Capacitively coupled plasma
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A capacitively coupled plasma (CCP) is one of the most common types of industrial plasma reactors. It essentially consists of a two metal electrodes separated by a small distance, placed in a reactor. The reactor pressure can be lower than atmosphere or it can be atmospheric.
One of these two electrodes is connected to a power supply, and the other one is grounded. As this configuration is similar in principle to a capacitor in an electric circuit, the plasma is called a capacitively coupled plasma.
When time-varying electric field is applied to the powered electrode, electrons in the gas respond to the field and acquire energy. Ions or gas molecules, being heavier, do not acquire energy from the oscillating electric fields. They instead get their energy from the energetic (hot) electrons.
This leads to what is known as "breakdown". After breakdown, the gas becomes electrically conductive. In normal cases, it also starts emitting light and thus a visible plasma is seen.
CCPs have wide applications in the semiconductor processing industry for thin film deposition.
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