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

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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