Radio frequency measurements from transmission line sensors

Abstract

Embodiments disclosed herein include a sensor. In one embodiment, a sensor comprises: a plate in which a hole is formed through the plate; a current loop which passes through the plate in a bent manner around the hole; and a voltage loop surrounding the bore and within an inner periphery of the current loop, where the voltage loop includes: an inner loop; an insulating ring surrounding the inner ring; and an outer ring surrounding the insulating ring.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application No. 17 / 737,682, filed on May 5, 2022, the entire contents of which are hereby incorporated by reference. Technical Field

[0003] Embodiments relate to the field of semiconductor manufacturing and, in particular, to sensors for measuring voltage and current in semiconductor tools. Background Art

[0004] In a plasma processing tool, the plasma is ignited by a cathode coupled to a process gas within a chamber. In most tools, a power source is coupled to the cathode through an impedance matching network (sometimes simply referred to as a "match"). The match allows the impedance of the system to be adjusted to match the impedance of the load to which the cathode is coupled. The load has a wide range of impedances that are determined by parameters such as process conditions, chamber configuration, etc. Matching impedance is important to provide efficient power transfer from the source to the load.

[0005] RF coupled sensors are used to provide feedback to change the impedance varying device to change the impedance of the matching piece. However, currently available sensors are not without problems. On the one hand, parasitic effects are not adequately controlled, which limits the effective operating frequency. In addition, sensor parasitic effects and port mutual coupling can weaken the dynamic range of the sensor due to cross coupling. In another issue, multiple sensors built on a common printed circuit board (PCB) can cause coupling between sensors, which can impair sensor measurements. Summary of the invention

[0006] Embodiments disclosed herein include sensors. In one embodiment, the sensor includes: a plate, wherein a hole is formed through the plate; a current loop, the current loop winding around the hole through the plate; and a voltage ring, the voltage ring surrounding the hole and within the inner periphery of the current loop, wherein the voltage ring includes: an inner ring; an insulating ring, the insulating ring surrounding the inner ring; and an outer ring, the outer ring surrounding the insulating ring.

[0007] In another embodiment, a sensor is described. In one embodiment, the sensor includes: a board, wherein a hole is provided through the board; a current loop, the current loop surrounding the hole, wherein the current loop includes: a set of inner through holes; a set of outer through holes; and a plurality of conductive traces, wherein each conductive trace couples a through hole in the set of inner through holes to a through hole in the set of outer through holes, and wherein the plurality of conductive traces are alternately located on a top surface of the board and on a bottom surface of the board; and a voltage ring, the voltage ring within an inner perimeter of the current loop, wherein the voltage ring includes: an inner ring; an insulating ring, the insulating ring surrounding the inner ring; and an outer ring, the outer ring surrounding the insulating ring.

[0008] In one embodiment, a processing tool is described. In one embodiment, the processing tool includes: a power supply; an impedance matching network, the impedance matching network is coupled to the power supply; a cathode, wherein the power supply is configured to supply power to the cathode through the impedance matching network; a processing module, wherein the processing module is communicatively coupled to the power supply and the impedance matching network; a first sensor and a second sensor, the first sensor is disposed upstream of the impedance matching network, and the second sensor is disposed downstream of the impedance matching network, wherein each of the first sensor and the second sensor includes: a plate, wherein a hole is formed through the plate; a current loop, the current loop passes through the plate in a meandering manner around the hole; and a voltage ring, the voltage ring surrounds the hole and is within the inner periphery of the current loop, wherein the voltage ring includes: an inner ring; an insulating ring, the insulating ring surrounds the inner ring; and an outer ring, the outer ring surrounds the insulating ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of a plasma processing tool including a centralized control architecture according to one embodiment.

[0010] Figure 2A is a plan view illustration of a current loop of a sensor according to an embodiment.

[0011] Figure 2B is a plan view illustration of a voltage loop of a sensor according to an embodiment.

[0012] Figure 3A is a plan view illustration of a sensor having a current loop, a voltage loop, and a guard ring according to an embodiment.

