Development of Charge-up Free lon lmplantation by Using Negative lon Beam

本研究取得了以下成果：(1)负离子注入使注入表面的充电电压显著降低；(2)负离子注入作为一种自由充电离子注入技术在大规模集成电路制造工艺中有较大的应用前景。本文研究的五个主要课题及取得的成果如下：用于负离子注入的大电流负离子源的发展等离子溅射型重负离子源已经开发出来，它能够提供半导体制造过程中负离子注入所需的硼、磷和硅元素的几毫安的负离子电流。负离子注入过程中绝缘子充电电位测量系统的研制利用二次电子-多能级分析方法，建立了负离子注入过程中绝缘子充电电位测量方法。负离子注入绝缘体的充电电位只有几伏特的负极性。负离子注入过程中充电机理的分析研究揭示了负离子注入过程中孤立电极的充电机理，其中充电电压由二次电子发射产率和电子能量分布两个因素决定。对于绝缘子，目前还不清楚绝缘子的充电机理，但我们提出了一个在绝缘子近表面形成双层电层的模型。大面积注入负离子束输运系统的研制针对负离子注入器，研制了直径为6英寸的大型硅衬底的负离子束输运系统。测试栅极氧化层的测试器件（TEG: test element group）采用负离子注入，几乎所有器件在负离子注入后都具有良好的性能，无需任何外部器件进行充电补偿。少

This research has been accomplished with following results : (1) It was found that negative-ion implantation makes it remarkably low the charge-up voltage of the implanted surface, and (2) the large possibillity was obtained to put the negative-ion implantation to practical use in the LSI fabrication process and as a charge-up free ion implantation technique. Five main subjects of the research and obtained results are described as follows.1.Development of High Current Negative Ion Source for Negative-Ion ImplantationRF plamsa-sputter-type heavy negative-ion source has been developed which was able to deliver several mA negative-ion current of boron, phosphorus and silicon elements desired in negative-ion implantation for the semiconductor fabrication process.2.Development of the Mesuring System of Charg-up Potential of Insulators during Negative-Ion ImplantationThe method for measuring charge-up potential of insulators during implantation has been developed by using secondary-electron- … More energy analysis. Charge-up potential of negative-ion implantated insulators was revealed to be within only several volts of negative-polarity.3.Analytical Research of Charging Mechanism in Negative-Ion ImplantationThe charging mechanism of isolated electrode during negative-ion implantation has been revealed, where the charging voltage was determined by two factors of secondary-electron-emission yield and electron-energy distribution. As for the insulators, the charging mechanism of insulators is not made clear yet, but we have presented a model of electric-double-layr formed in near surface of insulator.4.Development of Negative-Ion Beam Transport System for a Large Area ImplantationFor negative-ion implanter, the beam transport system has been developed for a large silicon substrate of 6 inch in diameter.5.Evaluation of Negative-Ion Implanted DeviceThe test devices (TEG : test element group) for testing gate oxide layr were implanted with negative-ion beam, and as a result, almost all devices performed well after the negative-ion implantation without any external apparatus for charge-up compensation. Less