameter in the first section ranges from about 1.5 inches to about 2.5 inches, a foreline diameter in the second section ranges from about 2.5 inches to about 3.5 inches, and a foreline diameter in the third section ranges from about 3.5 inches to about 4.5 inches.

12. 12. The multi-station process tool of claim 11, 1. A multi-station process tool, wherein the diameter of the foreline in the first section is approximately 2 inches, the diameter of the foreline in the second section is approximately 3 inches, and the diameter of the foreline in the third section is approximately 4 inches.

13. 13. The multi-station process tool of claim 12, further comprising: The multi-station process tool further comprising a T-piece connector at each of the two second foreline branches.

14. 14. The multi-station process tool of claim 13, the T-piece connector includes an outwardly converging conical section that transitions the diameter of the foreline in the first section to the diameter of the foreline in the second section.

15. 15. The multi-station process tool of claim 14, further comprising: A multi-station process tool, wherein a separation distance between the T-piece connector and an underside of the QSM is configured to accommodate RF power path components between the T-piece connector and an underside of the QSM.

16. 1. A method for providing a symmetric RF power path in a multi-station process tool, comprising: providing a multi-station processing tool including a plurality of process chambers, each process chamber being located at a station of the multi-station processing tool; installing RF power path components associated with each station of the multi-station process tool, the RF power path components being positioned and oriented such that, when energized, they form an RF power path that is symmetrical about an axis of symmetry of the multi-station process tool; A method comprising:

17. 17. The method of claim 16, The method of claim 1, wherein the axis of symmetry is located at a center of the multi-station process tool.

18. 20. The method of claim 17, The method, wherein the center of the multi-station process tool is defined by an axis of a spindle motor of the multi-station process tool.

19. 17. The method of claim 16, The method, wherein the RF power path component comprises an RF component enclosure.

20. 17. The method of claim 16, The method, wherein the multi-station process tool includes a quad-station process module (QSM).

21. 21. The method of claim 20, and configuring the QSM for symmetric gas flow, the configuring the QSM comprising: The method includes at least mounting a foreline assembly to the QSM, the foreline assembly comprising: four inlets each connectable to a chamber port of a station of the QSM; an outlet connectable directly or indirectly to a vacuum source; a first foreline branch disposed proximate an outlet of the foreline assembly; two second foreline branches, each disposed between the first foreline branch and a respective pair of the four inlets; the first and second foreline branches dividing the foreline assembly into three sections: a first section extending from the four inlets to the two second foreline branches, a second section extending from the two second foreline branches to the first foreline branch, and a third section extending from the first foreline branch to the outlet of the foreline assembly; A method comprising:

22. 22. The method of claim 21, The method further comprising processing a substrate in the QSM using the symmetric RF power paths and symmetric gas flows in each station of the QSM.

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