Exploring the temporally resolved electron density evolution in extreme ultra-violet induced plasmas

Abstract

We measured the electron density in an Extreme Ultra-Violet (EUV) induced plasma. This is achieved in a low-pressure argon plasma by using a method called microwave cavity resonance spectroscopy. The measured electron density just after the EUV pulse is 2.6 × 10 16 m −3 . This is in good agreement with a theoretical prediction from photo ionization, which yields a density of 4.5 × 10 16 m −3 . After the EUV pulse the density slightly increase due to electron impact ionization. The plasma (i.e. electron density) decays in tens of microseconds.PACS numbers: 52.70.Gw,81.16.Nd Submitted to: J. Phys. D: Appl. Phys.

Exploring the electron density in plasma induced by EUV radiation: II. Numerical studies in argon and hydrogen

“…3 and Fig. 4), yields a ∼ 50% cumulative uncertainty, which is comparable to the ∼30% error margin of of the experiment [3].…”

“…It was shown in [3] that it is possible to measure the electron density of an EUV induced plasma, at relevant background gas pressures, by measuring the resonant frequency shift of a microwave cavity that contains the plasma. Although this is a highly sensitive method, it only allows the field average [4] electron density inside the cavity to be determined.…”

Extreme ultraviolet (EUV) source and ultra-high vacuum chamber for studying EUV-induced processes

“…To study plasma dynamics during the EUV pulse, it is necessary to take into account the emission from the surface of the probe, which we have not yet studied. 0,0 2,0x10 -6 4,0x10 -6 6,0x10 -6 8,0x10 -6 1,0x10 -5 3,2x10 13 3,4x10 13 3,6x10 13 3,8x10 13 Electron density,…”

“…For the study of elementary processes in the EUV-induced plasma, the apparatus must be equipped with the appropriate diagnostics. Recent direct studies of the EUV-induced plasma were successfully carried out by using a method called microwave cavity resonance spectroscopy [13], but in this case, surface processes, such as secondary electron emission and surface plasma formation cannot be studied. However, EUV induced secondary electrons, which escape from the surface of the topmost or capping layer, are able to trigger surface reactions, possibly with an even higher efficiency than direct EUV photoionization.…”

Numerical study of extreme-ultra-violet generated plasmas in hydrogen

“…It was shown in [90] that it is possible to measure the electron density of an EUV induced plasma, at relevant background gas pressures, by measuring the resonant frequency shi of a microwave cavity that contains the plasma. Although this is a highly sensitive method, it only allows the field average [91] electron density inside the cavity to be determined.…”