Scanning electron and polarization microscopy study of the variability and character of hollow macro-defects in silicon carbide wafers

Presser, Volker; Loges, Anselm; Nickel, Klaus G.

doi:10.1080/14786430802243865

Cited by 11 publications

(16 citation statements)

References 44 publications

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“…Figure 7 depicts a radialite (∅137 μm) that has formed around a≈1 μm small micropipe (hollow‐core dislocation defect; cf. Presser et al 29 ) and which has already undergone the transition towards globulite formation starting at the center. There is no significant influence on the oxidation rate by the presence of such a small pipe; however, it has acted as a crystallization center.…”

Section: Resultsmentioning

confidence: 99%

Microstructural Evolution of Silica on Single‐Crystal Silicon Carbide. Part I: Devitrification and Oxidation Rates

Presser

Loges

Hemberger

et al. 2009

Journal of the American Ceramic Society

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Dry thermal oxidation of single‐crystal silicon carbide (6H‐SiC) at 1400°C in low‐water oxygen using an alumina tube furnace initially yields a predominantly vitreous oxide scale. After 28 h, approximately one quarter of the oxide scale's surface becomes crystalline, with disk‐like cristobalite aggregates (radialites) statistically distributed within the vitreous matrix. Crystalline areas were found to be thinner than vitreous regions using optical microscopy and atomic force microscopy/hydrofluoric acid (AFM/HF)‐etching analysis, providing evidence for different oxidation rates of SiC covered by vitreous silica and cristobalite. As the bulk oxide scale continues to grow during devitrification, the radialites assume their characteristic morphology with a deepened center. Line profiles of the oxide scale's thickness across radialites obtained from AFM/HF etching were used to determine the oxidation rate of SiC covered by crystalline silica and the crystallisation rate applying a two‐stage parabolic equation. As a result, it was found that the parabolic rate‐constant Bvitreous is ≈4.2 times larger than the corresponding rate‐constant in crystalline areas (Bcristobalite), suggesting similar differences in effective oxygen diffusion coefficients. For the crystallization rate ν, we determined a value of 1.5±0.1 μm/h.

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Section: Resultsmentioning

confidence: 99%

Microstructural Evolution of Silica on Single‐Crystal Silicon Carbide. Part I: Devitrification and Oxidation Rates

Presser

Loges

Hemberger

et al. 2009

Journal of the American Ceramic Society

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“…The elastic energy of a crystal-growth-related super dislocation is reduced if it forms a hollow core screw dislocation, i.e., a Volterra dislocation (Volterra 1907). Hollow core dislocations occur in SiC (Vetter and Dudley 2001; Presser et al 2008) and in steroid (Stoica et al 2007) crystals, the former having diameters larger than 10 µm and the latter 100 nm. Hollow core dislocation sources for spiral crystal growth were seen in inorganic calcite (Hillner et al 1992).…”

Section: Discussionmentioning

confidence: 99%

Structure of first- and second-stage mineralized elements in teeth of the sea urchin Lytechinus variegatus

Robach

Stock

Veis

2009

Journal of Structural Biology

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Microstructure of the teeth of the sea urchin Lytechinus variegatus was investigated using optical microscopy, SEM (scanning electron microscopy) and SIMS (secondary ion mass spectroscopy). The study focused on the internal structure of the first-stage mineral structures of high Mg calcite (primary, secondary and carinar process plates; prisms) and on morphology of the columns of second-stage mineral (very high Mg calcite) that cement the first-stage material together. Optical micrographs under polarized light revealed contrast in the centers (midlines) of carinar process plates and in prisms in polished sections; staining of primary and carinar process plates revealed significant dye uptake at the plate centers. Demineralization with and without fixation revealed that the midlines of primary and carinar process plates (but not secondary plates) and the centers of prisms differed from the rest of the plate or prism, and SIMS showed proteins concentrated in these plate centers. SEM was used to study the morphology of columns, the fracture surfaces of mature teeth and the 3D morphology of prisms. These observations of internal structures in plates and prisms offer new insight into the mineralization process and suggest an important role for protein inclusions within the first-stage mineral. Some of the 3D structures not reported previously, such as twisted prisms and stacks of carinar process plates with nested wrinkles, may represent structural strengthening strategies.

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“…Typical defect dimensions of voids are several 10s or even 100s of micrometer laterally and 10s of micrometer axially, while pipes have typical diameters of 10s of nanometer up to few micrometer with a depth in the millimeter‐range. In contrast to mechanically introduced scratches the surrounding area of these defects is perfectly crystalline and in case of voids in a relaxed state 11 . Therefore, no accelerated oxidation due to special stress or surface states of SiC must be taken into account.…”

Section: Resultsmentioning

confidence: 99%

“…Both influences are discussed in the light of globulite formation. Regarding the influence of defects, we studied hollow‐core defects (pipes and voids), that are frequently found in SiC wafers 11 …”

Section: Introductionmentioning

confidence: 99%

Microstructural Evolution of Silica on Single Crystal Silicon Carbide. Part II: Influence of Impurities and Defects

Presser¹,

Loges²,

Wirth³

et al. 2009

Journal of the American Ceramic Society

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Passive oxidation of single crystal silicon carbide (6H–SiC) resulted in the formation of a vitreous silica layer which crystallized gradually at temperatures near 1300°–1400°C. During this process, statistically distributed devitrification centers appeared and disk‐like aligned crystal plates (radialites) formed. The crystallization process did not necessarily start at structural defects although these often act as areas of preferred nucleation. A second structural transition from disk‐like radialites to small crystalline spheres (globulites) was not connected to structural defects but a consequence of the presence of impurities. Alkaline and earth‐alkaline elements are common contaminations within the atmospheres of typical furnaces fitted with alumina tubes. Globulite formation was a process of recrystallization catalyzed by an impurity‐related melt formed on top of the devitrified areas. Crystallization caused exsolution of reaction gas and local impurity enrichments as the solubility for these phases is much higher in the devitrifying vitreous silica matrix. Both clean and impurity‐loaded oxidation produced specific morphologies of scales and interfaces.

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Scanning electron and polarization microscopy study of the variability and character of hollow macro-defects in silicon carbide wafers

Cited by 11 publications

References 44 publications

Microstructural Evolution of Silica on Single‐Crystal Silicon Carbide. Part I: Devitrification and Oxidation Rates

Microstructural Evolution of Silica on Single‐Crystal Silicon Carbide. Part I: Devitrification and Oxidation Rates

Structure of first- and second-stage mineralized elements in teeth of the sea urchin Lytechinus variegatus

Microstructural Evolution of Silica on Single Crystal Silicon Carbide. Part II: Influence of Impurities and Defects

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