Quantification of VUV photon and particle fluxes in low pressure plasmas for surface treatment

用于表面处理的低压等离子体中的紫外（UV），特别是真空紫外光谱范围（VUV）中的光子通量可以对材料表面产生决定性影响。能量分辨量化和必要时对这些通量的调整是优化各自等离子体过程的基础。因此，需要应用VUV光谱仪，它需要直接进入等离子体室，并且需要在现场进行复杂的强度校准。因此，到目前为止，基础研究只存在于非常具体的应用或仅限于模拟。本项目旨在对用于表面处理的等离子体中的UV和VUV光子通量及其与发生的粒子通量的相关性进行系统的波长分辨量化。第二步将开发一种便携式测量装置，以便获得过程等离子体的相关VUV/UV光子通量。研究是在一个专门的实验室实验中进行的，该实验室配备了用于通量表征的适当诊断：从VUV到近红外光谱范围的强度校准发射光谱，可移动的Langmuir探针以及能量分辨质谱。为了确定影响等离子体发射辐射的主要等离子体参数，这些测量得到了包括等离子体内光子重吸收效应在内的碰撞辐射模型的辅助。与此同时，将开发一种紧凑的测量装置的原型，用于量化过程等离子体中能量分辨的VUV/UV光子通量。该仪器基于一个VUV敏感光电二极管和可互换的过滤器，可根据特定的工艺气体进行选择。实验室设置提供了一个独特的机会，可以对绝对校准的VUV光谱仪进行基准测试。为了证明其处理等离子体的适用性，该装置将在三个与表面处理相关的不同实验中进行最终测试。

Photon fluxes in the ultraviolet (UV) and in particular in the vacuum-ultraviolet spectral range (VUV) within low pressure plasmas for surface treatment can have a decisive impact on the material's surface. Energy resolved quantification and if necessary tuning of these fluxes is elementary for optimizing the respective plasma processes. Therefore, VUV spectrometers need to be applied, which require direct access to the plasma chamber and whose complex intensity calibration needs to be performed on-site. Hence, up to now fundamental studies exist only for very specific applications or are limited to simulations. This project aims at the systematic wavelength-resolved quantification of the UV and VUV photon fluxes in plasmas used for surface treatment and their correlation to the occurring particle fluxes. A portable measurement device is to be developed in a second step, in order to make relevant VUV/UV photon fluxes at process plasmas accessible. The investigations are conducted at a dedicated laboratory experiment equipped with the appropriate diagnostics for the flux characterization: intensity calibrated emission spectroscopy from the VUV through to the NIR spectral range, a moveable Langmuir probe as well as energy resolved mass spectrometry. The measurements are assisted by collisional-radiative modelling including the effects of reabsorption of photons within the plasma, in order to determine the main influencing plasma parameters on the emitted radiation. In parallel a prototype for a compact measurement device to quantify energy resolved VUV/UV photon fluxes at process plasmas will be developed. The instrument is based on a VUV sensitive photodiode and interchangeable filters, which are to be selected with regard to the particular process gases. The laboratory setup gives the unique opportunity to benchmark the device against the absolutely calibrated VUV spectrometer. In order to demonstrate its applicability to process plasmas the device will conclusively be tested at three different experiments related to surface treatment.