scholarly journals Effect of Process Parameters on Dislocation Density in Thick 4H-SiC Epitaxial Layers Grown by Chloride-Based CVD on 4° Off-Axis Substrates

2014 ◽  
Vol 778-780 ◽  
pp. 159-162
Author(s):  
Milan Yazdanfar ◽  
Henrik Pedersen ◽  
Olof Kordina ◽  
Erik Janzén
Keyword(s):  
Dislocation Density ◽  
Process Parameters ◽  
Growth Temperature ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Etching Time ◽  
Epitaxial Layers ◽  
Basal Plane Dislocation ◽  
Koh Etching

The effect of process parameters such as growth temperature, C/Si ratio, etching time, and Si/H2ratio on dislocation density was investigated by performing KOH etching on 100 μm thick epitaxial layers grown on 4° off axis 4H-SiC substrates at various growth conditions by a chemical vapor deposition (CVD) process using a chloride-based chemistry to achieve growth rates exceeding 100 μm/h. We observe that the growth temperature and the growth rate have no significant influence on the dislocation density in the grown epitaxial layers. A low C/Si ratio increases the density of threading screw dislocations (TSD) markedly. The basal plane dislocation (BPD) density was reduced by using a proper in-situ etch prior to growth.

4H-SiC Homoepitaxial Growth on Vicinal-Off Angled Si-Face Substrate

2010 ◽  
Vol 645-648 ◽  
pp. 99-102 ◽  
Author(s):  
Kazutoshi Kojima ◽  
Sachiko Ito ◽  
Junji Senzaki ◽  
Hajime Okumura
Keyword(s):  
Surface Morphology ◽  
Epitaxial Growth ◽  
Growth Temperature ◽  
Growth Conditions ◽  
Step Bunching ◽  
Homoepitaxial Growth ◽  
Blocking Voltage ◽  
Basal Plane Dislocation ◽  
Epilayer Surface

We have carried out detailed investigations of 4H-SiC homoepitaxial growth on vicinal off-angled Si-face substrates. We found that the surface morphology of the substrate just after in-situ H2 etching was also affected by the value of the vicinal-off angle. Growth conditions consisting of a low C/Si ratio and a low growth temperature were effective in suppressing macro step bunching at the grown epilayer surface. We also demonstrated epitaxial growth without step bunching on a 2-inch 4H-SiC Si-face substrate with a vicinal off angle of 0.79o. Ni Schottky barrier diodes fabricated on an as-grown epilayer had a blocking voltage above 1000V and a leakage current of less than 5x10-7A/cm2. We also investigated the propagation of basal plane dislocation from the vicinal off angled substrate into the epitaxial layer.

Morphology Optimization of Very Thick 4H-SiC Epitaxial Layers

2013 ◽  
Vol 740-742 ◽  
pp. 251-254
Author(s):  
Milan Yazdanfar ◽  
Pontus Stenberg ◽  
Ian D. Booker ◽  
Ivan.G Ivanov ◽  
Henrik Pedersen ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Epitaxial Growth ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Epitaxial Layers ◽  
Power Devices ◽  
Chemical Vapor Deposition Reactor ◽  
Thick Layers

Epitaxial growth of about 200 µm thick, low doped 4H-SiC layers grown on n-type 8° off-axis Si-face substrates at growth rates around 100 µm/h has been done in order to realize thick epitaxial layers with excellent morphology suitable for high power devices. The study was done in a hot wall chemical vapor deposition reactor without rotation. The growth of such thick layers required favorable pre-growth conditions and in-situ etch. The growth of 190 µm thick, low doped epitaxial layers with excellent morphology was possible when the C/Si ratio was below 0.9. A low C/Si ratio and a favorable in-situ etch are shown to be the key parameters to achieve 190 µm thick epitaxial layers with excellent morphology.

