Controller for matching unit in plasma processing system

Abstract

To provide a controller for a matching unit in a plasma processing system.SOLUTION: A matching unit controller is provided that operates in combination with a matching unit for a plasma processing machine. The controller has a master controller application and functions as a local master in the matching unit. The controller collects data from an input sensor and an output sensor, and transmits the data to an intelligent algorithm. An output from the algorithm is used to set the location of a capacitor of the matching unit. The controller also has a slave controller application and communicates with a master controller of the plasma processing machine.SELECTED DRAWING: Figure 1

Description

Technical field

[0001] Technical field The present invention relates generally to control systems for RF matching networks (units) used in plasma processing machines and other RF powering applications. [Background technology]

[0002] background Plasma processing is used extensively in the manufacture of semiconductor devices, solar cells, flat panel displays, and certain medical devices, to name just a few applications. One of the most common methods for activating plasma processing is to supply RF (radio frequency) power to a processing chamber containing a processing gas mixture. Some of the parent gas atoms or molecules are ionized, thus creating a sufficient number of free electrons and ions to form a plasma (also known as the fourth state of matter). The plasma conditions produce highly reactive ionic species that rain down on the workpiece introduced into the plasma chamber. These bombarded ionic species modify the work piece surface to produce predefined structures, functions, or surface properties.

[0003] In a typical RF plasma process, RF power is coupled through an electrode or antenna to the gas mixture within the chamber to excite a plasma state. Radio frequency power is most commonly delivered at 13.56 MHz, but frequencies from tens of kilohertz to hundreds of megahertz are also commonly found. An RF generator supplies power to the processing chamber through a transmission line. To optimize power coupling, the transmission line characteristic impedance is matched to the generator output impedance, typically 50 ohms. Ideally, the chamber impedance should also be 50 ohms to avoid impedance mismatches and to avoid power reflecting back to the generator. Unfortunately, it is unlikely that a plasma chamber will have a characteristic impedance of 50 ohms at all frequencies and plasma conditions. Therefore, an intermediate circuit is used to match the impedance of the RF generator, transmission line, and plasma chamber. This intermediate circuit with adjustable impedance is commonly known as an RF impedance matching network.

[0004] An RF match network transforms the RF impedance of the plasma chamber to 50 ohms to maximize power delivery from the generator. In other words, the matching network (circuit) and plasma chamber combination is 50 ohms measured in the plane where the transmission line is connected. A typical RF matching network includes an input power sensor, a variable capacitor, an inductor, and a controller circuit in which a self-tuning matching algorithm can be programmed into a microprocessor or microcontroller. The topography of the matching network (circuit) and the values / sizes of the variable capacitors / inductors that make up the RF matching network are determined by the power supply requirements, operating frequency, and impedance range of the plasma processing chamber.

[0005] Types of input sensors commonly used in RF matching network applications are directional couplers and phase / magnitude detectors. VI (voltage and current) probes or sensors are less common. A directional coupler measures the forward and reflected power at the matched input. A phase / magnitude detector monitors the impedance magnitude and phase of the chamber in addition to the match network. Data from the input sensor is sent to a controller where an algorithm is used to adjust the variable capacitor value to minimize the reflected RF power in the case of a directional coupler, or For the phase / magnitude detector, an algorithm is used to bring the impedance magnitude and phase to 50 ohms and zero degrees respectively. This works well for relatively simple, continuous RF processing. For more complex semiconductor manufacturing processes, where RF power is pulsed and radio frequencies are dynamic, more sophisticated sensors such as VI probes are placed at both the input and output sides of the matching network. is necessary. Advanced VI probes monitor the magnitude of RF voltages and currents (and their harmonics) and the phase shift between them. Therefore, their VI probes can accurately measure the complex impedance at both matched 50 ohms (input side) and non-50 ohms (output side) during pulse output and in the presence of dynamic frequency adjustment. can be done.

