Plasma probe and method for plasma diagnostics
AssigneeImec
InventorsVLADIMIR SAMARA, JEAN-FRANÇOIS DE MARNEFFE, WERNER BOULLART
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Abstract
Device and method for monitoring a plasma in a chamber of a plasma reactor is are disclosed. In one aspect, the method includes measuring plasma parameter data at a surface of a single planar Langmuir probe in contact with the plasma. A biasing capacitor is connected between the single planar Langmuir probe and a DC-bias source. Subsequently a discharge current of the biasing capacitor as a result of the DC-bias is measured, and a probe potential at the single probe during the discharge is measured. The measurements can be used to detect presence and/or thickness of a dielectric film on the probe surface.
Claims19
A method of monitoring a plasma in a chamber of a plasma reactor, the method comprising measuring plasma parameter data at a surface of a single planar Langmuir probe in contact with the plasma, the plasma parameter data measuring comprising:
- biasing a biasing capacitor connected between the single planar Langmuir probe and a bias source adapted to apply the biasing, wherein the biasing comprises applying a DC-bias;
- and
- subsequently measuring a discharge current of the biasing capacitor as a result of the biasing, and a probe potential at the single probe during the discharge.
A device for monitoring a plasma in a chamber of a plasma reactor, comprising:
- a single planar Langmuir probe inside the chamber having a surface for entering in contact with the plasma;
- a biasing capacitor external to the chamber mounted in series between the single Langmuir probe;
- a bias source for biasing the biasing capacitor;
- and
- a measuring module configured to measure a discharge current of the biasing capacitor as a result of the biasing, and a probe potential at the single probe during the discharge,
- wherein the bias source is a DC-bias source adapted for applying a DC-bias.
A method of measuring in-situ a capacitance of a dielectric film deposited on a surface of a single Langmuir probe which is located inside a chamber of a plasma reactor in contact with a plasma, the method comprising:
- a) alternatingly providing the single Langmuir probe with positive and negative DC-pulses through a biasing capacitor, the positive DC-pulses being suitable for charging the biasing capacitor above a floating potential of the plasma and the negative DC-pulses being suitable for charging the biasing capacitor below a floating potential of the plasma;
- b) measuring a first probe potential during the positive DC-pulses and a second probe potential during the negative DC-pulses;
- c) calculating the difference (ΔV) between the measured first floating potential and the measured second floating potential;
- and
- d) calculating the capacitance of the dielectric film (Cfilm) using the calculated difference (ΔV), the amplitude of the DC-pulses (Va) and the capacitance of the biasing capacitor (Cbias).
Dependencies are inferred from the claim text.