| 摘要 |
A monitor has been developed for measuring charging currents and voltages in a plasma environment. An antenna in the form of a small aluminum pad is connected to ground through a blocking diode, a blocking transistor, and a storage capacitor. The blocking transistor controls the flow of charge to the capacitor, its control gate being activated by a string of photodiodes that are exposed to the plasma. In a second embodiment, the photodiodes are omitted and the gate is connected directly to the antenna. This ensures that the capacitor charges only while the plasma is on. Once the plasma process has been completed, the monitor may be interrogated at leisure by reading the voltage stored on the capacitor. A resistor, connected in parallel with the capacitor, allows current, as well as voltage, measurements to be made. By using either n-channel or p-channel MOSFETs, electron charging or ion charging respectively may be measured. A plurality of such monitors are implemented on a single chip, each monitor using a resistor of a different value. This allows the I-V characteristics of the plasma to be determined.
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