| 摘要 |
A strike enhancement circuit for a dc power supply, which can be a switched half-bridge supply (12, Fig 1), creates a high voltage at high impedance to initiate a plasma in a plasma chamber or sputtering chamber. The strike enhancement circuit 38 has a plurality of diode bridges 44, 46, 48, 50 that act as full-wave rectifiers or peak detectors. A transformer secondary of the power supply (12) is connected through isolation capacitors 52, 54, 56, 68 to the ac inputs of each of the diode bridges. The dc ports +, - of the diode bridges 44, 46, 48, 50 are stacked in series, and the combined, stacked voltage is applied across the input terminals of the plasma chamber. Each diode bridge also has a storage capacitor 68, 70, 72, 74 connected between the positive and negative dc ports. Positive and negative voltage peaks from the transformer secondary waveform are stored in the storage capacitors. The combined dc outputs applied to the plasma chamber appear as a voltage high enough to initiate a plasma discharge. Once the plasma is present, the impedance of the isolation capacitors 52, 54, 56, 58 and the storage capacitors 60, 62, 64, 66 prevents the strike circuit from providing the high strike voltage.
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