Large-Area Mapping of Dislocations in 4H-SiC from Carbon-Face (000-1) by Using Vaporized KOH Etching near 1000 °C

2013 ◽  
Vol 740-742 ◽  
pp. 829-832
Author(s):  
Yong Zhao Yao ◽  
Yukari Ishikawa ◽  
Koji Sato ◽  
Yoshihiro Sugawara ◽  
Katsunori Danno ◽  
...  
Keyword(s):  
Basal Plane ◽  
Chemical Etching ◽  
Sample Thickness ◽  
Large Area ◽  
Inexpensive Method ◽  
Etching Technique ◽  
Screw Dislocations ◽  
Wafer Thickness ◽  
Edge Dislocations ◽  
Koh Etching

To solve the problem that no preferential chemical etching is available for dislocation revelation from the carbon-face (C-face) of 4H-SiC, a novel etching technique using vaporized KOH has been developed. It was found that this etching technique can reveal the three commonly found dislocation types, i.e., threading screw dislocations (TSDs), threading edge dislocations (TEDs) and basal plane dislocations (BPDs) as large hexagonal, small hexagonal and triangular, respectively. Centimeter-scale dislocation mapping has been obtained, and the pit positions on the C-face were compared with those on the Si-face, to study the dislocation propagation behaviors across the sample thickness. We have found one-to-one correlation for nearly 96% of the TSDs, indicating a dominant proportion of TSDs penetrate the whole wafer thickness. The vaporized KOH etching technique has provided an effective and inexpensive method of making inch-scale mapping of dislocation distribution for the C-face epitaxial and bulky 4H-SiC.

Dislocation Revelation in Highly Doped N-Type 4H-SiC by Molten KOH Etching with Na2O2 Additive

2011 ◽  
Vol 679-680 ◽  
pp. 290-293 ◽  
Author(s):  
Yong Zhao Yao ◽  
Yukari Ishikawa ◽  
Yoshihiro Sugawara ◽  
Hiroaki Saitoh ◽  
Katsunori Danno ◽  
...  
Keyword(s):  
Electron Concentration ◽  
Basal Plane ◽  
Wet Etching ◽  
Etch Pits ◽  
Screw Dislocations ◽  
Edge Dislocations ◽  
Koh Etching

We have proposed a new wet etching recipe using molten KOH and Na2O2 as the etchant (“KN etching”) for dislocation revelation in highly doped n-type 4H-SiC (n+-4H-SiC). Threading screw dislocations (TSDs) and threading edge dislocations (TEDs) have been clearly revealed as hexagonal etch pits differing in pit sizes, and basal plane dislocations (BPDs) as seashell-shaped pits. This new etching recipe has provided a solution to the problem that conventional KOH etching is not effective for dislocation identification in 4H-SiC if the electron concentration is high (>mid-1018 cm-3). We have investigated the effect of SiC off-cut angle on KN etching and it has been shown that the “KN etching” is applicable for the n+-SiC substrate with off-angle from 0o to 8o.

New Separation Method of Threading Dislocations in 4H-SiC Epitaxial Layer by Molten KOH Etching

2011 ◽  
Vol 679-680 ◽  
pp. 298-301 ◽  
Author(s):  
T. Katsuno ◽  
Y. Watanabe ◽  
Fujiwara Hirokazu ◽  
Masaki Konishi ◽  
Takeo Yamamoto ◽  
...  
Keyword(s):  
Epitaxial Layer ◽  
Basal Plane ◽  
Separation Method ◽  
New Method ◽  
Threading Dislocations ◽  
Screw Dislocations ◽  
Etch Pit ◽  
Almost All ◽  
Edge Dislocations ◽  
Koh Etching

A new method for the separation of threading screw dislocations (TSD) and threading edge dislocations (TED) in a 4H-SiC epitaxial layer is proposed by measurement of the etch pit angles. The etch pit angles of the TSDs and TEDs were 28±3 and 18±3°, respectively. In the case of etch pit depths within the epitaxial layer, the values were almost constant. Almost all of the TSDs were converted from basal plane dislocations (BPDs) at the epitaxial layer/substrate interface.

Effects of Different Defect Types on the Performance of Devices Fabricated on a 4H-SiC Homoepitaxial Layer

2006 ◽  
Vol 911 ◽  
Author(s):  
Hui Chen ◽  
Balaji Raghothamachar ◽  
William Vetter ◽  
Michael Dudley ◽  
Y. Wang ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Basal Plane ◽  
Schottky Contacts ◽  
Device Performance ◽  
Hollow Core ◽  
Screw Dislocations ◽  
Burgers Vector ◽  
Edge Dislocations ◽  
Sic Wafer ◽  
Koh Etching

AbstractAn 8° off-axis 4H-SiC wafer with circular Schottky contacts fabricated on a CVD grown 4H-SiC homoepitaxial layer was studied to investigate the influence of various defects, including small (closed-core) screw dislocations (Burgers vector of 1c or 2c), hollow-core (micropipes; Burgers vector larger than 2c), threading edge dislocations (from conversion of basal plane dislocations from the substrate into the epilayer), grain boundaries and triangular defects, on the device performance in the form of breakdown voltages. The defects were examined using synchrotron white beam x-ray topography (SWBXT) based techniques and molten KOH etching. The devices commonly contained basal plane dislocations, small screw dislocations and threading edge dislocations, the latter two of which could give rise to low breakdown voltages for the devices. In addition, less commonly observed defects such as micropipes, grain boundaries and triangular defects are much more destructive to device performance than closed-core screw dislocations and threading edge dislocations.