[0013] Figure 3B is a plan view illustration of a printed circuit board having a pair of sensors according to one embodiment.

[0014] Figure 4A is a plan view illustration of a sensor having multiple baluns coupled to a current loop according to an embodiment.

[0015] Figure 4B is a circuit diagram of a balun that may be used in a sensor according to an embodiment.

[0016] Figure 5A is a perspective view illustration of a sensor according to an embodiment.

[0017] Figure 5B is a perspective view illustration of a ground plate having cutouts for sensors according to an embodiment.

[0018] Figure 5C is a perspective view illustration of a sensor inserted into a ground plate according to an embodiment.

[0019] Fig. 6A is a plan view illustration of a ground plate for a symmetric cathode including a cutout for a sensor according to an embodiment.

[0020] Figure 6B is a plan view illustration of a ground plate with a sensor inserted into a cutout according to an embodiment.

[0021] Figure 7 A block diagram is shown of an exemplary computer system that may be used in conjunction with a processing tool according to an embodiment. DETAILED DESCRIPTION

[0022] The systems described herein include sensors for measuring voltage and current in semiconductor tools from transmission line sensors. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent to those skilled in the art that the embodiments may be practiced without these specific details. In other instances, well-known aspects are not described in detail so as not to unnecessarily obscure the embodiments. Furthermore, it should be understood that the various embodiments shown in the drawings are illustrative representations and are not necessarily drawn to scale.

[0023] As described above, existing sensor devices are limited. Therefore, the impedance matching network cannot operate under ideal conditions. Therefore, embodiments disclosed herein include sensors with improved performance. As used herein, a sensor may refer to a sensor capable of measuring current and / or voltage along a coaxial transmission line portion. In a specific embodiment, the sensor includes a hole, and a conductive device passes through the hole, the conductive device having a concentric electrically insulating material (e.g., an RF cable). Features on the sensor are capable of acquiring current and voltage transmitted along the transmission line. For example, a current loop detects current and a voltage loop detects voltage. Current and voltage measurements can then be used as sensor measurement feedback to indicate changes in the impedance of the impedance matching network.

[0024] In a specific embodiment, the sensor described herein exhibits reduced parasitic coupling between detection elements. This allows a larger dynamic range to be achieved over a wider operating frequency range. In some embodiments, a balun is included along the current loop. This allows increased amplification and magnetic field coupling of current loop induction. In yet another embodiment, the isolation between the sensor detection elements (for current and voltage) reduces the cross coupling between the sensor ports. This allows a larger dynamic range to be achieved over a wider operating frequency range. Some embodiments may include multiple sensors within a single printed circuit board (PCB). In such an embodiment, a guard ring may be provided around each sensor to eliminate cross coupling between concentric sensor elements. This may achieve high fidelity measurements and accuracy over a wider dynamic range while broadening the frequency range.

[0025] In a specific embodiment, the sensor described herein is part of a plasma processing tool. Typically, the plasma processing tool includes a chamber with a cathode. A power architecture provides power to the cathode. For example, the power architecture includes one or more power supplies and an impedance matching network. The sensor described herein can be provided upstream of the impedance matching network and / or downstream of the impedance matching network. The sensor can provide feedback to a process power processing module that controls the power supply and sheath voltage coupled to the body of the plasma and the impedance matching network.

[0026] Reference now Figure 1 , a more detailed schematic diagram of a plasma processing tool 100 is shown according to one embodiment. In one embodiment, the plasma processing tool 100 includes a plasma chamber 120. The plasma chamber 120 includes a cathode 122 to couple received power to one or more gases flowing into the plasma chamber 120. In one embodiment, the plasma chamber 120 can be suitable for any plasma process of a typical semiconductor manufacturing environment. For example, the plasma chamber 120 can be a plasma etching chamber, a plasma deposition chamber, a plasma processing chamber, etc. In a specific embodiment, the plasma chamber 120 can be a plasma enhanced chemical vapor deposition (PECVD) chamber, a physical vapor deposition (PVD) chamber, or a plasma enhanced atomic layer deposition (PEALD) chamber.

