Strain relaxation of epitaxial SiGe layers on Si(100) improved by hydrogen implantation

Mantl, S.; Holländer, B.; Liedtke, R.; Mesters, S.; Herzog, H.‐J.; Kibbel, H.; Hackbarth, T.

doi:10.1016/s0168-583x(98)00601-6

Cited by 66 publications

(37 citation statements)

References 19 publications

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“…3 Recently, it was shown that He + ion implantation and subsequent thermal annealing can successfully be employed to relax the strain of thin pseudomorphic SiGe layer grown on Si͑100͒. [4][5][6] The required He + implantation doses to achieve substantial strain relaxation during the subsequent annealing are in the range of 5 ϫ 10 15 cm −2 to 2 ϫ 10 16 cm −2 . These relatively high doses lead to long implantation times and limit throughput of wafers in production and form voids in the underlying silicon.…”

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confidence: 99%

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Strain relaxation of pseudomorphic Si1−xGex∕Si(100) heterostructures after Si+ ion implantation

Holländer

Buca

Mörschbächer

et al. 2004

Journal of Applied Physics

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The strain relaxation of pseudomorphic Si 1−x Ge x layers ͑x = 0.21, . . . , 0.33͒ was investigated after low-dose Si + ion implantation and annealing. The layers were grown by molecular-beam epitaxy or chemical vapor deposition on Si͑100͒ or silicon-on-insulator. Strain relaxation of up to 75% of the initial strain was observed at temperatures as low as 850°C after implantation of Si ions with doses below 2 ϫ 10 14 cm −2 . We suggest that the Si implantation generates primarily dislocation loops in the SiGe layer and in the underlying Si which convert to strain relaxing misfit segments. Strained Si films grown on strain-relaxed SiGe buffer layers will soon be applied for advanced microelectronic devices since strained Si exhibits significantly enhanced carrier mobilities and therefore, yields to transistors with higher transconductance and drive currents.1,2 However, a key problem is the fabrication of thin strain relaxed SiGe buffer layers, which serve as virtual substrates for the growth of strained silicon. The standard approach is the growth of several micrometer thick, compositionally graded buffer layers. 3Recently, it was shown that He + ion implantation and subsequent thermal annealing can successfully be employed to relax the strain of thin pseudomorphic SiGe layer grown on Si͑100͒.4-6 The required He + implantation doses to achieve substantial strain relaxation during the subsequent annealing are in the range of 5 ϫ 10 15 cm −2 to 2 ϫ 10 16 cm −2 . These relatively high doses lead to long implantation times and limit throughput of wafers in production and form voids in the underlying silicon. Previously it was shown that strain relaxation can also be achieved by H + implantation and annealing.4 However, this method was only successful forSiGe layers with Ge concentrations below 25 at. %. Enhanced strain relaxation due to the introduction of point defects by Ge + ion implantation at 400°C or the implantation of dopants ͑B,As͒ was reported, however, without revealing the resulting microstructure. 7,8 The use of ion implantation for strain relaxation has several advantages: It is easy to use, is highly reproducible, is area-selective by the use of masks, and is fully compatible with existing Si technology. Therefore, there is interest in the development of an ion implantation method, which allows efficient strain relaxation after annealing at moderate temperatures while maintaining a high sample quality. It is important to use ions, which require only a low dose and avoid contamination or unintended doping by the implanted ions.In this work, we have investigated the strain relaxation of pseudomorphic Si 1−x Ge x layers induced by low dose Si + ion implantation at room temperature and subsequent annealing. We also provide a preliminary explanation for the mechanism of strain relaxation. The layers were grown by chemical vapor deposition (CVD) and solid-source molecular-beam-epitaxy (MBE) on Si͑100͒ and on siliconon-insulator (SOI) wafers. The samples were characterized using transmission electron microsco...

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“…Previously it was shown that strain relaxation can also be achieved by H + implantation and annealing. 4 However, this method was only successful for…”

mentioning

confidence: 99%

Strain relaxation of pseudomorphic Si1−xGex∕Si(100) heterostructures after Si+ ion implantation

Holländer

Buca

Mörschbächer

et al. 2004

Journal of Applied Physics

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“…Many methods devised over the years have been more or less successful in reducing the density of TDs, such as strained-layer superlattice formation 6 , compositional grading 7,8 , intentional introduction of point defects followed by thermal annealing [9][10][11] , and limited-area growth. The latter has been accomplished either by substrate patterning [12][13][14] or by selective area deposition (SAD) into dielectric windows present on a flat substrate [15][16][17][18][19][20] .…”

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X-Ray Nano-Diffraction on Epitaxial Crystals

Meduňa¹,

Falub²,

Isa³

et al. 2014

Quant. Matt

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The concept of growing epitaxial Ge and SiGe crystals onto tall Si pillars may provide a means for solving the problems associated with lattice parameter and thermal expansion coefficient mismatch, i.e., dislocations, wafer bowing and cracks. For carefully tuned epitaxial growth conditions the lateral expansion of crystals stops once nearest neighbors get sufficiently close. We have carried out scanning nano-diffraction experiments at the ID01 beam-line of the European Synchrotron Radiation Facility (ESRF) in Grenoble on the resulting space-filling arrays of micron-sized crystals to assess their structural properties and crystal quality. Elastic relaxation of the thermal strain causes lattice bending close to the Si interface, while the dislocation network is responsible for minute tilts of the crystals as a whole. To exclude any interference from nearest neighbors, individual Ge crystals were isolated first by chemical etching followed by micro-manipulation inside a scanning electron microscope. This permitted us to scan an X-ray beam, focused to a spot a few hundreds of nm in size, along the height of a single crystal and to record three-dimensional reciprocal space maps at chosen heights. The resolution limited width of the scattered X-ray beams reveals that the epitaxial structures evolve into perfect single crystals sufficiently far away from the heavily dislocated interface.

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“…However, they do not mention the low-temperature Si ͑LT-Si͒ technique, 5,6 the LT-SiGe technique, 7 or the He/ H implantation technique. 8,9 All of these methods have given much better quality material than that presented in Ref. 1, with rms roughness of around 1 nm in most cases.…”

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Comment on “Smooth relaxed Si0.75Ge0.25 layers on Si(001) via in situ rapid thermal annealing” [Appl. Phys. Lett. 83, 4321 (2003)]

Chrastina

2004

Applied Physics Letters

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Strain relaxation of epitaxial SiGe layers on Si(100) improved by hydrogen implantation

Cited by 66 publications

References 19 publications

Strain relaxation of pseudomorphic Si1−xGex∕Si(100) heterostructures after Si+ ion implantation

Strain relaxation of pseudomorphic Si1−xGex∕Si(100) heterostructures after Si+ ion implantation

X-Ray Nano-Diffraction on Epitaxial Crystals

Comment on “Smooth relaxed Si0.75Ge0.25 layers on Si(001) via in situ rapid thermal annealing” [Appl. Phys. Lett. 83, 4321 (2003)]

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