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金属钽可作为集成电路中铜与硅基板的阻隔层材料,以防止铜与硅扩散生成铜硅合金影响电路性能。采用钽靶材通过物理气相沉积技术溅射钽到硅片上。靶材晶粒尺寸与织构取向影响溅射速率及溅射薄膜均匀性,要求钽靶材晶粒尺寸应小于100μm,在靶材整个厚度范围内应主要是(111)型织构。同时,为了避免薄膜存在杂质颗粒,要求钽靶材纯度不小于99.99%。本文对钽靶材电子束熔炼、锻造、轧制、热处理等关键工艺进行了系统研究,找到了一种有别于常规钽靶材生产工艺的新方法,所生产产品化学纯度、晶粒尺寸、织构等性能优良,产品成品率高,适于批量化生产。
Metal tantalum can be used as a barrier layer of copper and silicon substrates in integrated circuits to prevent copper and silicon from diffusing to form copper-silicon alloys that affect circuit performance. Tantalum is sputtered onto the silicon wafer by physical vapor deposition using a tantalum target. The grain size and texture orientation of the target affect the sputtering rate and the uniformity of the sputtered film. The grain size of the tantalum target is required to be less than 100 μm and the (111) texture should be predominant over the entire thickness of the target. At the same time, in order to avoid the presence of impurity particles in the film, tantalum target purity of not less than 99.99% is required. In this paper, the key technologies such as electron beam melting, forging, rolling and heat treatment of tantalum target were systematically studied, and a new method different from the conventional production process of tantalum target was found. The chemical purity, grain size, Texture and other excellent performance, high product yield, suitable for mass production.