[0006] An advantage of having an accurate output sensor in the matching network is the ability to directly measure the chamber impedance. This provides additional data points that allow faster impedance matching. This reduces the dependence on preset capacitor positions, where the capacitor needs to be close to the matching point so that it does not "disappear" during tuning. A controller used within a typical matching network executes a control algorithm. The control algorithm is proprietary to the matching network manufacturer and is not user configurable. This may limit the adaptability of matching networks to new processes, which is one of the key requirements of smart manufacturing processes (discussed in more detail below). Therefore, smart matching network controllers used in combination with accurate input and output VI probes are highly desirable.

[0007] As nanotechnology devices shrink in size and / or become more complex, the processes used to fabricate those devices are also becoming more complex. In particular, the design of semiconductor integrated circuits has become democratized, and many technology giants prefer to design their own devices to meet their very unique and unique needs. However, such democratization of semiconductor manufacturing has not been achieved due to the great cost and complexity involved. This has forced semiconductor device manufacturers to make their production lines smarter in order to be able to handle a wider variety of semiconductor devices to be manufactured. Smart sensors, such as input and output VI probes in matching networks, are key to smarter, more adaptive manufacturing processes.

[0008] Smart manufacturing is often defined as highly adaptable computer-integrated manufacturing that allows rapid changes to the manufacturing process. Smart manufacturing relies on smart sensors that automatically collect and analyze data and smart controllers that make intelligent decisions to optimize manufacturing machine performance based on smart sensor data. Data from sensors and machines are often communicated to the cloud or factory network using industrial IoT (Internet of Things) connectivity solutions employed at the factory level. Industrial IoT technology allows data to flow through the factory, providing the ability to remotely monitor and manage processes, thus allowing rapid real-time changes to production schedules as needed. become.

[0009] One of the key considerations in smart factories is the amount of data generated by smart sensors and machines. Edge analytics is used to describe data collection and analytical computations performed on or near smart sensors rather than waiting for data to be returned to a centralized database. terminology. By running the data through analytical algorithms at the source, i.e. at the edge of the factory network, companies can determine which information is worth keeping in a database for later use, and which data can be discarded. It becomes possible to set parameters for Analyzing data as it is generated can also reduce latency in the decision-making process. For example, when input and output sensor data from a matching network are analyzed by a local controller, rules built into the analysis algorithms for interpreting the data at the edge of the network automatically adjust variable capacitors to optimal positions. can do. The reduced data set can then be sent to a centralized location for storage. Algorithmic rules can be modified quickly across the factory network, which has speed requirements lower than the actual data processing speed.

[0010] An important aspect of smart factory implementation is the speed, reliability and eligibility of network connections. Factory automation control systems are, by definition, "real-time systems." Machine control often requires very low latency. Messages traversing the network should have a priority attached to them, eg emergency stop messages should not be delayed by bulk data backup streams. Real-time messages should be prioritized. Traditional Ethernet networks have no protocol for prioritization and treat all data equally. Despite being cheap and fast, Ethernet is not easy to adapt to interconnect control systems. The problem mainly lies in the determinism or time accuracy required for real-time control.

[0011] Therefore, what is needed is a controller for the alignment unit that addresses the shortcomings of the prior art. [Outline of the invention] [Means for solving the problem]

[0012] SUMMARY OF THE INVENTION The present teachings relate to a controller for a matching unit of a plasma processing system, the controller receiving impedance data for an RF generator of the system (measured from the RF generator side of the system) from the matching unit and receiving impedance data from the matching unit to the system RF generator. , process the impedance data using an algorithm that determines the target impedance of the matching unit to match the impedance of the chamber to the impedance of the generator, and the impedance data of the matching unit to achieve the target impedance. adjusting the capacitance of the variable capacitor, the controller acting as a master controller for the matching unit when communicating with the matching unit and a slave controller for the matching unit when communicating with the master controller of the plasma processing system; It is further configured to simultaneously function as a

[0013] The controller may be further configured to communicate with the alignment and plasma processing system over a network based on at least one network protocol.

