Strain relaxation mechanism in SiGe-on-insulator fabricated by Ge condensation

Di, Zengfeng; Huang, Anping; Chu, Paul K.; Zhang, Miao; Liu, Weili; Zhang, Song; Luo, Suhua; Chenglu, Lin

doi:10.1016/j.jcrysgro.2005.04.031

Cited by 11 publications

(6 citation statements)

References 20 publications

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“…Results from the AFM analysis of sample oxidized 60 minutes are given in Figure 7. The Rms value of 1.47 nm measured on 10 μm square is close to data reported in literature (1,5,10). The cross-hatch pattern on Figure 7 is commonly observed on the surface of relaxed or partially relaxed SGOI layers because of misfit dislocations (1,10).…”

Section: Resultssupporting

confidence: 90%

“…According to the literature such a complete oxidation is not likely to be achieved after 60 min. Data reported earlier reveal that this is achieved usually after > 180 min dry oxidation at temperatures >900 o C [1,3,5,6]. Additional measurements done on 3 different points on the same sample, as shown on Figure 1b revealed that the shape and relative intensity of the Ge-Ge signal varies significantly indicating the formation of non-homogeneous layer.…”

Section: Resultsmentioning

confidence: 53%

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The Challenges of Ge-Condensation Technique

Terzieva¹,

Caymax²,

Souriau³

et al. 2006

ECS Trans.

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Ultra-thin SiGe films on insulator with high Ge fraction were fabricated through Ge condensation. To achieve that strained Si 0.75 Ge 0.25 layers were grown epitaxially on SOI wafers and oxidized in O 2 at 1150 o C for various times. Raman measurements and X-TEM revealed the importance of purity of oxidation ambient for the oxidation process. Traces of moisture in the oxygen flux accelerate the process causing a switch from dry to wet oxidation mechanism, leading to complete oxidation of the starting layer in only 1 hour. The crystal quality and overall uniformity of such layers however is poor. The use of 100% dry oxygen provides the necessary control over the oxidation process. This allowed relaxed SiGe layers with concentration of Ge up to 45% and higher to be obtained. X-TEM indicated good crystalline quality and uniform layers with no threading dislocations or other defects introduced during oxidation.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 53%

The Challenges of Ge-Condensation Technique

Terzieva¹,

Caymax²,

Souriau³

et al. 2006

ECS Trans.

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show abstract

“…16 This implies that during the condensation process, a high level of stress is generated in the SiGe layer. This stress can be relaxed by different mechanisms: compliance of the BOX, 17 generation of dislocations, 18,19 or roughening of the SiGe layer. 20 The creation of defects may have an important impact on the final electrical transport properties of the SGOI or GeOI layers.…”

mentioning

confidence: 99%

High-Hole-Mobility Silicon Germanium on Insulator Substrates with High Crystalline Quality Obtained by the Germanium Condensation Technique

Souriau

Nguyen

Augendre

et al. 2009

J. Electrochem. Soc.

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Thin SiGe-on-insulator (SGOI) substrates with Ge content varying between 42 and 93% were produced by the Ge condensation technique and full structural characterization was carried out. In a second step, the electrical properties of these substrates were analyzed by the pseudo metal-oxide semiconductor field-effect transistor technique which allowed determination of the carrier low-field mobilities, as well as the density of fixed charges in the buried oxide (BOX) and the density of interface traps at the BOX-SiGe film interface. Optimization of intermediate anneals in argon during the condensation process made the production of high crystalline quality and high-mobility substrates possible (up to 400cm2normalV−1normals−1 for a 93% SGOI). Opposite trends were observed for holes and electrons: while the hole mobility increases with increasing Ge content, the electron mobility decreases. In addition, the density of interface traps and also the density of oxide charges were found to increase with increasing Ge content. Possible causes for this increase are discussed.

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“…In addition, strainrelaxation behavior of the SiGe layer during oxidation was not definitely clarified. Bedell et al 12 presented that the strain relaxation of the SiGe-on-insulator formed by high-temperature oxidation is dislocation-mediated and the behavior of relaxation was in agreement with equilibrium theory, while Di et al 13 attributed the strain relaxation of SiGe-on-insulator only to the compliant substrate without introducing dislocations. Terzieva 14 also found that no threading dislocations were introduced in the SiGe for strain relaxation during the oxidation processes.…”

mentioning

confidence: 84%

Oxidation Behavior of Strained SiGe Layer on Silicon Substrate in Both Dry and Wet Ambient

Cai

Zhang

et al. 2008

J. Electrochem. Soc.

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The oxidation behavior of a strained SiGe epitaxial layer on silicon substrate in both dry and wet ambient was investigated. We found that the oxide thickness at which oxidation saturation occurs increases with oxidation temperature and is larger for wet oxidation than dry oxidation at the same temperature, although Ge concentration at the oxidizing interface is much higher for wet oxidation. This observation shows that the oxidation saturation is not due to the thin, higher Ge-concentration layer at the oxidizing interface or the remaining strain of SiGe layer as reported previously. Different from the monotonous increase with oxidation time for the SiGe layer oxidized in dry oxygen, the degree of strain relaxation in the SiGe layer increases up to about 90% in a short time and then decreases slowly during wet oxidation at 1000°C. These results suggest that the expansion in volume due to the transformation of SiGe to oxide greatly contributes to the anomalous strain relaxation process for fast oxidation in wet ambient. In addition, higher density of threading dislocations was observed in the samples oxidized in wet ambient.

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Strain relaxation mechanism in SiGe-on-insulator fabricated by Ge condensation

Cited by 11 publications

References 20 publications

The Challenges of Ge-Condensation Technique

The Challenges of Ge-Condensation Technique

High-Hole-Mobility Silicon Germanium on Insulator Substrates with High Crystalline Quality Obtained by the Germanium Condensation Technique

Oxidation Behavior of Strained SiGe Layer on Silicon Substrate in Both Dry and Wet Ambient

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