[0027] In one embodiment, the plasma chamber 120 can be coupled to a power delivery architecture. For example, the power delivery architecture can include one or more power supplies 1321-132 nIn the illustrated embodiment, multiple power supplies 132 are shown. However, it should be understood that a single power supply 132 may be used in some embodiments. In an embodiment, the power supply 132 may include any type of power supply. For example, the power supply 132 may be an RF power supply, a microwave power supply, a direct current (DC) power supply, a pulsed DC power supply, etc. The transmission line sensor with an extended dynamic range and a widened operating frequency response supports a wider range of plasma drive power supplies.

[0028] In one embodiment, the power source 132 may be coupled to the cathode 122 via an impedance matching network 130. The impedance matching network 130 adjusts the impedance of the power delivery architecture to match the load in the chamber 120. Due to changes in processing conditions (e.g., gas flow rate, pressure, temperature, etc.), the impedance of the load may change. Therefore, the impedance matching network 130 is used to match the changing impedance in order to provide efficient and optimal power delivery (i.e., no or minimal reflected power) to the coupled plasma in the chamber.

[0029] In one embodiment, sensors 151 and 152 may be disposed at opposite ends of the impedance matching network 130. For example, sensors 1511-151 n The sensor 152 may be on the upstream side of the impedance matching network 130, while the sensor 154 may be on the downstream side of the impedance matching network 130. The "upstream" side may refer to the input side of the impedance matching network 130, and the "downstream" side may refer to the output side of the impedance matching network 130. As shown in the figure, multiple sensors 1511-151 n The impedance matching network 130 is provided on the upstream side. The number of sensors 151 can be equal to the number of power sources 132. In other words, each power source 132 can have a dedicated sensor 151. The downstream side of the impedance matching network 130 can have a single sensor 152. However, it should be understood that when there is more than one output from the matching network 130, there may be additional sensors 152. For example, in the case of two outputs (e.g., for the center of the chamber 120 and the edge of the chamber 120), there may be two sensors 152.

[0030] In the case of multiple sensors 151, multiple sensors 151 1-n Can be manufactured on a single PCB. That is, a single module can include multiple sensors. A more detailed description of multi-sensor implementations is provided below. In general, the implementations described herein include electrical shielding techniques that limit cross coupling between sensors on a single PCB.

[0031] exist Figure 1, sensors 151 and 152 are generally shown as boxes. However, it should be understood that sensors 151 and 152 can be similar to any sensor architecture described in more detail below. For example, each sensor 151 and / or 152 can be a voltage and current (i.e., V / I) sensor. The voltage can be detected by an embedded voltage loop and the current can be detected by a current loop. Each sensor has a hole through which a conductive device (e.g., an RF cable) with concentric electrically insulating material passes.

[0032] In one embodiment, sensors 151 and 152 may be communicatively coupled to processing module 134. As shown, Figure 1 100. However, it should be understood that the processing module can be a microwave processing module 134, a DC processing module, an RF processing module, etc., depending on what type of power supply 132 is included in the tool 100. In one embodiment, sensors 151 and 152 deliver voltage and / or current to the processing module 134. In one embodiment, the processing power control module 134 can have external connections for different physical layers and protocols, such as Ethernet (ENET) and standardized industrial connections, such as EtherCAT.

[0033] In one embodiment, the processing module 134 can be coupled to the impedance matching network. The processing module 134 can be capable of sending a control signal to the impedance matching network 130. For example, the control signal can be used to adjust the capacitance of a variable capacitor within the impedance matching network 130. In addition, the processing module 134 can be coupled to the power supply 132. Thus, the processing module 134 can coordinate impedance tuning.

[0034] Reference now Figure 2A , according to one embodiment, a plan view of a portion of a sensor 250 is shown. In one embodiment, the sensor 250 may include a PCB 253. The PCB 253 may include two or more wiring layers. The wiring layers may be separated from each other by a dielectric layer. In one embodiment, vias may pass through the dielectric layer to provide electrical coupling between the wiring layers.