[0014] Optionally, receiving and processing the impedance data and adjusting the capacitance is performed for each step of the multi-step plasma process, and the controller receives the algorithm during each step of the plasma process and performs subsequent steps of the plasma process. is configured to use the received algorithm for the steps of .

[0015] Optionally, the controller receives an algorithm over the network during any of the impedance data reception and processing and the capacitance adjustment, and stores the received algorithm for later use. , further comprising:

[0016] The controller is further configured to receive an algorithm from a master controller of the plasma processing system while acting as a slave controller for the matching unit and while simultaneously acting as a master controller for the matching unit. Sometimes.

[0017] The controller may be further configured to store a high resolution map of the impedance matching range, which is used to find the target impedance based on the impedance data from the output sensor.

[0018] The controller is further configured to process the impedance data for the chambers of the system, find the conjugate impedance on the high resolution map using an algorithm, and adjust the capacitance of the variable capacitor to achieve the conjugate impedance. Sometimes.

[0019] The controller may be further configured to apply a fine tuning step after the capacitor has been adjusted to achieve the conjugate impedance, the fine tuning step further adjusting the capacitance of the capacitor to provide power. maximize

[0020] Impedance data for the RF generator of the system may be received from an input sensor of the matching unit.

[0021] Optionally, the input sensors monitor the magnitude of RF voltages and currents and their harmonics and the phase shift therebetween.

[0022] Impedance data for the chambers of the system may be received from the output sensor of the matching unit.

[0023] Optionally, input and output sensors monitor the magnitude of RF voltages and currents and their harmonics and the phase shift therebetween.

[0024] The controller may be further configured to interface with the computer via a communication port separate from the interface used to communicate with the plasma processing system.

[0025] Optionally, the controller is further configured to receive an algorithm via the interface, store the received algorithm, and use the algorithm to determine the target impedance.

[0026] The present teachings also relate to an alignment unit comprising a controller as outlined above.

[0027] Brief description of the drawing The invention will be further explained by the following description of an embodiment of the invention given by way of example only, with reference to the accompanying drawings. [Brief description of the drawing]

[0028]

Figure 1

Figure 2

[0029] detailed description According to the invention, a controller 100 is provided for controlling a radio frequency matching network (unit) 101, hereinafter called matching controller. In one embodiment, the matching controller is located inside the matching network enclosure.

[0030] Coherence controller 100 according to the present teachings relies on the use of standardized communication protocols. EtherCAT has proven to be suitable. This protocol was developed by Beckhoff Automation, a leading manufacturer of PLCs (Programmable Logic Controllers) used in industrial automated and real-time control systems. EtherCAT is a real-time industrial Ethernet technology. The EtherCAT protocol is suitable for real-time applications in industrial automation. Two focuses in the development of EtherCAT were short cycle times (or latency) of less than 100 µs and low jitter for accurate synchronization of less than 1 µs. The semiconductor industry has adopted EtherCAT as an automation standard, and EtherCAT device profiles and standards are available today for semiconductor industry specific devices, including RF generators and matching networks.

[0031] An EtherCAT "master" sends messages through each device or node on the EtherCAT network. Each EtherCAT "slave" device on the network reads data addressed to it and inserts its data into the message frame. The last node detects an open port and uses full duplex to send the message back to the EtherCAT master. An EtherCAT master is the only node that can autonomously send EtherCAT frames. All other nodes (slaves) simply forward the frame downstream, thereby preventing unpredictable delays and ensuring real-time functionality. This complicates the EtherCAT-based matching controller 100 . If the input sensor 102, output sensor 103, and variable capacitor 104 all use the EtherCAT protocol, the local matching network controller 100 should act as an EtherCAT master device for these sensors and capacitors. However, a plasma processing machine (of which the matching network is part) will likely have an EtherCAT master controller for controlling all EtherCAT devices on the machine, including the matching unit 101 . Due to the EtherCAT architecture there cannot be two masters.

