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本文报导根据美国军用标准MIL-STD-883D第1005条规定对半导体器件进行加载寿命实验后金属丝键合点的失效情况。失效的金属丝键合点是在0.8～1.0密耳粗的金丝与半导体表面的铝层之间进行热超声键合形成的。在作加载寿命实验之前,全部金丝键合点都经过了MIL-STD-883D第2023条规定的非破坏性拉力实验。发现失效的金丝键合点在界面有腐蚀性产物。在这些腐蚀性产物内,用俄歇电子能谱仪分析测定出硫、氯、碳、氟和钠等元素。发现氟是铝层内的主要沾污,而且如果氟不存在腐蚀性,似乎就不会产生沾污。电子能谱化学分析确定,在腐蚀性产物中含有(CHFCH_2)n、C_4F和K_3AlF_6。可以肯定,在半导体芯片制造过程中,由于不恰当的等离子工艺,氟原子可能渗入到了铝层内部。诸如电路电压、管壳内的温度以及存在的其它沾污源等因素,很可能加速被氟化物沾污了的铝金属化层的总腐蚀趋势。本文还评价了还没有成功的清除氟沾污的各种技术,如氧等离子处理、紫外线/臭氧处理和去离子水冲洗等。
This article reports the failure of the wire bond point after a semiconductor device has been subjected to a loading life test in accordance with section 1005 of the US military standard MIL-STD-883D. The failed wire bonds are formed by thermosonic bonding between 0.8-1.0 mil thick gold wires and the aluminum layer on the semiconductor surface. Prior to the loading life test, all gold wire junctions were subjected to the non-destructive pull test specified in MIL-STD-883D Section 2023. It is found that the failed gold bonding point has a corrosive product at the interface. Within these corrosive products, elements such as sulfur, chlorine, carbon, fluorine and sodium are determined by Auger electron spectroscopy. Fluorine was found to be the major contamination in the aluminum layer, and it appears that no fouling occurs if fluorine is not corrosive. Electron spectroscopy chemical analysis confirmed that the corrosive products contained (CHFCH 2) n, C_4F and K_3AlF_6. To be sure, fluorine atoms may penetrate inside the aluminum layer due to improper plasma processes during semiconductor chip manufacturing. Factors such as circuit voltage, temperature inside the package, and other sources of contamination present are likely to accelerate the overall corrosion tendency of fluoride-contaminated aluminum metallization. The paper also evaluated various technologies that have not been successfully used to remove fluorine contamination, such as oxygen plasma treatment, UV / ozone treatment and deionized water rinsing.