[0035] In one embodiment, the sensor 250 may include a current loop 254. The current loop 254 may include one or more conductive windings that wrap around a hole 260 that passes through the PCB 253. Figure 2AIn the particular embodiment shown, the current loop 254 includes two windings. However, it should be understood that in other embodiments, one winding or more than two windings may be used. In one embodiment, each winding is composed of a trace 256 (solid line) on the top surface of the PCB 253 and a trace 257 (dashed line) on the bottom surface of the PCB 253. The transition through the PCB 253 can be provided by a through hole 255. As shown, the through hole 255 is provided around the hole 260. A The first concentric ring and the through hole 255 B Each through hole 255 A Both with a through hole 255 B In some cases, via 255 A It can be called an external through hole, while the through hole 255 B It can be called an internal through hole.

[0036] As shown, the windings alternate between being implemented as traces 256 on the top surface of PCB 253 and being implemented as traces 257 on the bottom surface of PCB 253. In addition, each winding is connected to the inner via 255. B and external through hole 255 A In addition, the windings are interlaced. For example, in the first pair of through holes 255 A and 255 B The adjacent second pair of through holes 255 A and 255 B In between, the first winding can be run along the top surface of PCB 253 as trace 256, and the second winding can be run along the bottom surface of PCB 253 as trace 257.

[0037] In one embodiment, the first end of the current loop 254 can be coupled to the pad 2591 through the trace 258. Similarly, the second end of the current loop 254 can be coupled to the pad 2592 through the trace 258. In one embodiment, the first end of the current loop 254 and the second end of the current loop 254 can be disposed on the same surface of the PCB 253. For example, Figure 2A , pads 2591 and 2592 are disposed on the top surface of PCB 253 .

[0038] In the illustrated embodiment, sixteen internal through holes 255 are shown. B and sixteen external through holes 255 A (Thirty-two through holes 255 in total). However, it should be understood that more or fewer through holes 255 may be used according to various embodiments. In one particular embodiment, there may be twenty-four inner through holes 255. B and twenty-four external through holes 255 A(Forty-eight through holes 255 total.) In some cases, increasing the number of through holes 255 may increase the degree of coupling with the magnetic field of the cable passing through hole 260. In this way, improved sensor performance may be achieved.

[0039] Reference now Figure 2B , according to one embodiment, a plan view of a portion of a sensor 250 is shown. In one embodiment, Figure 2B 250 illustrates a voltage sensing structure. For example, an embedded voltage ring 265 can be inserted into the PCB 253 around the hole 260. More specifically, it is noted that the voltage ring 265 is physically inserted into the PCB 253, rather than being etched from conventional PCB material. This creates a 3D type PCB assembly. Although shown as different sensors 250 for clarity, it should be understood that the current loop 254 and the voltage ring 265 can be implemented on a single PCB 253. In such an embodiment, the voltage ring 265 can be arranged around the hole 260 within the inner perimeter of the current loop 254.

[0040] In one embodiment, the voltage ring 265 may include a first conductive ring 266 and a second conductive ring 268. In one embodiment, an insulating ring 267 may be disposed between the first conductive ring 266 and the second conductive ring 268. In a specific embodiment, the first conductive ring 266 and the second conductive ring 268 may include copper or another conductive material. The first conductive ring 266 and the second conductive ring 268 may be concentric rings with each other. The thickness of the first conductive ring 266 and the second conductive ring 268 may be substantially equal to the thickness of the PCB 253.

[0041] In one embodiment, the first ring 266 can be used as a voltage detection surface. The second ring 268 can be grounded. That is, the second ring 268 can be connected to an electrical ground. Although not shown, it should be understood that the tabs connected to the first ring 266 and / or the second ring 268 can be folded over the top and / or bottom surface of the insulating ring 267. In one embodiment, the embedded voltage ring 265 is concentric with the hole 260 passing through the PCB 253. In one embodiment, the embedded voltage ring 265 is inserted into the hole 260. In another embodiment, the embedded voltage ring is internally embedded in the structure of the PCB 253.