[0032] Matching controller 100 according to the present teachings functions as an EtherCAT master device 105 in reading data from RF sensors 102, 103 and using said data to control variable capacitor 104 or interlock switches. The matching controller 100 functions as an EtherCAT slave device 106 for communicating with the EtherCAT master controller 107 of the plasma processing machine. For many reasons, it is better to have the matching controller 100 located in / near the matching network 101 than to control the functionality of the matching network 101 remotely, eg from a factory network.

[0033] The placement of the matching controller 100 within this matching network enclosure, within the EtherCAT master mode 105, allows the matching controller 100 to run at speeds independent of the factory network. This can achieve lower latency when operating at the edge of the factory network close to where the sensor data is generated. Intelligent algorithms can be employed in the matching controller CPU 108 to change the algorithms on-the-fly via EtherCAT or via other protocols provided. The data from the sensors 102, 103 are passed through intelligent analysis algorithms to make quick decisions about the plasma impedance and change the position of the capacitor 104 accordingly to optimize match performance. The match controller 100 can receive algorithms during plasma processing steps while reading data from the RF sensors 102, 103 and using the data to control the variable capacitors. The received algorithms can be used during subsequent steps of the same plasma process or during different plasma processes. Receipt and processing of impedance data and tuning of capacitors are performed continuously on the millisecond time scale. Adjustment is therefore a continuous process within each processing step. New algorithms can be sent / received at any time and used within existing steps or in subsequent or later steps. The control system is scalable to handle multiple sensors and devices, such as capacitors and interlock switches, as required.

[0034] FIG. 2 illustrates how matching controller 100 exhibits simultaneous master and slave functionality, enabling a multi-level control architecture. As previously mentioned, the plasma processing machine has a master controller for controlling all (slave) devices 201 on the machine, including the matching unit 101 . Slave device 202 may be the previously mentioned RF sensors 102 , 103 , variable capacitor 104 , or other slave device of matching unit 101 .

[0035] An important feature of the present invention is the ability of the end user to access and change the algorithms of controller 100 . While using the first algorithm for the first step of the plasma processing steps, the matching controller 100 can receive the second algorithm and use it for the second (or later) step of plasma processing. can. Existing matching networks do not have this capability, and only the matching network vendor's engineering team can change the matching algorithm. This is a key feature of plasma process development, where rapid prototyping and testing of novel RF matching schemes can significantly reduce process development time for plasma processing equipment manufacturers.

[0036] In one embodiment, the RF impedance matching network (unit) is a dual frequency matching network integrated with a configurable, self-tuning matching controller. A plasma machine (or tool) host computer communicates with the matching controller via an EtherCAT network. It should be noted that this matching controller is not limited to EtherCAT connections and it will be apparent to those skilled in the art that any of a number of other protocols can be used with minor modifications. sea ​​bream. Some suitable alternative protocols are outlined in the table below. It should also be appreciated that a mix of protocols can be used, as the motor (of the capacitor 104) requires very little data while the sensor requires a large bandwidth. Regardless of which protocol is chosen, controller 100 can be treated as slave device 106 to plasma tool master controller 107 .

[0037]

table 1

[0038] Dual frequency matching networks are commonly used in industry, where two radio frequencies (from two independent RF sources) are fed into two matching networks, followed by a single frequency at the output. coupled to the line. For this topology, the controller has access to two input sensors 102 (to measure the impedance at each frequency at the input) and one output sensor 103 to measure the combined dual frequency output impedance. do. The matching network may have four or more motorized tuning capacitors 104, which also communicate directly with the matching controller. In one configuration, the matching controller 100 is an EtherCAT master device 105, which communicates with input sensors 102 and output sensors 103 (VI sensors) to read RF data, including RF impedance at each drive frequency; The RF data above is used to calculate the optimum capacitor 104 location. In response, the position of capacitor 104 is moved using motor interface protocol 109 .

