Mapping deformation in buried semiconductor structures using the hard X-Ray nanoprobe

May 13, 2011
Cross-sectional TEM image of the edge of the SOI/Si3N4 stressor structure. The Si3N4 liner transfers stress into the SOI material. Strain is an important method for optimizing CMOS performance. Nano-XRD allows for the first time in situ nanoscale mapping of lattice strain and tilt within a buried semiconductor layer at high spatial resolution without sectioning the object.

(PhysOrg.com) -- Scientists from IBM's T. J. Watson Research Center and Columbia University, working with the X-Ray Microscopy Group, have mapped rotation and strain fields across a silicon-on-insulator (SOI) structure that included a liner of stressed Si3N4 using X-ray nanodiffraction (nano-XRD) at the CNM/APS Hard X-Ray Nanoprobe beamline.

Inducing strain in semiconductors is an important method to improve performance of (CMOS) devices. One strategy for inducing strain includes the deposition of liner materials that possess residual stress, ultimately producing strain within the CMOS device. However, this strain is heterogeneous at the nanoscale, leading to a wide distribution of environments along current-carrying paths of the structure. Improved understanding of the distribution of strain in CMOS devices is critical for continued improvement of their efficiency. Although a number of techniques have been applied to characterize strain at the nanoscale, none enable the mapping of subsurface regions or buried layers with the high spatial resolution offered by nano-XRD.

Comparison of the measured SOI lattice tilt (squares) to the boundary element (BEM) calculated, depth-averaged rotation distribution (line) of the SOI layer under the Si3N4 stressor. The inset shows the cross-sectional geometry showing the direction of rotation. Deviations from the model indicate nanoscale regions that are not well predicted by elastic, continuum mechanics – potentially offering unique opportunities for strain engineering at the nanoscale.

The new in situ studies reveal the distribution of lattice tilt as a function of position within the structure and also the maximum magnitude of the lattice tilt. The work is significant because it is one of the first nondestructive studies of subsurface strain with spatial resolution better than 100 nm done without sectioning or otherwise modifying the sample.

Modeling is also performed via a boundary element approach. The modeling and experimental results show that strain transfer into the underlying SOI from the liner primarily induces elastic deformation with secondary nanoscale regions exhibiting a unique noncontinuum, nonelastic response that is the subject of further study.

The Hard X-Ray Nanoprobe beamline is jointly managed by the CNM and the X-Ray Science Division of the at Argonne National Laboratory.

Explore further: Better thermal-imaging lens from waste sulfur

More information: C. E. Murray et al., “Nanoscale silicon-on-insulator deformation induced by stressed liner structures,” J. Appl. Phys. 109, 083543 (2011). DOI:10.1063/1.3579421

Related Stories

World’s Most Precise 'Hard X-Ray' Nanoprobe Activated

May 19, 2005

Marking a major step forward in using X-rays to study some of the smallest phenomena in nature, the world’s first “hard X-ray” nanoprobe beamline was activated on March 15, 2005. The unique nanoprobe ...

Stress Management: X-Rays Reveal Si Thin-Film Defects

Jul 06, 2006

Pile-ups, bad on the freeway, also are a hazard for the makers of high-performance strained-silicon semiconductor devices. A sensitive X-ray diffraction imaging technique developed by researchers at the National Institute ...

Tension in the nanoworld

Jan 23, 2009

(PhysOrg.com) -- A joint team of researchers at CIC nanoGUNE (San Sebastian, Spain) and the Max Planck Institutes of Biochemistry and Plasma Physics (Munich, Germany) report the non-invasive and nanoscale ...

Lighting the Way to Better Nanoscale Films

Aug 30, 2004

Most miniature electronic, optical and micromechanical devices are made from expensive semiconductor or ceramic materials. For some applications like diagnostic lab-on-a-chip devices, thin-film polymers may ...

Recommended for you

Better thermal-imaging lens from waste sulfur

5 hours ago

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...

How to test the twin paradox without using a spaceship

Apr 16, 2014

Forget about anti-ageing creams and hair treatments. If you want to stay young, get a fast spaceship. That is what Einstein's Theory of Relativity predicted a century ago, and it is commonly known as "twin ...

User comments : 0

More news stories

Better thermal-imaging lens from waste sulfur

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...

Robotics goes micro-scale

(Phys.org) —The development of light-driven 'micro-robots' that can autonomously investigate and manipulate the nano-scale environment in a microscope comes a step closer, thanks to new research from the ...

Hackathon team's GoogolPlex gives Siri extra powers

(Phys.org) —Four freshmen at the University of Pennsylvania have taken Apple's personal assistant Siri to behave as a graduate-level executive assistant which, when asked, is capable of adjusting the temperature ...

Deadly human pathogen Cryptococcus fully sequenced

Within each strand of DNA lies the blueprint for building an organism, along with the keys to its evolution and survival. These genetic instructions can give valuable insight into why pathogens like Cryptococcus ne ...