[0042] Reference now Figure 3A , a plan view of a sensor 350 is shown according to an embodiment. As shown, the sensor 350 is fabricated on a PCB 353. The sensor 350 may include a current loop 354 and a voltage loop 365 within the current loop 354. The current loop 354 and the voltage loop 365 may surround a hole 360 ​​passing through the PCB 353.

[0043] In one embodiment, the current loop 354 may include an inner via 355 B and external through hole 355 A The vias 355 may be coupled to each other via traces 356 on the top surface of the PCB 353 and traces 357 on the bottom surface of the PCB 353. In the illustrated embodiment, the current loop 354 includes a pair of windings around the hole 360. In one embodiment, the current loop 354 may be substantially similar to the current loop 254 described in more detail above.

[0044] In one embodiment, the voltage ring 365 may include an inner conductive ring 366 and an outer conductive ring 368. An insulating ring 367 may be disposed between the inner ring 366 and the outer ring 368. The inner ring 366 may be a voltage sensing surface and the outer ring 368 may be grounded. In one embodiment, the inner ring 366 may define an outer perimeter of the hole 360. The voltage ring 365 may be substantially similar to the voltage ring 265 described in more detail above.

[0045] In one embodiment, the sensor 350 may also include a guard ring 370 around the outer periphery of the current loop 354. In one embodiment, the guard ring 370 may be grounded. The guard ring 370 may include a through hole (not shown) that couples the guard ring 370 to a ring of similar size and shape on the bottom side of the PCB 353. In this way, an electrical shielding barrier is provided around the detection component of the sensor 350. Therefore, the sensor performance can be improved.

[0046] In one embodiment, the voltage ring 365 can be coupled to the detection circuitry 381 on the PCB 353. Figure 3A The detection circuit system 381 in is schematically shown as a dashed box. However, it should be understood that the detection circuit system 381 may include features such as filters, amplifiers, and the like. In one embodiment, a pad 383 is provided. The pad 383 may be suitable for attaching a connector (not shown) to feed voltage information back to a processing module, such as the processing module described in more detail above.

[0047] In one embodiment, the current loop 354 can be coupled to the detection circuitry 382 on the PCB 353. Figure 3A The detection circuit system 382 in is schematically shown as a dashed box. However, it should be understood that the detection circuit system 382 may include features such as filters, amplifiers, and the like. In one embodiment, a pad 384 is provided. The pad 384 may be suitable for attaching a connector (not shown) to feed current information back to a processing module, such as the processing module described in more detail above.

[0048] In one embodiment, the detection circuit system 381 is electrically isolated from the detection circuit system 382. Electrically isolating the two sets of detection circuit systems 381 and 382 can reduce the cross coupling between the two circuits. In this way, the performance of the sensor 350 can be improved. In one embodiment, the electrical isolation can be provided by a conductive strip 385 disposed between the two sets of detection circuit systems 381 and 382. In one embodiment, the conductive strip 385 can be grounded. In some embodiments, the conductive strip 385 is electrically coupled to the guard ring 370. The conductive strip 385 can be disposed on the top surface of the PCB 353. In other embodiments, a through hole can be provided below the strip 385 so that the electrical isolation extends through the thickness of the PCB 353.

[0049] Reference now Figure 3B , according to an additional embodiment, a plan view of a sensor 350 is shown. Figure 3B In the illustrated embodiment, the sensor 350 may include a pair of holes 3601 and 3602. Each hole 360 ​​may be surrounded by a current loop 354 and a voltage loop 365. For example, the current loop 3541 and the voltage loop 3651 are around the hole 3601, and the current loop 3542 and the voltage loop 3652 are around the hole 3602. Similarly, a first guard ring 3701 may be around the current loop 3541, and a second guard ring 3702 may be around the current loop 3542. Although two sets of sensing elements are shown, it should be understood that any number of holes 360 and corresponding current loops 354, voltage loops 365, and guard rings 370 may be included on the PCB 353. The current loop 354 and the voltage loop 365 may be substantially similar to the current loop 254 and the voltage loop 265 described in more detail above. -

[0050] like Figure 3B As shown, guard ring 370 includes through hole 371. Through hole 3711 is below guard ring 3701, and through hole 3712 is below guard ring 3702. In one embodiment, the positioning of through holes 3711 and 3712 can be rotated relative to each other. Rotating the positioning of through hole 371 can produce even greater electrical isolation between the two sets of detection elements.

