The AE VarioMatch™ Match Network, VM 1000/1500 Platform, is a sophisticated device designed for rapid, accurate, and reliable impedance matching in various industrial applications, primarily those involving plasma chambers or CO2-laser systems. Its core function is to transform the impedance of a load to 50 Ω, ensuring that the connected RF power generator delivers its full power to the load without significant reflected power.
Function Description:
The VarioMatch match network operates by adjusting its internal components to achieve optimal impedance matching. Most VarioMatch match networks utilize a basic L-type match topology, which allows for a very wide tuning range. Some models, particularly ICP (Inductively Coupled Plasma) units, may also employ a Gamma topology, which is advantageous for matching very low impedances. The network is optimized for capacitively coupled plasma and CO2-laser loads, demonstrating excellent capability in matching even low impedances (real part). Typical applications include CVD (Chemical Vapor Deposition), PVD (Physical Vapor Deposition), sputtering, RIE (Reactive Ion Etching), and CO2-laser excitation. Specific ICP options are tailored for inductive loads.
The device employs vacuum variable capacitors for tuning, which enhances resistance to high voltage breakdown (a common issue with air gap capacitors) and provides a large RF current carrying capability, up to 67 A. These capacitors offer fine tuning resolution, contributing to faster and more accurate matching, and ultimately, lower reflected power levels. The matching process is achieved through phase and magnitude detection, which is faster than traditional trial-and-error methods. The network can typically achieve a matched condition within 0.5 to 5 seconds from the start of tuning, and it accurately and reliably tunes with RF levels as low as 1% of the maximum transfer power.
VarioMatch match networks are designed to withstand the demanding conditions of low resistance plasma loads and their associated high RF currents. All internal components and connections are engineered to handle very large RF currents and high current pulses. A DC bias measurement circuit, available on most units, monitors the DC self-bias voltage created in the load. This voltage is scaled down by a factor of 1:400 to a safe and convenient value, always presenting a positive DC bias test voltage regardless of the actual chamber voltage. The units are self-contained, requiring only an AC MAINS connection for operation. When used with an AE RF generator, manual controls are integrated into the generator itself, eliminating the need for an additional controller unless manual operation without an AE RF generator is desired.
Important Technical Specifications:
The VarioMatch match network comes in various series (VM 300, VM 700, VM 1000, VM 1500), each with specific electrical and physical characteristics.
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Physical Specifications:
- Dimensions: 375 mm x 245 mm x 150 mm (14.75" x 5.9" x 9.65").
- Weight: 6.5 kg (14.3 lb).
- Mounting: Directly onto the load or a mounting plate.
- Connectors:
- Match INTERFACE: 15-pin subminiature-D female.
- RF-GENERATOR input: 50 Ω N-type.
- PLASMA/LOAD connector: Varies by product PN, including 6 mm brass tube fittings, 7/16 DIN socket, M6 bolt, or MC B6N (female 6 mm).
- AC power input (AC-MAINS): IEC 320 connector.
- Coolant connectors: Brass water fittings for 6 mm OD / 4 mm ID (0.24" OD / 0.16" ID) tubing for water-cooled units.
- Internal Coil Specifications: Tune coils vary by part number, turns (e.g., 2.5, 6, 10, 14, 25, 26.5 turns), and tap settings. Load coils also vary, with some having 2 or 4 turns with multiple taps, while others have no load coil.
- Topology: Primarily L match, with some ICP units supporting Gamma or a choice between L match and Gamma.
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Electrical Specifications (General for VM 300, 700, 1000, 1500 Series):
- Frequency: Typically 13.56 MHz, but can vary for VM 1500 series (e.g., 2.00 MHz, 4.00 MHz, 27.12 MHz, 40.68 MHz).
- AC line voltage: 100 VAC to 240 VAC, single phase.
- AC line frequency: 50 Hz to 60 Hz.
- AC line current (maximum): 1.0 A to 0.7 A.
- Maximum transfer power: 300 W (VM 300), 700 W (VM 700), 1000 W (VM 1000), 1500 W (VM 1500).
- Maximum reactive power: Varies by product PN, e.g., 88,000 W, 100,000 W, 140,000 W, 220,000 W.
- Maximum RF load current: Varies by product PN, e.g., 15 A, 20 A, 22 A, 25 A, 35 A, 55 A.
- Maximum RF load voltage: 4000 Vpeak.
