Scanning x-ray microscopy imaging of strain relaxation and fluctuations in thin patterned SiGe-on-insulator nanostructures

Abstract

Strain engineered performance enhancement in SiGe channels for p-MOSFETs is one of the main drivers for the development of microelectronic technologies. Thus, there is a need for precise and accurate strain mapping techniques with small beams. Scanning X-Ray Diffraction Microscopy (SXDM) is a versatile tool that allows measuring quantitative strain maps on islands as thin as 13 nm quickly. From the high velocity and robustness of the technique, statistical information can be extracted for a large number of individual islands of different sizes. In this paper, we used the advantages of SXDM to demonstrate the effectiveness of the condensation method used to grow ultra-thin layers of strained SiGe and to determine their relaxation lengths at patterned interfaces.

Lattice Strain and Defects Analysis in Nanostructured Semiconductor Materials and Devices by High‐Resolution X‐Ray Diffraction: Theoretical and Practical Aspects

“…Hence the use of a small X-ray beam, comparable (or smaller) to the size of the heterogeneities is crucial. [44] This relates to the development of new highresolution diffraction techniques like scanning X-ray diffraction microscopy, [38,45,46] which have emerged in very recent years. Considering also the development of diffracting devices such as Fresnel zone plates, gratings, pine-holes, etc., coherent diffraction imaging, [47,48] Bragg coherent diffraction imaging, [49][50][51] and others are in the center of extensive research.…”

Strain distributions in carbon-doped silicon nanowires along [110] and [100] investigated by X-ray diffraction

“…Such strain relaxations around the edge of nanofabricated structures have also been reported for SiGe and SiGe-on-insulator. 14,16,17,22,23) Residual strains in relaxed regions decrease from the bottom to the top layers. The most relaxed positions are both edges on the top layers of all nanowires.…”

“…Local strains in nanostructures have been extensively studied by Raman spectroscopy, 2,4,8,13,16,17,20,21) microbeam X-ray diffraction, 3,7,9,10,12,14,15,19,23) electron backscattering pattern 16,17) and dark field electron holography. 5,6,18,22) These methods give excellent results with very fine spatial resolution but are not suitable for statistical investigations since local and individual characteristics are emphasized By observing samples with many nanowires periodically arranged within a 1.5 mm × 1.5 mm region with X-rays of sub-millimeter beam width, we obtained statistically averaged characteristics while eliminating the effects of individual nanowire differences, as previously reported.…”