[0051] In one embodiment, voltage loop 3651 may be coupled to detection circuitry 3811 and pad 3831, and current loop 3541 may be coupled to detection circuitry 3821 and pad 3841. Similarly, voltage loop 3652 may be coupled to detection circuitry 3812 and pad 3832, and current loop 3542 may be coupled to detection circuitry 3822 and pad 3842. Detection circuitry 381 / 382 may be substantially similar to the detection circuitry described in more detail above.

[0052] To provide electrical isolation between various instances of detection circuitry 381 / 382, conductive strips 3851 and 3852 may be provided. To provide electrical isolation between detection circuitry 3821 and 3812, conductive strip 386 may be provided. Conductive strips 385 and 386 may be on the top surface of PCB 353. In other embodiments, vias under conductive strip 385 may extend the electrical isolation through the thickness of PCB 353. In one embodiment, conductive strips 385 and 386 may be connected to ground.

[0053] Reference now Figure 4A , a plan view of a sensor 450 is shown according to one embodiment. In one embodiment, the sensor 450 may include a PCB 453 having a hole 460. In one embodiment, the detection element may include a current loop 454 and a voltage loop 465. The current loop 454 and the voltage loop 465 may be substantially similar to the current loop and the voltage loop described in more detail above. In one embodiment, the sensor 450 may also include a guard ring 470 around the outer periphery of the current loop 454.

[0054] In one embodiment, the current loop 454 may be electrically coupled to one or more baluns 475 . Figure 4A The balun 475 in is shown as being disposed in a cutout in the guard ring 475. However, it should be understood that the balun 475 can be disposed at any convenient location on the PCB 453. In the illustrated embodiment, four baluns 475 are provided. However, it should be understood that any number of baluns 475 can be used. The presence of the balun 475 can increase the signal-to-noise ratio and achieve improved sensor performance. In a particular embodiment, each balun 475 can double the amount of current. In one embodiment, the transformer arrangement is evenly distributed for each loop, and each transformer arrangement is geometrically positioned 180 degrees relative to another transformer arrangement paired therewith. For example, a four-transformer arrangement will place a pair in each loop, and the pairs are radially separated by 180 degrees.

[0055] Reference now Figure 4B , a circuit of a balun 475 is shown according to one embodiment. In one embodiment, the balun 475 may include a transformer-based circuit system. Figure 4B A specific balun 475 architecture is shown in FIG. 4 , but it should be understood that the balun 475 circuitry may include any suitable structure that provides balun functionality.

[0056] Reference now Figure 5A, a perspective view of a sensor 550 is shown according to one embodiment. In one embodiment, the sensor 550 may include a generally circular end 547 and a rectangular end 548. The circular end 547 may include a hole 560 through which a cable or the like passes. In one embodiment, a current loop and a voltage loop are provided around the hole 560 (neither shown for simplicity). In one embodiment, the rectangular end 548 may be used to support a detection circuit system and a connector.

[0057] Reference now Figure 5B , according to one embodiment, a perspective view of a ground plate 590 for fixing a cathode device is shown. As shown, the ground plate 590 can include a cutout 591 that substantially matches the shape of the sensor 550. The depth of the cutout 591 can substantially match (or be greater than) the thickness of the sensor 550. In one embodiment, the cutout 591 is above a hole 561 through the ground plate 590. The hole 561 can be the location where a cable (e.g., an RF cable) passes through the ground plate 590.

[0058] Reference now Figure 5C , according to one embodiment, a plan view of a ground plate 590 after inserting a sensor 550 is shown. As shown, a hole 560 in the sensor 550 is aligned with a hole 561 to allow a cable to pass through. The cable induces the sensor detection surface (e.g., current loop and voltage loop) to detect current and voltage, and the detection results can be fed back to the processing power processing module. For example, the feedback can be used in part to control an impedance matching network or processing power that contributes to the plasma density and / or plasma sheath voltage.

