文献中已经提出了使用气态物质来抵消贵金属在介电基板上的三维生长趋势,并有利于较早的渗滤,而不会损害电性能。在SiO2上磁控溅射沉积Ag膜过程中存在O2的情况下,这种“表面活性剂”效应在本文中是合理的。原位和实时技术(X射线光发射,薄膜电阻率,紫外可见光谱)和非原位表征(X射线衍射和透射电子显微镜)相结合,以仔细检查气流中O2添加的影响(%O2),揭示了薄膜电阻率演变的三个机制,形态学,结构,和化学成分。在低氧流量条件下(%O2<4),观察到的渗滤阈值的急剧降低被分配给(i)纳米粒子密度的变化的组合,润湿,和晶体学织构和(ii)延迟聚结效应。驱动力归因于特定吸附的氧部分的存在,其性质在中间氧气流量条件(10≤%O2<20)下开始演变。在高氧气流量下(20≤%O2<40),所发现的对膜电阻率的有害影响被赋予以Ag2O样结晶不良的化合物形式的实际氧化。对于所有%O2,在膜厚度上观察到组成梯度,在衬底界面处具有更多的金属Ag。观察到渗滤与检测到的O部分的性质之间的相关性。与氧气溢出机制并行,这种梯度可以用渗滤之前发生的不同表面过程之间的竞争来解释,即,聚合,金属氧化,和底物反应性。这些发现为合理使用O2作为Ag生长的调节剂铺平了道路。
The use of gaseous species has been proposed in the literature to counteract the three-dimensional growth tendency of noble metals on dielectric substrates and favor an earlier percolation without compromising electrical properties. This \"surfactant\" effect is rationalized herein in the case of O2 presence during magnetron sputtering deposition of Ag films on SiO2. In situ and real-time techniques (X-ray
photoemission, film resistivity, UV-visible optical spectroscopy) and ex situ characterizations (X-ray diffraction and transmission electron microscopy) were combined to scrutinize the impact of O2 addition in the gas flow (%O2), revealing three regimes of evolution of film resistivity, morphology, structure, and chemical composition. At low oxygen flow conditions (%O2 < 4), the observed drastic decrease of the percolation threshold is assigned to a combination of (i) a change in nanoparticle density, wetting, and crystallographic texture and (ii) a delayed coalescence effect. The driving force is ascribed to the presence of specific adsorbed oxygen moieties, the nature of which starts evolving at intermediate oxygen flow conditions (10 ≤ %O2 < 20). At high oxygen flow (20 ≤ %O2 < 40), the found detrimental impact on film resistivity is assigned to an actual oxidation in the form of a Ag2O-like poorly crystallized compound. For all %O2, a composition gradient is observed across the film thickness, with a more metallic Ag at the substrate interface. A correlation between percolation and the nature of the detected O moieties is observed. In parallel to an oxygen spillover mechanism, this gradient can be explained by the competition between different surface processes occurring before percolation, namely, aggregation, metal oxidation, and substrate reactivity. Such findings pave the way to a rational use of O2 as a modifier for Ag growth.