Measuring Strain Field of Semiconductor Surface Structure by Dynamical Effects of X-ray Bragg-surface Diffraction
| Autor: | Chu, Chia-Hung, 朱家宏 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 X-ray three-beam Bragg-surface diffraction (BSD) is a technique to measure the strain field near surface or buried interface of a substrate in a thin film system, using a surface reflection of X- ray multiple diffractions. The surface diffracted beam propagates along the surface/interface and provides the information about surface/interface structure. According to the dynamical theory of X-ray diffraction, the penetration depth of a surface reflection in the 3-beam geometry is a function of the deviation of azimuthal angle ( ) from the exact position for the 3-beam case. Also from the numerical calculations the depth can be determined, for example, for a Si substrate the penetration depth is from 10 to 373A, and for GaAs is 15 to 250A. Combining with the lattice parameters measured from CCD images of the surface diffracted beam, we can obtain the distribution of 3-D strain field versus depth. The experiments were carried out at National Synchrotron Radiation Research Center (NSRRC). Two sample systems were tested: Si-Fe interface effected in a multi-components film (β-FeSi2, FeSi) and chemical etched surface of GaAs and InAs. Using the BSD method the strain field of a Si substrate due the 3 structures, β-FeSi2, FeSi and decorated grain boundary, were measured simultaneously. Within the range of 15-70A in depth, the largest variations of lattice parameters are +0.004% for β-FeSi2 and -0.004% for FeSi. The results for GaAs and InAs are not as detail as the former. The largest strain detected of GaAs is -0.0015% at 77A below the surface. For the InAs surface the surface roughness effect detected is shown in the images by changing or distorting the pattern of surface diffracted beam. The relaxation of broken structure along certain specific directions is observed for both GaAs and InAs. In brief, the X-ray Bragg-surface diffraction has the capabilities of extracting initial information of lattice distortion qualitatively and realizing precise measurements quantitatively. Moreover it is an non-destructive measuring technique. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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