Si + ion implantation for strain relaxation of pseudomorphic Si1−xGex/Si(100) heterostructures

Holländer

et al. 2011

J. Electrochem. Soc.

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We present a systematic study on the formation of p-type doped strained Si / strained SiGe heterostructures by B + , BF + 2 and (Si + +B + ) ion implantation and annealing at moderate temperatures. The aim of this paper is to address the challenge of conserving the elastic strain during dopant activation. The most important result is that efficient doping combined with the conservation of strain and a good crystalline quality can only be obtained for BF 2 + implants with 1×10 15 ions/cm 2 and anneals at 650 • C. With these parameters, single crystalline layers with negligible strain relaxation and a sheet resistance of 886 /sq were achieved. The implantation of B + requires higher doses to reach low sheet resistances resulting in low layer quality and higher strain relaxation. Si + pre-implantation yields the lowest sheet resistances, but on the expense of strain (relaxation values over 60%). Finally, the optimized ion implantation / anneal parameters were applied for strained SiGe quantum-well MOSFETs with GdScO 3 high-κ gate dielectric.

Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

p-Type Ion Implantation in Tensile Si/Compressive Si_0.5Ge_0.5/Tensile Strained Si Heterostructures

Holländer

et al. 2011

J. Electrochem. Soc.

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“…Most of this defect research was related to transient enhanced diffusion of dopants 20 but also to strain relaxation of thin layers. 21 In SOI, layer recrystallization occurs only if a crystalline seed layer remains after implantation. Recently, it was shown that full strain recovery can be obtained by solid phase epitaxial regrowth ͑SPER͒ of partially amorphized SSOI.…”

Section: A As + Implantation Of Ssoi Layersmentioning

confidence: 99%

“…The thickness of the amorphized Si layer is taken at the critical vacancy concentration value of 18% of the Si atomic density, corresponding to 8.95ϫ 10 21 cm −3 . 21 Figure 4͑b͒ displays the Raman spectra of the unimplanted and as-implanted SSOI layers for different As + ion implanted doses. The peak at 520 cm −1 corresponds to bulk cubic Si, while the second peak, located at 514.5 cm −1 , represents the 0.8% tensile strained Si layer.…”

Section: A As + Implantation Of Ssoi Layersmentioning

confidence: 99%

Elastic strain and dopant activation in ion implanted strained Si nanowires

Habicht

Journal of Applied Physics

et al. 2010

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Strained Si nanowires ͑NWs͒ are attractive for deeply-scaled complementary metal-oxidesemiconductor devices due to the combination of enhanced carrier mobility and excellent electrostatic control as was demonstrated with trigate metal-oxide-semiconductor field effect transistors. The challenge in using strained Si NWs for devices is to preserve the elastic strain during the required processing steps. In this work we investigated the influence of fundamental processing steps like patterning and dopant ion implantation on the structural and transport properties of strained Si layers and NWs on silicon-on-insulator ͑SOI͒ substrates. NWs with widths down to 35 nm, fabricated on 25 nm strained SOI and implanted to doses ranging from 5 ϫ 10 14 to 2 ϫ 10 15 ions/ cm 2 were investigated. We show that strain conservation and a low sheet resistivity of 6.2ϫ 10 −4 ⍀ cm, close to the layer resistivity, can only be obtained if the NWs are patterned on doped layers. For NWs directly implanted to doses above 1 ϫ 10 15 ions/ cm 2 , complete strain relaxation and structural disorder by solid phase recrystallization were observed. In both cases, NWs with widths smaller than 55 nm exhibit an increased specific resistivity.

“…In contrast to the (100) surface orientation, two of the {111} planes are ion implantation and annealing reported in the literature. 5,12,23,31 Yet, the absence of the relaxation for thin and low Ge content SiGe layers on (100) in contrast to the (011) system is not explained.…”

Section: Anisotropy Of Critical Condition For Layer Relaxationmentioning

confidence: 99%

Anisotropy of strain relaxation in (100) and (110) Si/SiGe heterostructures

Trinkaus

Journal of Applied Physics

et al. 2012

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Plastic strain relaxation of SiGe layers of different crystal orientations is analytically analyzed and compared with experimental results. First, strain relaxation induced by ion implantation and annealing, considering dislocation loop punching and loop interactions with interfaces/surfaces is discussed. A flexible curved dislocation model is used to determine the relation of critical layer thickness with strain/stress. Specific critical conditions to be fulfilled, at both the start and end of the relaxation, are discussed by introducing a quality parameter for efficient strain relaxation, defined as the ratio of real to ideal critical thickness versus strain/stress. The anisotropy of the resolved shear stress is discussed for (001) and (011) crystal orientations in comparison with the experimentally observed anisotropy of strain relaxation for Si/SiGe heterostructures.