Nanoscale patterning induced strain redistribution in ultrathin strained Si layers on oxide.
We present a comparative study of the influence of the thickness on the strain behavior upon nanoscale patterning of ultrathin strained Si layers directly on oxide. The strained layers were grown on a SiGe virtual substrate and transferred onto a SiO(2)/Si substrate using wafer bonding and hydrogen ion induced exfoliation. The post-patterning strain was evaluated using UV micro-Raman spectroscopy for thin (20 nm) and thick (60 nm) nanostructures with lateral dimensions in the range of 80-400 nm. We found that about 40-50% of the initial strain is maintained in the 20 nm thick nanostructures, whereas this fraction drops significantly to approximately 2-20% for the 60 nm thick ones. This phenomenon of free surface induced relaxation is described using detailed three-dimensional finite element simulations. The simulated strain 3D maps confirm the limited relaxation in thin nanostructures. This result has direct implications for the fabrication and manipulation of strained Si nanodevices.
Moutanabbir
O
O
Max Planck Institute of Microstructure Physics, Halle (Saale), Germany. moutanab@mpi-halle.mpg.de
Reiche
M
M
Hähnel
A
A
Erfurth
W
W
Gösele
U
U
Motohashi
M
M
Tarun
A
A
Hayazawa
N
N
Kawata
S
S