APPLICATION OF X-RAY SCANNING COMBINED WITH ACOUSTIC WAVES EXCITATIONS TO THE STRAIN STUDIES IN SILICON WAFERS. E.Raitman, E.Iolin, B.Kuvaldin, V.Gavrilov, L.Rusevich, Institute of Physical Energetic, Riga, LV-1006, Latvia

High resolution many crystals X-ray diffractometry is now widely accepted for small strains studying in perfect crystals. However it is partly impractical for the industry because these techniques are complicated and need a lot of time for measurements. Recently [1,2] it was shown that the effects of high frequency acoustic waves (AW) on the X-ray diffraction are qualitatively different for perfect and slightly deformed silicon single crystals. These results were applied to the studies of the strain distribution in industrial silicon single crystal wafers. It has been shown that the quantity R=(Is-Io)/Io is proportional to the value of the static deformation gradient in the many- phonons AW excitation regime (Is, Io are the intensities of the diffracted X-ray beams, when an AW are excited and without AW, respectively). The specific results of such technique application are obtained, namely: a) distribution of strains in the "perfect" plates over the diameter D=120 mm; b) the same on the some wafers after their different finishing treatments; c) distributions of strain around the microwires soldered to the wafer; d) strain distributions inside and outside the windows made in the SiO2 coating, (a scanning step 0.1mm). The fine structure of strains over the scanning path was observed. It is shown (in general) that the X-ray scanning technique combined with simultaneous AW excitations has sensitivity at least not worse than the traditional ones.

1. E.M.Iolin, E.A.Raitman, et al., Zh. Eksp. Teor. Fiz. 94, 218 (1988).

2. E.M.Iolin, E.A.Raitman, V.N.Gavrilov, B.V.Kuvaldin and L.L.Rusevich., J. Phys. D.: Appl. Phys. 28, A218 (1995).