Time-Dependent Relaxation of Strained Silicon-on-Insulator Lines Using a Partially Coherent X-Ray Nanobeam

Abstract

We report on the quantitative determination of the strain map in a strained Silicon-On-Insulator (sSOI) line with a 200 × 70 nm 2 cross-section. In order to study a single line as a function of time, we used an X-ray nanobeam with relaxed coherence properties as a compromise between beam size, coherence and intensity. We demonstrate how it is possible to reconstruct the line deformation at the nanoscale, and follow its evolution as the line relaxes under the influence of the X-ray nanobeam.PACS numbers: 41.50.+h, 68.60.Bs New applications in optoelectronic and electronic semiconductor devices have been achieved by a careful control of strain at the nanoscale level. Several physical properties such as charge carrier mobility in transistors and emission wavelength in quantum dots or well heterostructure have been advantageously improved by applying strain fields adapted to the materials band structure, orientation and doping features [1][2][3][4].The measurement of these strain fields has required the development of dedicated techniques with adapted spatial and strain resolution. Electronic imaging techniques have seen tremendous developments and outstanding achievements [5], but are always limited by the preparation of thin foil that can considerably relieve internal stress in nanostructures. Very recently, X-ray diffraction has taken profit of the highly brilliant and coherent radiation provided by synchrotron sources [6]. Moreover, the optimization of dedicated focusing optics (compound refractive lenses [7], Fresnel Zone Plate (FZP) [8,9], Kirkpatrick-Baez mirrors [10,11]) has allowed the use of nanobeams, increasing the spatial resolution of diffraction measurements. This also allowed the use of coherent X-ray diffraction imaging (CXDI) for structure (shape, size) and strain determination of single nano-objects [12][13][14][15][16].In this letter, we illustrate how the strain of a single strained silicon nanostructure changes during irradiation with x-rays, as a function of measurement time using a partially coherent X-ray nanobeam. Strained SiliconOn-Insulator (sSOI) lines are considered due to their strong interest for enhancing the carrier mobility in metal oxide semiconductors field-effect-transistors (MOSFET) devices [17,18].Silicon lines were etched from a (001) oriented sSOI substrate made by a wafer bonding technique from the Si deposition on a SiGe virtual substrate imposing a biaxial strain, as described in [19]. Lines in tensile strain ( yy = +0.78%) are oriented along the [110] direction which corresponds to the usual direction of n-MOSFET channels for which electron transport is improved. The strain relaxes elastically along [110], i.e. perpendicularly to the lines [18]. An in-plane misorientation of about 1 o is used between the strained Si lines and the Si substrate in order to separate the line and substrate Bragg peaks. The sSOI lines have a width W=225 nm and a height H=70 nm (Fig. 1) and lie on a 145 nm SiO 2 layer. The distance d between two adjacent lines is about 775 nm. Grazing-incid...

X-ray diffraction strain analysis of a single axial InAs1–xPxnanowire segment

“…the diagonal intensity stripes in the measurement are not reflected in the simulation. A more precise approach for the estimation of the focused beam's properties was used by Mastropietro et al (2013), where the beam size and shape was calculated from the estimated undulator source size and the utilized FZP, and Schropp et al (2010) have analyzed the beam properties using ptychography experiments, resulting in a detailed picture of the focused beam's shape and coherence properties. Taking into account those beam profiles does not, however, improve our simulation results any more.…”

Beam damage of single semiconductor nanowires during X-ray nanobeam diffraction experiments

“…The structural damage induced by the absorbed X-ray dose was shown to occur only when an oxide layer is present under the Si thin film. Whereas Polvino et al (2008) reported that the exposure induced permanent structural damage to the crystal structure, Mastropietro et al (2013) have shown that the intense radiation only damages the Si /Si-on-insulator interface but not the crystalline Si structure. Aside from SiC and GaN which potentially offer radiation-hard alternatives to silicon devices (Sellin & Vaitkus, 2006), bulk or layered GaAs is known to be a very radiation-hard material suitable for X-ray detectors (Claeys & Simoen, 2002;Lioliou & Barnett, 2016;Smolyanskiy et al, 2018).…”

“…the authors have observed a splitting of the Bragg reflections, which continuously evolves with increasing X-ray dose. Working on similar systems, Mastropietro et al (2013) quantitatively demonstrated elastic strain relaxation in single Si-on-insulator lines under the influence of prolonged X-ray exposure. This was done by monitoring the evolution of the 11 " 3 3 Bragg peak while illuminating the same position for different time intervals.…”

Toward one nanometer X-ray focusing: a complex refractive lens design

“…X-ray nanoprobe can provide local information at nanoscale, which will benefit investigation on the nanoscale inhomogeneous samples. Nowadays, X-ray nanoprobe plays an important role in many research fields, ranging from materials science, to geophysics and environmental science, to biophysics and protein crystallography [1][2][3][4][5] . Toward focusing X-ray beam to nanoscale efficiently, great efforts have been paid.…”