Polytypism Study in SiC Epilayers Using Electron Backscatter Diffraction

2010 ◽  
Vol 645-648 ◽  
pp. 251-254 ◽  
Author(s):  
Kinga Kościewicz ◽  
Wlodek Strupiński ◽  
Wojciech Wierzchowski ◽  
Krzysztof Wieteska ◽  
Andrzej Roman Olszyna
Keyword(s):  
Growth Temperature ◽  
Vapor Deposition ◽  
Electron Backscatter Diffraction ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Epitaxial Layers ◽  
Cvd Method ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Reactor Pressure

The electron backscatter diffraction (EBSD) detector placed inside a commercial scanning electron microscope (SEM) has been used to study of different SiC polytypes. Different growth conditions in chemical vapor deposition (CVD) method were applied to obtain the 3C- and 4H-SiC polytypes epitaxial layers. Growth processes were conducted on the Si-face on-axis 4H-SiC substrates. The growth temperature was in the range of 1300-1620°C and the reactor pressure was 75mbar. The initial C/Si ratio was varied from 0.075 reaching final value of 1.8. It was observed that intentional ramping of the C/Si ratio at the first stage of the growth clearly influences the 4H/3C factor. The growth temperature and ramping of the C/Si ratio were the main parameters to achieve a homogeneous 3C and 4H-SiC epitaxial layers.

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.

Chloride-Based CVD at High Rates of 4H-SiC on On-Axis Si-Face Substrates

2011 ◽  
Vol 679-680 ◽  
pp. 59-62 ◽  
Author(s):  
Stefano Leone ◽  
Yuan Chih Lin ◽  
Franziska Christine Beyer ◽  
Sven Andersson ◽  
Henrik Pedersen ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Doping Concentration ◽  
Epitaxial Layers ◽  
Power Devices ◽  
High Quality ◽  
Homoepitaxial Growth ◽  
Basal Plane Dislocation ◽  
Background Doping ◽  
Quality Material

The epitaxial growth at 100 µm/h on on-axis 4H-SiC substrates is demonstrated in this study. Chloride-based CVD, which has been shown to be a reliable process to grow SiC epitaxial layers at rates above 100 µm/h on off-cut substrates, was combined with silane in-situ etching. A proper tuning of C/Si and Cl/Si ratios and the combination of different chlorinated precursors resulted in the homoepitaxial growth of 4H-SiC on Si-face substrates at high rates. Methyltrichlorosilane, added with silane, ethylene and hydrogen chloride were employed as precursors to perform epitaxial growths resulting in very low background doping concentration and high quality material, which could be employed for power devices structure on basal-plane-dislocation-free epitaxial layers.

Low Temperature SiGe Heteroepitaxy by Ultrahigh Vacuum Electron Cyclotron Resonance Chemical Vapor Deposition

1995 ◽  
Vol 379 ◽  
Author(s):  
Sung-Jae Joo ◽  
Ki-Hyun Hwang ◽  
Seok-Hee Hwang ◽  
Euijoon Yoon ◽  
Ki-Woong Whang
Keyword(s):  
Growth Rate ◽  
Chemical Vapor Deposition ◽  
Process Parameters ◽  
Vapor Deposition ◽  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Ultrahigh Vacuum ◽  
Chemical Vapor ◽  
Electron Cyclotron ◽  
Epitaxial Layers

ABSTRACTDislocation-free Si1−xGex epilayers are successfully grown on (100) silicon at 440°C by ultrahigh vacuum electron cyclotron resonance chemical vapor deposition (UHV-ECRCVD). The effects of process parameters on the crystallinity of Si1−xGex epitaxial layers were studied. As the GeH4 flow rate increases and consequently Ge fraction increases above 20%, Si1−xGex epilayers become damaged heavily by ions. When Ge fraction is larger than 20%, process parameters like total pressure need to be adjusted to reduce the ion flux for high quality Sil−xGex. Growth rate of Si1−xGex epitaxial layers increases at 440°C with Ge content in the film. It is presumed that the hydrogen desorption from the surface is the rate-limiting step, however, the enhancement in growth rate is comparatively suppressed and delayed.

