ALP System Langmuir Probe RF 13.56MHz CCP demo

View the ALP System RF Langmuir PRobe installed in a CCP chamber running 13.56MHz source. Argon plasma, 100sccm.

Category:

Science & Technology

Tags:

• Langmuir Probe
• ALP System

[ImpedansTV]

If this theory is applied correctly to the IV characteristic (as shown in the demo video) very accurate measurements of the plasma properties can be obtained. This is a true for all plasma types - not just CC rf plasma. If you are using your probe in a CC rf plasma you should consider the need for 'rf compensation' of the plasma excitation frequency. We would be happy to share more information on this topic if you have further queries. info@impedans.com

[ImpedansTV]

This demo was performed using a cylindrical probe. A saturated electron current is not possible for this type of probe. When the bias applied to the probe is increased the cylindrical sheath around the probe increases. This necessarily increases the probe collection area as a result. Most theory does indeed account for this using 'sheath expansion' terms.

[ImpedansTV]

In theory a flat 'planar' Langmuir probe shows a saturated electron current. This is due to the assumption that the sheath edge and probe face remain parallel regardless of the potential applied and therefore the effective collection area does not increase. This is not observed in reality since the 'real' sheath often curves into a hemispherical shape above the planar probe (changing as a function of applied potential) and increases the effective area from which ions can be collected bythe probe

[DeverNorMan]

This is the result of an automated probe? Is it typical for the electron current not to saturate in the case of CC RF plasma? I have tried to get a solid Langmuir curve from ours using a probe I put together, but the curve looks like this one (with resistive elements), not like the ones we see in theory.