Dislocations Propagation Study Trough High-Resolution 4H-SiC Substrate Mapping

2019 ◽  
Vol 963 ◽  
pp. 276-279 ◽  
Author(s):  
Ruggero Anzalone ◽  
Nicolò Piluso ◽  
Andrea Severino ◽  
Simona Lorenti ◽  
Giuseppe Arena ◽  
...  
Keyword(s):  
High Resolution ◽  
Epitaxial Layer ◽  
Basal Plane ◽  
Stacking Faults ◽  
Screw Dislocations ◽  
Density Maps ◽  
Dislocations Density ◽  
Koh Etching

In this work a deep investigation of the dislocation on 4H-SiC substrate has been shown. The dislocation intersecting the surface were enhanced by KOH etching at 500 deg. C. performed on whole 6 inches substrate. A comparison between basal plane dislocations and threading screw dislocations in the substrate with the defects in the epitaxial layer (mainly stacking faults and carrots) was performed. The comparison between shows a correlation between basal plane dislocations density and stacking faults density maps.

Nucleation of c-Axis Screw Dislocations at Substrate Surface Damage during 4H-Silicon Carbide Homo-Epitaxy

2010 ◽  
Vol 645-648 ◽  
pp. 295-298 ◽  
Author(s):  
Michael Dudley ◽  
Ning Zhang ◽  
Yu Zhang ◽  
Balaji Raghothamachar ◽  
Edward K. Sanchez
Keyword(s):  
Basal Plane ◽  
Opposite Sign ◽  
Substrate Surface ◽  
Surface Damage ◽  
Dislocation Nucleation ◽  
Screw Dislocations ◽  
Basal Plane Dislocation ◽  
Residual Damage ◽  
Step Flow Growth ◽  
Edge Dislocations

Observations of dislocation nucleation occurring at substrate surface scratches during 4H-SiC CVD homoepitaxial growth are reported. Sub-surface residual damage associated with the scratches is observed to act as nucleation sites for basal plane dislocations (BPDs), threading edge dislocations (TEDs) and threading screw dislocations (TSDs) in the epilayer. TEDs and BPDs replicate from the surface intersections of basal plane dislocation half-loops injected into the substrate surface. A model for the nucleation mechanism of TSDs, which nucleate in opposite sign pairs, is presented which involves overgrowth of surface indentations associated with the scratch during step flow growth. Atomic steps which approach these local surface indentations can collapse creating pairs of opposite sign screw dislocations which have Burgers vector magnitude equal to the magnitude of the step disregistry created during the collapse.

Characterization and Reduction of Defects in 4H-SiC Substrate and Homo-Epitaxial Wafer

2020 ◽  
Vol 1004 ◽  
pp. 387-392 ◽  
Author(s):  
Long Yang ◽  
Li Xia Zhao ◽  
Hui Wang Wu ◽  
Yafei Liu ◽  
Tuerxun Ailihumaer ◽  
...  
Keyword(s):  
Basal Plane ◽  
Chemical Vapor ◽  
Vapor Transport ◽  
Etching Time ◽  
X Ray ◽  
Half Loop ◽  
Dislocation Behavior ◽  
Edge Dislocations ◽  
Defect Morphology ◽  
Koh Etching

4H-SiC substrates and homo-epitaxial layers were obtained using the traditional methods of physical vapor transport and chemical vapor deposition. Defect morphology has been studied using both Synchrotron White Beam X-ray Topography and Monochromatic Beam X-ray Topography. Molten KOH etching method was adopted to further investigate the dislocation behavior mechanisms. Deflected dislocations were observed at the periphery regions in both substrate and epitaxial wafers. 3C polytypes and half loop arrays were observed in the 4H-SiC epitaxial wafer. It is also found that the majority of basal plane dislocations are converted to threading edge dislocations in the epitaxial wafer samples. The proportion of BPD to TED conversion depends on the surface step morphology and growth mode in epitaxial growth which in turn depends on the C/Si ratio. By the optimization of etching time prior to epitaxy and C/Si ratio, high-quality epitaxial wafers with extremely low basal plane dislocations densities (＜0.1 cm-2) was obtained.

