FIZIKA A 4 (1995) 2, 245-253

size 210 kB

THERMAL STABILITY OF W1-xSix/Si MULTILAYERS FOR X-RAY OPTICS

EVA MAJKOVA*, MATEJ JERGEL*, RUDOLF SENDERAK*, STEFAN LUBY**
and MIROSLAV BABINSKY***
*Institute of Physics, Slovak Acad. Sci., 842 28 Bratislava, Slovak Republic
**Department of Electrotechnology, Slovak Techn. Univ., 812 19 Bratislava, Slovak Republic
***Dept. of Microelectronics, FEI, Slovak Technical University in Bratislava, Bratislava, Slovak Republic

Received 7 April 1995

The thermal stability of multilayers (MLs) for X-ray mirrors can be increased by using a pair of materials in thermodynamic equilibrium. This was achieved by doping the W-layer by Si to decrease the driving force of interdiffusion. The W0.66Si0.33/Si, W0.5Si0.5/Si, W0.33Si0.66/Si and, for comparison, W/Si MLs with ten bilayers were fabricated by electron-beam deposition in UHV onto oxidized Si substrates. The nominal thickness was 5.5 nm for Si and 2.5 nm for W or W1-xSix layers. The samples were heat treated by halogen-lamp rapid thermal annealing and by standard annealing in vacuum up to 1000 C for 30 s and 25 min, respectively. Samples were analyzed by X-ray reflectivity and large angle X-ray diffraction measurements. From the results follows an increased stability of W1-xSix/Si MLs in comparison with the W/Si ones. The temperature which the sample can withstand without a serious damage increased from 500 to 850 C with x increasing from 0 to 0.66 . As-deposited, MLs were amorphous. The crystalline bcc W or WSi2 phases appeared at 500 C for x 0.5. For x = 0.66, a well developed WSi2 was obtained only after annealing at 1000 C. Hence, Si helps to keep W in the amorphous state.

UDC 538.953
PACS 68.65.+q
Copyright by The Croatian Physical Society
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