Negative ion source (NIABNIS) and preparation of transparent carbon films by negative carbon ion beam deposition

Abstract

A high current heavy negative ion source of the neutral and ionized alkaline metal bombardment type (NIABNIS) has been newly developed for negative ion beam applications such as deposition and implantation. This source is a sputter type, and the sputtering target is placed on the extractor of a cesium plasma ion source in order to obtain a large current of cesium ions bombarding the target simultaneously with a controlled amount of neutral cesium atoms. The work function of the sputtering target surface in operation is kept as low as possible so that a high efficiency of the negative ion production is realized. Mass-separated ion beams of 0.74 mA for C −, 200 μA for C 2 −, 320 μA for Cu −, and 170 μA for Si − were obtained. A negative ion beam deposition system with the NIABNIS, in which divergent effects of the ion beam were effectively suppressed, has also been developed. A decelerated C − ion current of several tens of μA in the range of a final energy of 25–100 eV, and about 100 μA in the range higher than 100 eV was obtained. By using C − and C 2 − ion beams with an energy of 10–1000 eV, transparent carbon films of several thousands of Å in thickness were deposited.