Evolution of Basal Plane Dislocations during 4H-SiC Epitaxial Growth

2008 ◽  
Vol 600-603 ◽  
pp. 317-320 ◽  
Author(s):  
Robert E. Stahlbush ◽  
Brenda L. VanMil ◽  
Kendrick X. Liu ◽  
Kok Keong Lew ◽  
Rachael L. Myers-Ward ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Basal Plane ◽  
Gas Flow ◽  
Epitaxial Layers ◽  
Half Loop ◽  
Edge Dislocations

The evolution of basal plane dislocations (BPDs) in 4H-SiC epitaxy during its growth is investigated by using two types of interrupted growth in conjunction with ultraviolet photoluminescence (UVPL) imaging of the dislocations. For the first, each epitaxial growth was stopped after 10-20 μm and a UVPL map was collected. For the second, changing the gas flow interrupted the growth and the BPDs were imaged at the end. The first sequence made it possible to track the formation of half-loop arrays and show that they arise from BPDs that glide perpendicular to the offcut direction. For both types, each interruption causes between 30 – 50% of the BPDs to be converted to threading edge dislocations (TEDs). This result suggests that using interrupted growth may be an alternate method to producing epitaxial layers with low BPD concentration.

A Pictorial Tracking of Basal Plane Dislocations in SiC Epitaxy

2010 ◽  
Vol 645-648 ◽  
pp. 271-276 ◽  
Author(s):  
Robert E. Stahlbush ◽  
Rachael L. Myers-Ward ◽  
Brenda L. VanMil ◽  
D. Kurt Gaskill ◽  
Charles R. Eddy
Keyword(s):  
Epitaxial Growth ◽  
Basal Plane ◽  
Reduction Process ◽  
Epitaxial Layers ◽  
In Situ Growth ◽  
Half Loop ◽  
Insight Into

The recently developed technique of UVPL imaging has been used to track the path of basal plane dislocations (BPDs) in SiC epitaxial layers. The glide of BPDs during epitaxial growth has been observed and the role of this glide in forming half-loop arrays has been examined. The ability to track the path of BPDs through the epitaxy has made it possible to develop a BPD reduction process for epitaxy grown on 8° offcut wafers, which uses an in situ growth interrupt and has achieved a BPD reduction of > 98%. The images also provide insight into the strong BPD reduction that typically occurs in epitaxy grown on 4° offcut wafers.

Investigation of In-Grown Dislocations in 4H-SiC Epitaxial Layers

2006 ◽  
Vol 527-529 ◽  
pp. 147-152 ◽  
Author(s):  
Kazutoshi Kojima ◽  
Tomohisa Kato ◽  
Satoshi Kuroda ◽  
Hajime Okumura ◽  
Kazuo Arai
Keyword(s):  
Epitaxial Growth ◽  
Epitaxial Layer ◽  
Basal Plane ◽  
Growth Conditions ◽  
Epitaxial Layers ◽  
Etch Pit Density ◽  
High Conversion Efficiency ◽  
Etch Pit ◽  
Edge Dislocations

We have investigated the generation of new dislocations during the epitaxial growth of 4H-SiC layers. Dislocations were mainly propagated from the substrate into the epitaxial layer. However, it was found that some amount of new threading edge dislocations (TEDs) and basal plane dislocations (BPDs) were generated during the epitaxial growth. The generation of those dislocations appeared to depend on the in-situ H2 etching conditions, not the epitaxial growth conditions. By optimizing in-situ H2 etching condition, we were able to effectively suppress the generation of new dislocations during epitaxial growth, and obtain 4H-SiC epitaxial layers which have the equivalent etch pit density (EPD) to the substrates. Our additional investigation of the conversion of BPDs to TEDs revealed that its efficiency similarly depends on in-situ H2 etching. We were able to obtain a high conversion efficiency of 97 % by optimizing the in-situ H2 etching conditions before epitaxial growth.