[0039] FIG. 1 illustrates one embodiment of an RF match controller design according to the present teachings. In this exemplary embodiment, the matching controller 100 is inside the wall of the matching network (unit) 101 enclosure. The matching controller 100 can also be placed near the matching network rather than inside the enclosure. Other hardware devices placed inside the matching network 101 include an RF input sensor 102, an RF output sensor 103, a motorized capacitor 104, a status LED 110, a dc bias (Vdc) sensor 111, a temperature sensor 112, and an interlock. A switch 113 is included. The RF match controller housing houses the computer or microcomputer 108 and its interface connectors.

[0040] In a preferred embodiment, the information hub is a Redis database 114, shared memory mutable storage that can be accessed by all applications. Redis (Remote Dictionary Server) is an in-memory data structure storage mechanism that supports different kinds of abstract data structures such as strings, lists, maps, sets, etc., and is an open source software suitable for this application. However, there are many other options available.

[0041] EtherCAT slave application 106 includes an EtherCAT software stack that provides the application side of the EtherCAT protocol. The EtherCAT slave application 106 responds to EtherCAT slave controller (ESC) requests, updates memory state, and responds to CoE (CAN over EtherCAT), FoE (File over EtherCAT), and other EtherCAT service requests. The slave application 106 converts the information stored in Redis into a format suitable for EtherCAT and updates Redis with the new configuration passed from the plasma tool EtherCAT master 107 .

[0042] EtherCAT master application 105 controls the local EtherCAT network. EtherCAT master application 105 initializes RF sensors 102, 103 and updates Redis 114 with sensor measurements and current motor position (variable capacitor settings). Any change in the calculated target motor position triggers a change in motor destination via the motor interface protocol 109 .

[0043] The Match Autotuning Application 115 reads sensor and motor position information from Redis 114 and, when in autotuning mode, updates the target position (corresponding to the target impedance) according to the selected autotuning algorithm. As outlined above, this algorithm is user customizable and can be updated on-the-fly as needed. This update can be done via the Python development platform. That is, the slave device 106 can receive the python algorithm 116 to update the auto-tuning algorithm. This is an advantageous feature that can enable rapid prototyping of alignment units. Python is an interpreted, object-oriented, high-level programming language with dynamic semantics. Python's built-in data structures make it a very attractive tool for rapid application development. Python is a convenient scripting language often used to wire existing components together. A Python interpreter with rich libraries is freely available and freely distributable for all major platforms. Other scripting platforms can be used as alternatives to Python.

[0044] Pulsed RF power drives many advanced plasma processes, providing access to plasma chemistry not accessible to those driven by continuous wave RF power. . Some treatments may last over an hour and may involve multiple sequential treatment steps. These steps progress from one step to the next without a break in between. Each step is carefully designed to step the function in progress towards completion. Therefore, each step involves some change in process conditions. Pulsed power schemes can be complex, and multi-level pulsing provides better functional control. Changing the pulse profile may involve changing the number of pulse levels and / or the duration of each level. The repetition frequency of the overall pulse profile may also be changed. The matching controller and matching network are expected to perform optimally throughout the various steps to consistently and reliably achieve maximum power delivery to the process. For the types of pulsed RF power schemes already considered, this will almost certainly require a different matching adjustment algorithm at each processing step.

[0045] With the move towards smart manufacturing, there may not be a guarantee that processing steps will occur in the same order each time, and a wider range of products are expected to flow down the manufacturing line in the future. For these reasons, there is a need to re-evaluate the known paradigm of establishing alignment unit adjustment algorithms prior to the introduction of processing tools. A shift to a new paradigm in which the master controller of the processing machine could direct the smart matching network in real time to control the adjustment algorithm would be highly desirable.

[0046] The matching network architecture shown in Figure 1 is designed so that all matching hardware data is accessible from the factory EtherCAT network. The match controller can be installed locally within the match box, as shown, or it can be located entirely within the plasma tool master controller. Controller accessibility enabled by network connectivity allows Plasma Tool Master Controller to change tuning algorithms on-the-fly using FoE (file over EtherCat) or alternative protocols Become. As previously mentioned, this involves the matching controller receiving algorithms over the network while either receiving and processing impedance data and adjusting capacitors. Received algorithms may be saved and used in subsequent steps of the same plasma process, subsequent steps of the same process, or any step of a different plasma process. This is essential for multi-step processing, where the adjustment algorithm can be changed quickly and seamlessly as the processing steps move from one step to the next. If the order of steps can change from time to time, the plasma tool master can choose from a library of algorithms to update the matching controller in real time.

