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采用XPS方法,通过对刻蚀前后BST(钛酸锶钡)薄膜表面成分、元素化合态以及原子相对百分含量分析,探讨了CHF3/Ar等离子刻蚀BST薄膜的RIE(反应离子刻蚀)机理.研究结果表明,在刻蚀过程中,金属Ba,Sr,Ti和F等离子体发生化学反应并生成相应的氟化物且部分残余在薄膜表面,因为TiF4具有高挥发特性,残余物几乎没有钛氟化物.然而,XPS表明Ti-F仍然少量存在,认为是存在于Metal-O-F这种结构中,而O1s进一步证实了Metal-O-F的存在.基于原子的相对百分含量,我们发现刻蚀后薄膜表面富集氟,源于高沸点的氟化物BaF2和SrF2沉积,导致刻蚀速度仅达12.86nm/min.同时并没有发现C-F多聚物的形成,因此去除残余物BaF2和SrF2有利于进一步刻蚀.针对这种分析结果,本文提出对BST薄膜每4min刻蚀后进行1minAr等离子体物理轰击方案,发现残余物得以去除.
By XPS method, the RIE (reactive ion etching) mechanism of CHF3 / Ar plasma etching BST thin film was discussed through the analysis of the surface composition, elemental chemical composition and relative atomic percentage of BST films before and after etching The results show that during the etching process, the metal Ba, Sr, Ti and F plasmas react chemically to form the corresponding fluoride and partially remain on the surface of the film because TiF4 has high volatility and almost no titanium fluoride However, XPS indicates that Ti-F is still present in small amounts, believed to exist in the Metal-OF structure, and O1s further confirms the presence of Metal-OF. Based on the relative atomic percentages, we found that the etched film The surface is enriched with fluorine, resulting from the deposition of high-boiling-point fluoride compounds, BaF2 and SrF2, resulting in an etch rate of only 12.86 nm / min. At the same time, no formation of CF polymer was observed, so removal of the residues BaF2 and SrF2 facilitated further etching In response to this analysis, this paper proposed a 1-minute Ar plasma bombardment of BST film every 4 minutes and found that the residue was removed.