Low Temperature Silicon Epitaxial Growth by Plasma Enhanced Chemical Vapor Deposition From SiH4/He/H2

1991 ◽  
Vol 235 ◽  
Author(s):  
Yung-Jen Lin ◽  
Ming-Deng Shieh ◽  
Chiapying Lee ◽  
Tri-Rung Yew
Keyword(s):  
Electron Microscopy ◽  
Chemical Vapor Deposition ◽  
Epitaxial Growth ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Ex Situ ◽  
Epitaxial Layers ◽  
Cross Sectional ◽  
Transmission Electron

ABSTRACTSilicon epitaxial growth on silicon wafers were investigated by using plasma enhanced chemical vapor deposition from SiH4/He/H2. The epitaxial layers were growm at temperatures of 350°C or lower. The base pressure of the chamber was greater than 2 × 10−5 Torr. Prior to epitaxial growth, the wafer was in-situ cleaned by H2 baking for 30 min. The epi/substrate interface and epitaxial layers were observed by cross-sectional transmission electron microscopy (XTEM). Finally, the influence of the ex-situ and in-situ cleaning processes on the qualities of the interface and epitaxial layers was discussed in detail.

Basal Plane Dislocation Mitigation in 8º Off-Cut 4H-SiC through In Situ Growth Interrupts during Chemical Vapor Deposition

2009 ◽  
Vol 615-617 ◽  
pp. 61-66 ◽  
Author(s):  
Brenda L. VanMil ◽  
Robert E. Stahlbush ◽  
Rachael L. Myers-Ward ◽  
Yoosuf N. Picard ◽  
S.A. Kitt ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Basal Plane ◽  
Chemical Vapor ◽  
Optimal Growth ◽  
Nucleation Site ◽  
Buffer Layers ◽  
Active Device ◽  
Basal Plane Dislocation ◽  
Conversion Efficiencies

Conversion of basal plane dislocations (BPD) to threading edge dislocations (TED) in 8° off-cut 4H-SiC within an n+ buffer layer would eliminate the nucleation site for Shockley-type stacking faults in active device regions grown on such buffer layers. To that end, the propagation and conversion of BPDs through in situ growth interrupts is monitored using ultraviolet photoluminescence (UVPL) wafer mapping. The optimized growth interrupt scheme lasts for 45 minutes with a propane mass flow of 10 sccm at growth temperature. This scheme has shown a conversion efficiency of up to 99% for samples with electron (hole) concentrations < 5x1014 cm-3 (8x1015 cm-3). Samples subjected to a 45 or 90 minute interrupt under 10 sccm of propane, regardless of conversion efficiency, exhibit a “slit” in the surface morphology associated with each BPD and oriented perpendicular to the off-cut and BPD propagation direction. Repetition of the optimal interrupt sequence with a 5 μm epilayer spacer grown between the two interrupts resulted in the same conversion efficiency as a single optimal growth interrupt. Incorporation of the optimal interrupt into an n+ layer is more complicated as attempts to do so in layers doped with nitrogen to 2x1018, 2x1017 and 2x1016 cm-3 resulted in conversion efficiencies of ~6%.

Sub-Surface Equilibration of Hydrogen with the a-Si:H Network Under Film Growth Conditions

1993 ◽  
Vol 297 ◽  
Author(s):  
ILSIN An ◽  
Y.M. Li ◽  
C.R. Wronski ◽  
R. W. Collins
Keyword(s):  
Hydrogen Diffusion ◽  
Film Growth ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Emission Rates ◽  
Near Surface ◽  
Kinetic Information ◽  
Reaction Processes ◽  
Surface Conversion

In this study we characterize hydrogen diffusion and reaction processes in the near-surface (top 200 Å) of a-Si:H that lead to network equilibration under standard conditions of plasma-enhanced chemical vapor deposition (PECVD). Real time spectroscopic ellipsometry (SE) is used to provide continuous kinetic information on the near-surface conversion of Si-Si to Si-H bonds during exposure of in situ-prepared films at 250°C to filament-generated atomic H. We have found that for optimum PECVD a-Si:H, the formation of additional Si-H bonds is limited by the capture of H at trapping sites, and the rapid diffusion process (D>10-14 cm2/s) by which H reaches the site is not detected optically. Deep trapping occurs at a rate of ∼10 3 s-1 under our filament conditions, estimated to generate ∼1020 cm-3 mobile H in the near-surface of the film. Finally, more than 1021 cm-3 additional H atoms are trapped with emission rates <2×10-7 s-1, suggesting trap depths >2.0 eV. Shallower traps are also detected at lower concentration.

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