[0047] Other inputs to the controller include an EtherCAT address selector, an interlock switch, an internal temperature sensor, and a DC voltage sensor. Outputs from the controller include status LEDs, RUN and ERR LEDs for the external EthercAT network. These inputs interface with the application 117 running on the CPU 108 of the controller 100 and the data is stored in Redis memory.

[0048] Access to the controller is also available via USB and / or RS232 118. If the matching controller is not on the EtherCAT network, the PC user interface can be used to configure the matching controller. This is important during off-line testing and calibration when the controller (or matching network / unit with the controller inside) is not attached to the plasma processing tool / system. It will be appreciated that other interfaces or ports than USB and RS232 may be used.

[0049] A typical (prior art) self-tuning matching network has presets configured for capacitor positions. These are established during the process development stage. The positions (or values) of the capacitors are established and stored in memory for standard processing runs. Thermally induced drift due to process drift, component degradation due to aging, and power dissipated in the components of the matching unit cause changes in the optimal capacitor position. A fine tuning algorithm monitors drift in the power supply and adjusts capacitor positions to compensate. Preset positions are not required for the devices described herein. A high resolution map of the impedance matching range can be saved to a Redis memory location. An output sensor (VI probe) accurately measures the process impedance. As a coarse tuning step, the algorithm finds the conjugate or corresponding impedance on the map and directs the capacitor to move directly to this impedance location. A fine tuning step is then applied to fine tune the capacitor position to maximize the power delivery as reported by the input sensor. This method allows fast adjustment of the matching unit when there is a change in the process impedance.

[0050] Note the following key features of the invention described herein: ● Local controllers can run at speeds independent of the factory master Able to run local intelligent algorithms ● Provides lower data latency on the network edge Allows for customizable control algorithms that can be updated on the fly ●Simultaneous operation of controller master and slave The control system is scalable and can seamlessly integrate multiple sensors / capacitors ● Can be Linux-based EtherCAT master / slave station control system and method.

[0051] Note that the communication within the matching network between the various hardware elements, including the sensors and motors, is typically ad-hoc. A sensor may use a local interface such as SPI or UART. The motor may be voltage level controlled and / or speed controlled or stepped using TTL signals or a local controller using UART / RS485. Using standardized industrial network protocols means that components such as motors and sensors are compatible, allowing manufacturers to vertically integrate matching units into their tools.

[0052] As will be apparent to those skilled in the art, EtherCAT networks generally have a single master and multiple slave devices. The present teachings result in a local master controller that behaves like a slave device when communicating with higher masters on the network. Thus, the controller acts as master and slave at the same time. This enables the control architecture shown in Figure 2, extending the well-known master / slave architecture to a new master / slave-master / slave architecture.

[0053] Another novel implementation of the matching unit control architecture is to integrate the controller 100 modules into the plasma tool master controller to create a fully remotely controlled matching network. Therefore, a matching unit without the first local controller is created. As mentioned above, the only drawback is that the speed is limited by the speed of the factory network. As network speed and reliability improve, especially with the deployment of 5G for future smart factories, full remote control of matching networks will become more attractive.

[0054] The apparatus provided in the current teachings comprises a matching unit controller that operates in combination with one or more RF input sensors and one or more RF output sensors. This controller has the EtherCAT Master Controller application and acts as the local EtherCAT master in the matching unit. The controller collects data from input and output sensors and feeds the data to intelligent algorithms. The output from the algorithm is used to set the positions of the matching unit capacitors. The controller also has an EtherCAT slave controller application for communicating with the master controller of the plasma processing machine.

