Mechanisms of ambient-pressure plasma-enhanced chemical vapor deposition – studies of dielectric barrier discharges with short gasresidence times (“FiloSurf”)

等离子体增强化学气相沉积（PECVD）在环境压力下的物理化学机制目前的知识状况相对较差，尽管它在太阳能电池生产、腐蚀保护、玻璃和光学工业涂层或药品粉末涂层等广泛应用方面具有相当大的潜力。一般来说，自由基还是载流子是薄膜形成的主要贡献者，这甚至是一个悬而未决的问题。六甲基二硅氧烷（HMDSO）离子沉积途径的实验证据最近被一个提议者报道。相应的研究利用了氩气- hmdso混合物在单丝介质阻挡放电（SF DBD）中以高速流动的短停留时间。阳离子成膜途径的发现得到了最近的时间和空间相关建模研究的有力支持，该研究是由第二个提议者获得的四甲基硅烷在氩气中的平面平行dbd。本研究的中心思想是利用DBDs气体停留时间短的特性，特别是SF DBDs和等离子片DBDs，在加入少量不同分子气体的氩气混合物中使用DBDs来研究常压PECVD的机制。第三位提案人将强调放电物理学的各个方面：制度、发展和关键物种密度。要研究的外加剂是六甲基二硅烷（HMDS）以及碳氢化合物，如甲烷，乙烷，乙烯和乙烯。三位申请者分别在基于等离子体的表面工程、实验等离子体物理和等离子体建模方面具有长期的专业知识。他们将共同努力，通过实验，特别是激光吸收和光学发射光谱，以及数值模拟，研究受激Ar原子作为电离、解离和激发过程的能量载体的作用。目的是实现第一激发流形Ar(155) - Ar（1s2）的所有四个能级的作用。离子沉积在dbd基PECVD中的作用以及所生长薄膜的组成、结构和性能是薄膜生长实验和模型研究的重点。在这些研究中，将比较正弦和纳米脉冲电压操作。dbd中的小前体周转量也将用于通过光学光谱和稳定产物的气相色谱/质谱分析来验证复杂等离子体化学模型中的初级反应。项目的结果将极大地促进关于基于dbd的PECVD的知识状态。一方面，它们将有助于验证和推进这种混合物中dbd的现有等离子体化学模型。另一方面，它们将对未来的应用具有相当大的实际意义。

The current state of knowledge about physico-chemical mechanisms of plasma-enhanced chemical vapor deposition (PECVD) at ambient pressure is comparatively poor, in spite of its considerable potential for a wide range of applications such as solar-cell production, corrosion protection, coating in glass and optics industries, or for powder coating of pharmaceutical products. In general, it is even an open question, whether radicals or charge carriers are the main contributors to film formation. Experimental evidence of an ionic deposition pathway has recently been reported for hexamethyldisiloxane (HMDSO) by one of the proposers. The corresponding studies took advantage of the short residence time of an argon-HMDSO mixture in a single-filament dielectric barrier discharge (SF DBD) through which the gas flowed with high velocity. The finding of a cationic film-formation pathway is strongly supported by recent time- and space-dependent modeling studies by a second proposer obtained for plane-parallel DBDs in argon with tetramethylsilane. The central idea of the present proposal is to make use of special characteristics of DBDs with short gas-residence times, particularly SF DBDs as well as plasma-sheet DBDs, in order to get new insights into mechanisms of ambient-pressure PECVD using DBDs in mixtures of argon with addition of small amounts of different molecular gases. A third proposer will emphasize aspects of discharge physics: regimes, development and key species densities. The admixtures to be studied are hexamethyldisilane (HMDS) as well as hydrocarbons, such as methane, ethane, ethene, and ethyne. The three applicants have long-term expertise in plasma-based surface engineering, experimental plasma physics, and plasma modeling, respectively. They will join their efforts to study the role of excited Ar atoms as energy carriers for ionization, dissociation, and excitation processes experimentally, in particular laser absorption and optical emission spectroscopy, as well as by numerical modeling. The aim is to carry out the role of all four levels of the first excited manifold Ar(1s5) - Ar(1s2). The role of ionic deposition in DBD-based PECVD as well as of the composition, structure and properties of the films grown are in the focus of the film growth experiments and the modeling studies. For these investigations, sinusoidal and nanopulsed voltage operation will be compared. The small precursor turnover in the DBDs will also be used to validate primary reactions in complex plasma-chemical models by means of optical spectroscopy and gas chromatic/mass spectrometry analysis of stable products. Results of the project will substantially promote the state of knowledge regarding DBD-based PECVD. On the one hand, they will help to validate and advance existing plasma-chemical models of DBDs in such mixtures. On the other hand, they will be of considerable practical relevance for future applications.