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%.

Turning of Basal Plane Dislocations during Epitaxial Growth on 4° Off-Axis 4H-SiC

2009 ◽  
Vol 615-617 ◽  
pp. 105-108 ◽  
Author(s):  
Rachael L. Myers-Ward ◽  
Brenda L. VanMil ◽  
Robert E. Stahlbush ◽  
S.L. Katz ◽  
J.M. McCrate ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Epitaxial Growth ◽  
Conversion Efficiency ◽  
Vapor Deposition ◽  
Basal Plane ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Epitaxial Layers ◽  
Basal Plane Dislocation ◽  
Edge Dislocations

Epitaxial layers were grown on 4° off-axis 4H-SiC substrates by hot-wall chemical vapor deposition. The reduced off-cut angle resulted in lower basal plane dislocation (BPD) densities. The dependence of BPD reduction on growth conditions was investigated using ultraviolet photoluminescence (UVPL) imaging. With this method, it was found that the dislocations were converting to threading edge dislocations throughout the thickness of the film. A high (≥ 97%) conversion efficiency was found for all films grown with this orientation. A conversion of 100% was achieved for several films without pre-growth treatments or growth interrupts.

Glide of threading edge dislocations after basal plane dislocation conversion during 4H–SiC epitaxial growth

2015 ◽  
Vol 418 ◽  
pp. 7-14 ◽  
Author(s):  
Mina Abadier ◽  
Haizheng Song ◽  
Tangali S. Sudarshan ◽  
Yoosuf N. Picard ◽  
Marek Skowronski
Keyword(s):  
Epitaxial Growth ◽  
Basal Plane ◽  
Basal Plane Dislocation ◽  
Edge Dislocations

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.

Epitaxial Growth of SiC in a Vertical Multi-Wafer CVD System: Already Suited as Production Process?

1999 ◽  
Vol 572 ◽  
Author(s):  
Roland Rupp ◽  
Christian Hecht ◽  
Arno Wiedenhofer ◽  
Dietrich Stephani
Keyword(s):  
Epitaxial Growth ◽  
Gas Flow ◽  
Defect Density ◽  
Schottky Diodes ◽  
Impurity Level ◽  
Thickness Variation ◽  
Epitaxial Layers ◽  
Growth Step ◽  
Low Leakage ◽  
Low Leakage Current

ABSTRACTResults about a new CVD system suited for epitaxial growth on six 2 inch SiC-wafers at a time are presented. Excellent gas flow stability is achieved for this new reactor type as shown by in- situ observations of the gas flow dynamics in the reactor chamber. These experimental results agree favorably with numerical process simulation results.The epitaxial layers grown in the multi-wafer system so far show a by an order of magnitude higher background impurity level (≤1015 cm−3) as reported previously for layers grown in single-wafer systems by the authors and other groups (≤ 1014 cm−3). On the other hand, the doping homogeneity achieved until today is very encouraging. The variation on a 2 inch wafer is less than ± 20% at about 1*1016 cm−3. The wafer to wafer variation of the average doping value both within a run and from run to run is within 15 %. The reproducibility and uniformity of the layer thickness is even better (total thickness variation ≤5% on a 2 inch wafer). The surface of the epitaxial layers is very smooth with a typical growth step height of 0.5 nm (4H, 8° off orientation). First measurements on Schottky diodes build on these layers show low leakage current values indicating low point defect density in the epitaxial layers.

