Dry thermal oxidation of a graded SiGe layer

Lim, Young Soo; Jeong, Jong Seok; Lee, Jun Young; Kim, HoSung; Shon, H. K.; Kim, H. K.; Moon, D. W.

doi:10.1063/1.1415373

Cited by 19 publications

(5 citation statements)

References 18 publications

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“…Such concentration gradients are typically characterized by a Ge-rich region adjacent to the SiO 2 growth front and are variously referred to as a pile-up region, snow plow effect, or germanium-rich layer (GRL). The pile-up effect, resulting from dry oxidation of SiGe, has been reported to occur in numerous publications, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] but these observations are frequently limited to the acknowledgment of the existence of a pile-up layer. Furthermore, the reports do not provide sufficient information to understand how modification of the oxidation conditions may lead to variations in the profile of Ge concentration in the SiGe.…”

Section: Introductionmentioning

confidence: 99%

Ge redistribution in SiO2/SiGe structures under thermal oxidation: Dynamics and predictions

Long

Azarov

Kløw

et al. 2012

Journal of Applied Physics

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Several fundamental aspects of the oxidation-induced redistribution of Ge in thin films of SiGe are studied. This includes the incorporation of Ge into the oxide and the formation of what is alternatively referred to as pileup , snow-plow, or a germanium-rich layer. Experimental data from the present work shows longer oxidation times leading to an increase of Ge content in the pileup region and eventually creating a single high Ge content pileup layer by entirely consuming the initial SiGe layer. The pileup effect was shown to occur at the oxidation interface, with the highest Ge content occurring at the same interface. For a given oxide thickness, the redistribution of Ge and the formation of a pileup region was shown experimentally to be independent of temperature in the range between 800 C and 1000 C. Simulations using common models for the oxidation of Si and diffusion of Si in SiGe indicate that temperature does have an influence on the composition of the pileup layer, though the range of achievable compositions is limited. The flux of Si due to diffusion of Si in SiGe relative to the oxidation-induced flux of Si out of the SiGe is integral to the formation and dimensions of a pileup region. Two predictive relations were derived for describing the dynamics of oxidation of SiGe. The first relation is given for determining the pileup layer thickness as a function of oxide thickness and the composition of the pileup layer. The second relation assumes a limited supply of Si and is for determination of the minimum initial thickness of a SiGe layer to avoid oxidation of Ge. The validity of these equations was confirmed experimentally by RBS and XPS data from the present work. The proposed models may be used in nanostructuring of thin films of SiGe by oxidation and in the design of core-shell structures and transistors. This is all done with a focus on oxidation of epitaxial thin films (< 100 nm) of Si 1-X Ge X in dry O 2 at 1 atm between 800 C and 1000 C. V

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Section: Introductionmentioning

confidence: 99%

Ge redistribution in SiO2/SiGe structures under thermal oxidation: Dynamics and predictions

Long

Azarov

Kløw

et al. 2012

Journal of Applied Physics

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“…Although the oxidation of Si is described by the well established Deal-Grove 6 and Massoud 7 models, the oxidation of SiGe is not as well characterized. 8,15,[20][21][22][23][24][25][26][27][28][29][30][31][32][33] Despite the work that has been done to study oxidation of SiGe, a lack of consensus remains regarding oxidation rates for SiGe as compared to that of Si. 15 Several models have been proposed to describe the oxidation processes in SiGe, 11,[16][17][18][19] all of which consider the relative diffusion of O in SiO 2 and that of Si in SiGe and Ge.…”

Section: Introductionmentioning

confidence: 99%

Ge concentrations in pile-up layers of sub-100-nm SiGe films for nano-structuring by thermal oxidation

Long

Galeckas

Kuznetsov

2012

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The data and analysis presented herein aims to facilitate the design and manufacture of SiGe based nanostructures and devices by describing the enhancement of Ge concentration in sub-100-nm thin films of SiGe by dry thermal oxidation. Thin films of SiGe were restructured by using thermal oxidation induced self-organization of Si and Ge atoms to create a layer of enhanced Ge concentration. The dry thermal oxidations were carried out at temperatures between 800 C and 1000 C. The influence of temperature on the Ge content at the oxidation front, as measured by x-ray diffraction, is examined and supported by simulation results. A model for determination of the Ge content in the pile-up layer is presented along with appropriate values for the activation energy and pre-exponential constant for diffusion of Si in Si 1-X Ge X . This model may also be used for determination of the diffusivity of Si in Si 1-X Ge X by fitting the model results to the measured Ge concentration in the pile-up layer. It is observed that the Ge content at the oxidation front is a function of temperature and varies linearly between 64% at 800 C and 36% at 1000 C. However, the Ge content is largely independent of oxide thickness and the Ge content in the initial SiGe layer. When the Ge concentration at the oxidation front is considered, the experimental results presented here indicate that the oxidation rates of SiGe closely match those of Si and provide evidence that the presence of Ge in very thin films of SiGe does not lead to enhanced or retarded oxidation rates as compared to Si.

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“…One of the most promising techniques for obtaining such high quality relaxed SiGe layers is oxidation-induced Ge condensation process under high oxidation temperature [4][5][6]. In this method, Ge atoms accumulate near the oxide interface but at the same time also diffuse towards the substrate during oxidation process.…”

Section: Introductionmentioning

confidence: 99%