Design of Automatic Matching System for Very High Frequency Plasma-Enhanced Processes

Since it can change electron energy distribution functions, very high frequency (VHF) plasma has gained significant attention as a promising new class of plasma. We demonstrate an automatic matching system for VHF plasma, that works in very wide ranges. A matching system was prepared using conventional variable capacitors. Reflection coefficient at the input of the matching circuits was measured with a directional coupler. A new calculation method for automatic matching based on numerical models for the circuit was developed, and the performance of the automatic matching system was evaluated using a load emulator. These results revealed that the system has an automatic matching capability for the entire range of the covering load area.