(1. 中南大学 冶金与环境学院，湖南 长沙，410083；
2. 中国恩菲工程技术有限公司，北京，100038；
3. 多晶硅材料制备技术国家工程实验室，河南 洛阳，471023；
4. 难冶有色金属资源高效利用国家工程实验室，湖南 长沙，410083)
摘 要: 六氯乙硅烷作为高品质氮化硅和氧化硅薄膜的硅源前驱体，主要用于DRAM和NAND Flash存储器的制造以及特征尺寸28 nm以下逻辑芯片的制备，在半导体制造中已被广泛应用。目前国内采用六氯乙硅烷生产技术已制备集成电路，但其十亿分之一量级的超痕量金属杂质检测是国内的检测技术瓶颈，也是国外技术封锁的项目之一。为此，研究六氯乙硅烷的水解过程产生的微颗粒吸附固化金属杂质的机理，采用氢氟酸消解产生的SiF4的强挥发性，以消除硅基效应导致的基体干扰。在此基础上，建立六氯乙硅烷中Li，Na，Mg，Al，K，Ca，Ti，V，Cr，Mn，Fe，Co，Ni，Cu，Zn，Ga，As和Pb共18种金属杂质的电感耦合等离子体质谱(ICP-MS)检测方法，并确定质谱激发模式和最优仪器参数。研究结果表明：采用这种消解方法可以获得较好的检测效果：标准曲线线性相关系数大于0.999，各元素检出限低于0.10 ng/g，加标回收率为80%~110%，方法精密度小于10%。对比酸雾消解法和直接消解法对硅基体的消解效果，发现酸雾消解法作为样品前处理方式更加安全、洁净、准确和高效。精密度和准确度符合超痕量杂质检测方法的规定，再现性满足用户要求，适用于六氯乙硅烷中金属杂质的检测，其他高纯度氯硅烷的杂质测试亦可参照使用。
关键字: 六氯乙硅烷；ICP-MS；金属杂质；酸雾消解
（1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. China ENFI Engineering Co. Ltd., Beijing 100038, China;
3. National Engineering Laboratory of Polysilicon Materials Manufacturing Technology, Luoyang 471023, China;
4. National Engineering Laboratory of Efficient Utilization of Refractory Nonferrous Metal Resources, Central South University, Changsha 410083, China）
Abstract:Hexachlorodisilane was widely used as an appropriate precursor of fabricating high quality silicon nitride and silicon oxide thin films for DRAM, NAND Flash memory and logic chips at 28 nm technology node and below. At present, the breakthrough of hexachlorodisilane production for integrated circuit has been achieved in China. However, the detection method of trace metal impurities with parts per billion(ppb) level was still one of the key technical blockade projects. In this work, the adsorption and solidification mechanism of metal impurities with the particles formed in the hydrolysis of hexachlorodisilane were studied. The strong volatilization of SiF4 produced by hydrofluoric acid digestion eliminates the matrix interference caused by silicon-based effect. 18 metal impurities in hexachlorodisilane such as Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As and Pb were detected by the inductively coupled plasma mass spectrometry(ICP-MS) based on the present method. The mass spectrometry excitation mode and optimal instrument parameters were also determined. The acid mist digestion technique was proved to be a safer, cleaner, more accurate and efficient pre-treatment method compared with direct digestion method. The optimal detection results show that the linear correlation coefficient of the standard curve is larger than 0.999 and the detection limit of each element is lower than 0.10 ng/g. The recovery rate of the standard addition ranges from 80% to 110%, and the relative standard deviation is less than 10%. The precision and accuracy of the method can meet the detection and reproducibility requirements of trace metal impurities. Accordingly, it should be suitable for the detection of metal impurities for hexachlorodisilane and other high purity chlorosilanes.
Key words: hexachlorodisilane; ICP-MS; metal impurities; acid mist digestion