Dislocation Analysis in Highly Doped n-Type 4H-SiC by Using Electron Beam Induced Current and KOH+Na2O2 Etching

2011 ◽  
Vol 679-680 ◽  
pp. 294-297 ◽  
Author(s):  
Yong Zhao Yao ◽  
Yoshihiro Sugawara ◽  
Yukari Ishikawa ◽  
Hiroaki Saitoh ◽  
Katsunori Danno ◽  
...  
Keyword(s):  
Electron Beam ◽  
Basal Plane ◽  
Wet Etching ◽  
Induced Current ◽  
Screw Dislocations ◽  
Electron Beam Induced Current ◽  
Edge Dislocations

Dislocations in highly doped n-type 4H-SiC (n+-SiC, n>1019 cm-3) substrate have been studied by means of electron beam induced current (EBIC). Ni/n-SiC/n+-SiC/Al structure was fabricated in order to simultaneously observe the dislocations in n-SiC epilayer and n+-SiC substrate. We have found that dark dots in the EBIC image correspond to threading screw dislocations (TSDs) and threading edge dislocations (TEDs) with the former being relatively darker. Short dark lines along off-cut are attributed to basal plane dislocations (BPDs) in the epilayer; and the randomly oriented long dark lines are caused by the BPDs in the substrate. The classification of the dislocations by EBIC has been examined by wet etching in KOH+Na2O2.

Origin Analyses of Trapezoid-Shape Defects in 4-Deg.-off 4H-SiC Epitaxial Wafers by Synchrotron X-Ray Topography

2014 ◽  
Vol 778-780 ◽  
pp. 374-377 ◽  
Author(s):  
Tamotsu Yamashita ◽  
Hirofumi Matsuhata ◽  
Yoshihiko Miyasaka ◽  
Kenji Momose ◽  
Takayuki Sato ◽  
...  
Keyword(s):  
Basal Plane ◽  
Surface Defects ◽  
Epitaxial Film ◽  
Negative Impact ◽  
Film Surface ◽  
Dislocation Loops ◽  
Screw Dislocations ◽  
X Ray ◽  
Mos Devices ◽  
Edge Dislocations

The trapezoid-shape defects are one of the most common surface defects on current 4H-SiC epitaxial film surface since they give rise negative impact for MOS-devices. We have investigated structures and origins of the defects. It is discovered that the possible origins of the trapezoid-shape defects are basal plane dislocations (BPDs), threading edge dislocations (TEDs), threading screw dislocations (TSDs),and the short dislocation loops introduced under scratches.

Observation of Misfit Dislocations Introduced by Epi-Layer Growth on 4H-SiC

2008 ◽  
Vol 600-603 ◽  
pp. 309-312 ◽  
Author(s):  
Hirofumi Matsuhata ◽  
Hirotaka Yamaguchi ◽  
Ichiro Nagai ◽  
Toshiyuki Ohno ◽  
Ryouji Kosugi ◽  
...  
Keyword(s):  
Basal Plane ◽  
Grazing Incidence ◽  
Lattice Parameter ◽  
Layer Growth ◽  
Misfit Dislocations ◽  
Screw Dislocations ◽  
Incidence Geometries ◽  
The Difference ◽  
Edge Dislocations ◽  
Monochromatic Synchrotron

4H-SiC substrate wafers with epi-layers were observed using monochromatic synchrotron X-ray topography in grazing incidence geometries, to investigate the defects in the epi-layer. Misfit dislocations with b=+1/3[11 2 0] caused by the difference in lattice parameter between the epi-layer and the substrate were observed. The misfit dislocations are located near the interface as edge dislocations, and appear at the top surface as screw dislocations on basal planes. It was observed that more than half of them were introduced from the growing epi-layer surface. The misfit dislocations and some screw dislocations with b=+1/3[11 2 0] are observed to remain as basal plane dislocations at the surface, while other basal plane dislocations were converted to threading edge dislocations in the epi-layer.

Conversion of Basal Plane Dislocations to Threading Edge Dislocations in Growth of Epitaxial Layers on 4H-SiC Substrates with a Vicinal Off-Angle

2014 ◽  
Vol 778-780 ◽  
pp. 99-102 ◽  
Author(s):  
Keiko Masumoto ◽  
Sachiko Ito ◽  
Hideto Goto ◽  
Hirotaka Yamaguchi ◽  
Kentaro Tamura ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Edge Dislocation ◽  
Basal Plane ◽  
Conversion Ratio ◽  
Epitaxial Layers ◽  
Etch Pits ◽  
X Ray ◽  
Basal Plane Dislocation ◽  
Edge Dislocations ◽  
Koh Etching

We have investigated a conversion of basal plane dislocation (BPD) to threading edge dislocation (TED) in growth of epitaxial layers (epi-layers) on 4H-SiC vicinal substrates with an off-angle of 0.85° at low C/Si ratio of 0.7 by using deep KOH etching and X-ray topography observations. Deep KOH etching indicated that BPDs in the substrates converted to TEDs in the epi-layers. X-ray topography observations suggested that the conversion occurred during epitaxial growth when the thickness of epi-layers was less than 1.5 μm. We found that the conversion ratio obtained from counting deep KOH etch pits was over 99%.

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