Some Characteristics of X-Ray Multilayered Thin Films Made with A Plasma Controlled System

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ABSTRACT Multilayered structures with small periods were fabricated using RF-magnetron sputtering device. The conditions of deposition and small changes in the plasma during all deposition period was investigated by optical emission spectroscopy. We studied influence of different parameters (pressure, power, sputtered material) to emission lines corresponding to the working gas Ar and W or Si. Structure and properties of multilayers were estimated, using transmission electron microscopy (TEM) and small-angle x-ray (1.54 A) scattering techniques. The results was compared with emission line intensities of Ar, W and Si and self-bias data written for each layer with computer during multilayer fabrication. We discuss X-ray reflection properties of multilayers fabricated under our conditions and correlation of emission spectroscopy analysis data with another parameters of plasma (self-bias). INTRODUCTION The usefulness of optical emission spectroscopy (OES) for diagnostics and process control during glow discharge etching and deposition has been already shown clearly by several authors [1,2]. OES measurement have been reported by T. Mehdi and al.[3] with rf planar magnetron discharge in argon with discharge gas pressure between 7 and 150 mTorr. In the present work OES have been undertaken with rf magnetron sputtering system with discharge gas pressure between 0,5 and 10 mtorr. We have observed new behaviour of lines which are very different from DC magnetron discharge. We have chosen the OES technique in order to obtain a better insight into the discharge phenomena occurring in the glow discharge near the target during rf magnetron sputtering for multilayer fabrication. Successful use of RF magnetron sputtering for fabrication of multilayers requires good control of deposition conditions. In this paper, we report some results of investigation of rf plasma by optical spectroscopy technique and first observations of a b uncontrolled changes in deposition conditions of multilayer structures

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EXPERIMENTAL PROCEDURE Multilayers were prepared by rf magnetron sputtering. Fig. 1 shows schematically the equipment. The production system is described

1,2 Cathodes

3 Plasma

4 Sample

5 Rotatling Substrate holder 6 Rotating Shutter

Fig 1 Schematic diagramof the magnetron system a) general view, b) principle 95

Mat. Res. Soc. Symp. Proc. Vol. 382 0 1995 Materials Research Society

elsewhere [4] giving detailed characteristics of the

operating principle.

Pumpi system

The light emitted by the two plasmas has been - - --detected by an optical system shown in Fig.2. The light was guided inside the sputtering chamber by tubes (of 1Substrate C~th cm diameter) with two aluminium mirrors. This system

Ft Shatter V Ps

ýutt-d

Substrate

allows to avoid film deposition on the quartz window

r•°em

separating vacuum part of the system from atmosphere. Outside the chamber the light was guided by an optical fibre (of 0,5 mm core diameter). Emission spectra were recorded with a computercontrolled CP200 spectrograph of Jobin-Yvon equip