Hydrogen plasma etching method for depth analysis by x‐ray photoelectron spectroscopy

An etching device using a hydrogen plasma has been developed for x-ray photoelectron spectroscopy (XPS) depth profile analysis of organic compounds. The effect of the hydrogen plasma discharge was investigated using a photoresist film containing benzene rings, C– O bonds and C– F bonds formed on an Si(100) wafer. The condenser-type discharge tube employed is composed of electrodes, an etch tunnel (shield tube) and a quartz glass tube. Both the electrodes and etch tunnel have many holes. Experimental results show that the etching rate of the photoresist film is 26.7 nm min−1 at an r.f. power of 200 W, a gas flow rate of 6.0 cc min−1 and a hydrogen gas pressure of 26.6 Pa. This rate is higher than that achieved by the use of a conventional high-speed etching ion gun. It is observed that the etched surface is flatter than that obtained by parallel plate electrodes and an Ar ion beam. The amounts of C, O and F after hydrogen plasma etching were not remarkably different from those before etching, and the shape of the C 1s spectrum did not show any change, indicating no change in chemical bonding. The results show that hydrogen plasma etching is very effective for depth profile analysis of organic polymers by XPS. Copyright © 2000 John Wiley & Sons, Ltd.

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