Plasma discharge device, RF cable heating problem

Plasma used for thin film production in vacuum deposition equipment, etching equipment, etc.  And, among the many powers used to generate plasma, the most common 13.56MHz RF power.  We are applying RF power plasma devices in quite a lot of fields such as semiconductors, displays, etc.  RF power plasma devices are more complicated than regular DC plasma devices and require a matching network. However, it can be used in insulators, and the surface properties of thin films are often improved, so RF is often used.  There are many things to consider about these RF discharge plasma devices, but today, I want to write about the heat generation problems that occur in RF cables.  The RF plasma discharge device consists of an RF power supply, an impedance matcher (matching network) for effectively delivering power to the load, and a discharge load device.  RF power requires an understanding of impedance. Impedance is an amount that defines the correlation between voltage and current. In DC, resistance becomes impedance. It becomes complicated in AC power, and when it takes up this and that complex understanding, there are real resistance and imaginary resistance. From the plasma point of view, the real resistance is related to the amount of absorbed power (density and quality of plasma), and the imaginary resistance is the amount independent of power consumption (the amount that is not consumed and reflected) and the supplied energy. You can think of it as saving. The role that is stored in this way is a complicated explanation, and it is most often caused by heat, and we recognize the heating line. Most of the time, there is a problem.  After all, RF power requires impedance matching to reduce this heat generation problem. Being a fever means that there is a problem with matching, and that power transmission is not efficient for the load (power loss).
To reduce power loss, plasma density and quality must be improved. It is necessary to check various process conditions in consideration of discharge characteristics. The next method is to reduce the actual resistance of the line. It is good to minimize each fastening part of the conducting wire and apply coating or silver plating to prevent surface oxidation. Also, the thickness of the line should be considered. If it is difficult to solve the thickness of a line, multiple lines in parallel can be a method. Finally, there is a method to increase the effective real resistance, which can be suppressed by increasing the voltage and decreasing the current. However, if the balance is not balanced, adverse effects will occur, and additional problems such as arcing should be considered.  In some cases, there is a problem caused by the parasitic capacitance, which induces heat generation when matching occurs in the form of shaking or noise. There is a need for a technique to configure the system so that the resonant circuit is not constructed.  If continuous heat generation is not resolved in the delivery of RF power, it is necessary to consider distributing and supplying current. One solution is to reduce the current by configuring transmission lines in parallel.  In the case of ICP, the antennas may be configured in parallel to distribute current.