[0059] Reference now Fig. 6A , according to one embodiment, a plan view illustration of a ground plate 695 for a symmetric cathode is shown. Figures 5A to 5C Similar to the embodiment described in , the ground plate 695 may include a cutout 691 sized to receive the sensor.

[0060] Reference now Figure 6B , according to one embodiment, a plan view of ground plate 695 is shown after sensor 650 is inserted into cutout 691. As shown, hole 660 of sensor 650 is positioned so that it receives a cable. Voltage and current of the cable can be measured by sensor 650.

[0061] Although two examples of integrating sensors into a plasma tool are shown, it should be understood that embodiments are not limited to such configurations. For example, other plasma tool architectures may require moving the sensor to a different location other than the ground plate. In addition, similar sensor architectures can be used to measure current and voltage before the impedance matching network, as described in more detail above. That is, embodiments generally include sensors that measure current and voltage by using a current loop and a voltage loop concentrically formed around the hole.

[0062] Reference now Figure 7 , a block diagram of an exemplary computer system 700 of a processing tool is shown according to an embodiment. In one embodiment, the computer system 700 is coupled to the processing tool and controls the processing in the processing tool. The computer system 700 can be connected (e.g., network connection) to other machines in a local area network (LAN), an internal network, an external network, or the Internet. The computer system 700 can operate as a server or client machine in a client-to-server network environment, or can operate as a peer machine in a peer (or distributed) network environment. The computer system 700 can be a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a cellular phone, a network device, a server, a network router, a switch or a bridge, or any machine that can perform a set of instructions specifying the action that this machine will take (sequentially or otherwise). In addition, although only a single machine is shown for the computer system 700, the term "machine" should also be considered to include a set of any machines (e.g., computers) that execute a set (or multiple sets) of instructions to perform any one or more methods described herein, either individually or jointly.

[0063] The computer system 700 may include a computer program product or software 722 having a non-transitory machine-readable medium having instructions stored thereon, which may be used to program the computer system 700 (or other electronic device) to perform processing according to an embodiment. A machine-readable medium includes any mechanism for storing or transmitting information in a machine (e.g., computer) readable form. For example, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., computer) readable storage medium (e.g., read-only memory ("ROM"), random access memory ("RAM"), disk storage medium, optical storage medium, flash memory device, etc.), a machine (e.g., computer) readable transmission medium (electrical, optical, acoustic or other form of propagation signal (e.g., infrared signal, digital signal, etc.)), etc.

[0064] In one embodiment, the computer system 700 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 an auxiliary memory 718 (e.g., a data storage device), which communicate with each other via a bus 730.

[0065] The system processor 702 represents one or more general-purpose processing devices, such as a microsystem processor, a central processing unit, etc. More specifically, the system processor may be a complex instruction set computing (CISC) microsystem processor, a reduced instruction set computing (RISC) microsystem processor, a very long instruction word (VLIW) microsystem processor, a system processor implementing other instruction sets, or a system processor implementing a combination of instruction sets. The 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), a network system processor, etc. The system processor 702 is configured to execute processing logic 726 for performing the operations described herein.

[0066] The computer system 700 may also include a system network interface device 708 for communicating with other devices or machines. The computer system 700 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 generating device 716 (e.g., a speaker).

[0067] The secondary memory 718 may include a machine-accessible storage medium 732 (or more specifically, a computer-readable storage medium) having stored thereon 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, in whole or in part, within the main memory 704 and / or within the system processor 702 during execution by the computer system 700, the main memory 704 and the system processor 702 also constituting machine-readable storage media. The software 722 may also be transmitted or received over the network 720 via the system network interface device 708. In one embodiment, the network interface device 708 may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.