Basal Plane Dislocations from Inclusions in 4H-SiC Epitaxy

2014 ◽  
Vol 778-780 ◽  
pp. 309-312 ◽  
Author(s):  
Robert E. Stahlbush ◽  
Nadeemullah A. Mahadik ◽  
Michael J. O'Loughlin
Keyword(s):  
Epitaxial Growth ◽  
Basal Plane ◽  
Large Fraction ◽  
Local Cluster ◽  
Edge Dislocations ◽  
Drift Layer

Suppression of basal plane dislocations (BPDs) from critical epitaxial drift layer has occurred mainly by converting BPDs in the substrate into threading edge dislocations before the BPDs enter the drift layer. As optimized epitaxial growth has produced drift layers free of BPDs originating from the substrate over a large fraction of the wafer, other sources of BPDs have become important. One source of BPDs introduced during epitaxial growth is from inclusions, which mainly consist of misoriented 4H-SiC. Inclusions are surrounded by a local cluster of BPDs and in thick, low-BPD epitaxy the outermost BPDs glide centimeters from the inclusion forming a much larger damaged area. The details of BPD migration from inclusions are discussed.

New SiC Epitaxial Growth Process with up to 100% BPD to TED Defect Conversion on 150mm Hot-Wall CVD Reactor

2019 ◽  
Vol 963 ◽  
pp. 123-126
Author(s):  
Tobias Höchbauer ◽  
Christian Heidorn ◽  
Nikolaos Tsavdaris
Keyword(s):  
Epitaxial Growth ◽  
Epitaxial Layer ◽  
Basal Plane ◽  
Growth Process ◽  
High Growth ◽  
High Growth Rate ◽  
Layer Growth ◽  
Structural Defects ◽  
Epitaxial Layers ◽  
Basal Plane Dislocation

The future challenges for SiC device technology are cost reduction and increased reliability. A key point to achieve that is the increase of yield during epitaxial layer growth through the reduction of structural defects (such as basal plane dislocations and triangle defects), an increased thickness and doping uniformity, and a high growth rate. Despite significant advancements in SiC epitaxial growth technology, it still constitutes a big challenge to find the optimum working point at which all those requirements are fulfilled. By implementing a new epitaxial layer growth process, we are able to grow basal plane dislocation free epitaxial layers, while the density of other structural defects remains low. Additionally, intra-wafer thickness and doping uniformities of the epitaxial layers are further improved.

Current Status of the Quality of 4H-SiC Substrates and Epilayers for Power Device Applications

MRS Advances ◽  
2016 ◽  
Vol 1 (2) ◽  
pp. 91-102 ◽  
Author(s):  
M. Dudley ◽  
H. Wang ◽  
Jianqiu Guo ◽  
Yu Yang ◽  
Balaji Raghothamachar ◽  
...  
Keyword(s):  
Relaxation Process ◽  
Epitaxial Growth ◽  
Driving Force ◽  
Lattice Parameter ◽  
Current Status ◽  
Concentration Difference ◽  
Before And After ◽  
Half Loop ◽  
Device Applications ◽  
Edge Dislocations

ABSTRACTInterfacial dislocations (IDs) and half-loop arrays (HLAs) present in the epilayers of 4H-SiC crystal are known to have a deleterious effect on device performance. Synchrotron X-ray Topography studies carried out on n-type 4H-SiC offcut wafers before and after epitaxial growth show that in many cases BPD segments in the substrate are responsible for creating IDs and HLAs during CVD growth. This paper reviews the behaviors of BPDs in the substrate during the epitaxial growth in different cases: (1) screw-oriented BPD segments intersecting the surface replicate directly through the interface during the epitaxial growth and take part in stress relaxation process by creating IDs and HLAs (Matthews-Blakeslee model [1] ); (2) non-screw oriented BPD half loop intersecting the surface glides towards and replicates through the interface, while the intersection points convert to threading edge dislocations (TEDs) and pin the half loop, leaving straight screw segments in the epilayer and then create IDs and HLAs; (3) edge oriented short BPD segments well below the surface get dragged towards the interface during epitaxial growth, leaving two long screw segments in their wake, some of which replicate through the interface and create IDs and HLAs. The driving force for the BPDs to glide toward the interface is thermal stress and driving force for the relaxation process to occur is the lattice parameter difference at growth temperature which results from the doping concentration difference between the substrate and epilayer.

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