- Input impedance to generator: 50 Ω.
- Maximum load DC self-bias voltage: 0 VDC to 10 VDC (monitor voltage), 0 VDC to 4000 VDC (actual).
- Runtime from start point to end point: 3 seconds.
- Tuning range: Adjustable by changing load and/or tune coil settings.
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Cooling Specifications:
- Cooling medium: Air-cooled or Air- and Water-cooled (indicated by "A" or "W/AW" in model number).
- Minimum water flow (for water-cooled units): 1 lpm (0.26 gpm).
- Water pressure: 0.5 bar (7.25 psi) differential (minimum), 4 bar (58 psi) (maximum inlet, not recommended for operation).
- Cooling water temperature: 20°C to 35°C (must be higher than ambient to avoid condensation).
- Water Contaminants: pH between 7 and 9, total chlorine <20 ppm, total nitrate <10 ppm, total sulfate <100 ppm, total dissolved solids <250 ppm, total hardness (calcium carbonate equivalent) maximum 250 ppm, specific resistivity of 2500 Ω/cm or higher at 25°C. De-ionized water is not recommended due to corrosion and erosion.
- Minimum air flow (for air-cooled units): 120 m³/h.
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Environmental Specifications (per EN50178):
- Operating Temperature: +5°C to +40°C (+41°F to 104°F).
- Storage Temperature: -25°C to +55°C (-13°F to +131°F).
- Transportation Temperature: -25°C to +70°C (-13°F to +158°F).
- Relative Humidity: 5% to 85% (non-condensing, no ice formation) for operating, 5% to 95% for storage.
- Air Pressure: 78 kPa to 106 kPa (788 mbar to 1060 mbar) for operating and storage.
- Overvoltage Category: II.
- Pollution Degree: 2 (indoor location, nonconductive pollution, temporary conductivity from condensation when not operating).
Usage Features:
The VarioMatch match network offers both automatic and manual tune modes.
- Automatic Tune Mode: Recommended for standard operation. The unit automatically measures amplitude and phase via fast analog control signals and drives the capacitors to transform the impedance to the generator's required impedance. This mode requires no user interface. A minimum RF input power (approximately 1% of maximum transfer power) is necessary for proper operation of the automatic detection and control circuitry.
- Manual Tune Mode: Disables automatic tuning, allowing capacitor positions to be controlled via the 15-pin INTERFACE port. This mode is useful for unknown loads or when fine-tuning is required, especially if automatic matching is not optimal (e.g., capacitors outside the 20-80% tuning range). Manual control can be achieved through an external controller like the AE RMC-1, an AE Cesar RF Generator, or a simple arrangement of five switches.
Maintenance Features:
- Installation and Setup: Detailed instructions are provided for preparing the unit, including spacing requirements, tools needed, unpacking, cable requirements (emphasizing short, shielded, low-inductance RF cabling for minimal losses and EMI reduction), and proper grounding.
- Mounting: The unit should be mounted as close as possible to the load, ensuring adequate space for connections and top panel access. It should not be mounted on hot tools to prevent overheating. The cooling fan should face up.
- Coil Tap Settings: The tune and load coils have multiple tap settings to adjust the match range for different load impedances. Instructions are provided for changing these tap settings by removing the top cover and adjusting the threaded bar and bolts on the coil.
- Fixed Capacitor Settings (Model 0415 2 MHz Units Only): For specific models, additional fixed capacitors can be switched in parallel to the load capacitor to increase capacitance. This involves removing the front panel and carefully adjusting jumpers on the circuit board.
- Topology Configuration (for some ICP units): Certain ICP units allow switching between L match and Gamma topologies by changing the capacitor's interconnection. This involves disconnecting power, removing covers, and adjusting interconnector and jumper settings.
- Cooling System Maintenance: For water-cooled units, specific guidelines for water quality (pH, contaminants, flow, pressure, temperature) are provided to prevent corrosion and erosion. Instructions for disconnecting water and draining the unit are included for maintenance, moving, or storage, emphasizing the importance of purging all water to prevent damage from freezing.
- Troubleshooting: The manual includes checklists for troubleshooting with power off and power on, as well as advanced troubleshooting for unit output issues (e.g., external load checks for open/short RF output path).
- Global Services: Contact information for AE Global Services is provided for technical support and returning units for repair, including phone, fax, and email. Customers are advised to have the unit's serial and part numbers ready.
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