[0068] Although the machine-readable storage medium 732 is shown as a single medium in the exemplary embodiment, the term "machine-readable storage medium" should be considered to include a single medium or multiple media (such as a centralized or distributed database, and / or associated caches and servers) that store one or more sets of instructions. The term "machine-readable storage medium" should also be considered to include any medium capable of storing or encoding a set of instructions to be executed by a machine and causing the machine to perform any one or more of the methods. Therefore, the term "machine-readable storage medium" should be considered to include, but not limited to, solid-state memories, and optical and magnetic media.

[0069] In the foregoing specification, specific exemplary embodiments have been described. It will be apparent 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 rather than a restrictive sense.

Claims

1. A sensor, comprising: a plate, wherein a hole is formed through the plate; a current loop passing through the plate in a zigzag manner around the hole; and a voltage ring surrounding the aperture and within an inner perimeter of the current loop, wherein the voltage ring comprises: Inner ring; an insulating ring surrounding the inner ring; and An outer ring surrounds the insulating ring.

2. The sensor of claim 1, wherein the current loop comprises a first winding and a second winding.

3. The sensor of claim 1, wherein the current loop comprises sixteen or more vias passing through the board.

4. The sensor of claim 1, further comprising: A balun is provided along the current loop.

5. The sensor of claim 4, further comprising: There are four baluns in total, which are arranged along the current loop.

6. The sensor of claim 1, further comprising: A guard ring surrounds the current loop.

7. The sensor of claim 1, wherein a set of detection circuitry for the current loop is electrically isolated from a set of detection circuitry for the voltage loop.

8. The sensor of claim 7, wherein the isolation feature between the current loop and the voltage loop is a ground via through the board.

9. The sensor of claim 1, wherein the inner ring is the electric field sensing surface, and wherein the outer ring is grounded.

10. The sensor of claim 1, further comprising: a second hole extending through the plate; a second current loop surrounding the second aperture; and A second voltage loop is provided, wherein the second voltage loop is within a perimeter of the current loop.

11. The sensor of claim 10, further comprising: a first guard ring, the first guard ring surrounding the current loop; and A second guard ring surrounds the second current loop. 12 . The sensor of claim 11 , wherein the position of the second through hole of the second guard ring is rotated relative to the position of the first through hole of the first guard ring.

13. A sensor comprising: a plate, wherein an aperture is provided through said plate; a current loop surrounding the aperture, wherein the current loop comprises: a set of internal through holes; a set of external through holes; and a plurality of conductive traces, wherein each conductive trace couples a via in the set of inner vias to a via in the set of outer vias, and wherein the plurality of conductive traces are alternately located on a top surface of the board and on a bottom surface of the board; and a voltage ring within an inner periphery of the current loop, wherein the voltage ring comprises: Inner ring; an insulating ring surrounding the inner ring; and An outer ring surrounds the insulating ring.

14. The sensor of claim 13, wherein the number of the set of inner through holes is equal to the number of the set of outer through holes.

15. The sensor of claim 13, further comprising: A plurality of baluns are coupled to the current loop.

16. The sensor of claim 13, further comprising: A guard ring surrounds the current loop.

17. The sensor of claim 13, wherein a set of detection circuitry for the current loop is electrically isolated from a set of detection circuitry for the voltage loop.

18. A processing tool comprising: power supply; an impedance matching network coupled to the power source; a cathode, wherein the power supply is configured to supply power to the cathode through the impedance matching network; a processing module, wherein the processing module is communicatively coupled to the power source and the impedance matching network; A first sensor and a second sensor, wherein the first sensor is disposed upstream of the impedance matching network, and the second sensor is disposed downstream of the impedance matching network, wherein each of the first sensor and the second sensor comprises: a plate, wherein a hole is formed through the plate; a current loop that passes through the plate in a zigzag manner around the hole; and a voltage ring surrounding the aperture and within an inner perimeter of the current loop, wherein the voltage ring comprises: Inner ring; an insulating ring surrounding the inner ring; and An outer ring surrounds the insulating ring.

19. The processing tool of claim 18, wherein the current loop comprises a first winding and a second winding.

20. The processing tool of claim 18, further comprising: A guard ring surrounds the current loop.

Images