[0055] Described herein is a controller that allows the user full control over how the alignment unit operates. Users can purchase a metal box, add off-the-shelf variable capacitors, inductors, sensors, etc., as well as the matching unit controller (and sensors) described herein, and easily tailor the matching unit to their own specifications. Can be customized. You can also add smart algorithms to them. This enables rapid prototyping and faster process development.

[0056] A step motor allows the capacitance of the variable capacitor to be precisely adjusted.

[0057] The word "comprises / comprising", as used herein, is intended to indicate the presence of a recited feature, integer, step, or component, but one or It does not exclude the presence or addition of multiple other features, integers, steps, components or groups thereof. [Description of symbols]

[0058] 100 matching controller 101 matching unit 102 Input sensor 103 Output sensor 104 variable capacitor 105 EtherCAT Master Application 106 EtherCAT Slave Applications 107 EtherCAT Master Controller 108 matching controller CPU 109 Motor Interface Protocol 110 status LEDs 111 dc bias (Vdc) sensor 112 temperature sensor 113 Interlock Switch 114 Redis database 115 Match Auto Adjust Application 116 python algorithm 117 applications 118 USB and / or RS232 201, 202 slave device

Claims

1. 1. A controller for a matching unit of a plasma processing system, comprising: receiving impedance data seen from the RF generator side of the system from the matching unit; receiving impedance data for a chamber of the system from the matching unit; processing the impedance data using an algorithm to determine a target impedance for the matching unit to match the impedance of the chamber to the impedance of the generator; and adjusting a capacitance of a variable capacitor of the matching unit to achieve the target impedance. The controller simultaneously: acting as a master controller for said alignment unit when communicating with said alignment unit; The controller is further configured to act as a slave controller for the matching unit when in communication with a master controller of the plasma processing system.

2. The controller of claim 1 , wherein the controller is further configured to communicate with the matching unit and the master controller of the plasma processing system over a network based on at least one network protocol.

3. 3. The controller of claim 2, wherein the controller is further configured to receive an algorithm over the network during any of the receiving and processing of the impedance data and the adjusting of the capacitance, and to store the received algorithm for later use.

4. 4. The controller of claim 3, wherein the receiving and processing of the impedance data and the adjusting of the capacitance are performed for each step of a multi-step plasma process, and the controller is configured to receive an algorithm during each step of the plasma process and use the received algorithm for subsequent steps of the plasma process.

5. 5. The controller of claim 3 or 4, further configured to receive an algorithm from the master controller of the plasma processing system while functioning as the slave controller of the matching unit and simultaneously while functioning as the master controller for the matching unit.

6. 5. The controller of claim 1, further configured to store a high resolution map of impedance matching ranges, the map being used to find the target impedance based on the impedance data from the output sensor.

7. 7. The controller of claim 6, wherein the controller is further configured to process the impedance data for the chamber of the system, use the algorithm to find a conjugate impedance on the high resolution map, and adjust the capacitance of the variable capacitor to achieve the conjugate impedance.

8. 8. The controller of claim 7, wherein the controller is further configured to apply a fine-tuning step after the capacitor is adjusted to achieve the conjugate impedance, the fine-tuning step further adjusting the capacitance of the capacitor to maximize power delivery.

9. A controller according to any preceding claim, wherein the impedance data for an RF generator of the system is received from an input sensor of the matching unit.

10. The controller of claim 9 , wherein the input sensors monitor the magnitude of RF voltage and current and their harmonics and the phase shift between them.

11. The controller of any one of claims 1 to 4, wherein the impedance data for a chamber of the system is received from an output sensor of the matching unit.

12. The controller of claim 11 , wherein the output sensor monitors the magnitude of RF voltage and current and their harmonics and the phase shift between them.

13. The controller of any one of claims 1 to 4, wherein the controller is further configured to interface with a computer via a communications port separate from an interface used to communicate with the plasma processing system.

14. The controller of claim 13 , wherein the controller is further configured to receive an algorithm via the interface, store the received algorithm, and use the algorithm to determine the target impedance.

15. An alignment unit comprising a controller according to any one of claims 1 to 4.

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