Reduction of morphological defects in 4H-SiC epitaxial layers

Li, Yun; Zhao, Zhiying; Yu, Le; Wang, Yi; Zhou, Ping; Niu, Yingxi; Li, Zhonghui; Chen, Yunfeng; Han, Ping

doi:10.1016/j.jcrysgro.2018.10.023

Cited by 16 publications

(6 citation statements)

References 17 publications

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“…At the same time, as the proportion of Si in the gas gradually increases, it is easy to form silicon droplets or silicon clusters attached to the surface of the substrate, which increases the RMS. In addition, in the surface etching process of 4H-SiC, since the etching effect of H 2 on C atoms is greater than that of Si atoms [13,19], when the Si/H ratio increases, the binding ability of H 2 and Si atoms is relatively weak, resulting in insufficient etching effect. On the other hand, the growth rate tends to be saturated at a high Si/H ratio, which is more likely to lead to rougher surface morphology and surface inhomogeneity [39].…”

Section: Si/h Ratiomentioning

confidence: 99%

“…As the pressure decreases, the step bunching on the epitaxial surface becomes more and more obvious, and the triangular defect density, which is fatal to the device, is reduced. This is believed to be due to the increased surface mobility and diffusion length of adatoms and the decreased epitaxial surface free energy [13,[19][20][21]. When the surface free energy is relatively high, the epitaxial surface tends to minimize the surface free energy by forming defects or steps.…”

Section: Introductionmentioning

confidence: 99%

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Surface Uniformity of Wafer-Scale 4H-SiC Epitaxial Layers Grown under Various Epitaxial Conditions

et al. 2022

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Wide band gap semiconductor 4H-SiC is currently widely used in the manufacture of high-frequency and high-voltage power devices. The size of commercial 4H-SiC wafers is increasing, from 4 inches to 6 inches. Surface roughness, as one of the parameters reflecting the quality of epitaxial wafers, is closely related to the performance of power devices. Most studies on the uniformity of epitaxial layers did not focus on RMS; however, the uniformity of epitaxial surface roughness also affects the device yield. In this paper, the root mean square roughness (RMS) and uniformity (σ) of epitaxial wafers are investigated as a function of epitaxy conditions, including C/Si ratio, growth temperature, and Si/H ratio. It was found that the best values of RMS and σ were obtained with C/Si ratio = 1 in the experimental range. Growth temperature had opposite effects on RMS and σ, with better RMS uniformity obtained at lower growth temperatures. An insignificant effect on RMS and σ has been found with the Si/H ratio changes in the experimental range. We hope that our experiments can play a certain role in promoting the improvement of the surface roughness of wafer-scale 4H-SiC epitaxial layers.

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Section: Si/h Ratiomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surface Uniformity of Wafer-Scale 4H-SiC Epitaxial Layers Grown under Various Epitaxial Conditions

et al. 2022

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“…TDs without a core are generally considered to be caused by differences in growth conditions between the substrate, buffer layer, and epitaxial layer, while TDs with a core are considered to be caused by falling objects or defects of the substrate and nucleation of dislocation (TSD, BPD, MP) [25,26]. In addition, some studies show that collapse in the growth process can lead to the formation of TDs, and some people think that TDs nucleate because of silicon drops falling on the surface [27].…”

Section: Introductionmentioning

confidence: 99%

Multiple-Layer Triangular Defects in 4H-SiC Homoepitaxial Films Grown by Chemical Vapor Deposition

et al. 2023

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In this study, a special triangular defect (TD) was identified on 4H-SiC epitaxial wafers. The morphology and composition characteristics of these special TDs were revealed by Raman, atomic force microscope (AFM), and scanning electron microscope (SEM). Compared to ordinary triangular defects, this defect protruded from the epitaxial layer and exhibited a laminated shape. The study also discussed the effects of several factors, such as C/Si ratio and growth time, on the triangular defects. Through analysis of these results, we developed methods to suppress the triangular defects. This research provides new insights into the morphology, structure, and composition of this serious destructive defect and is helpful for improving the performance of SiC epitaxial wafers.

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“…Among the morphological defects, micropipes have serious impact on the device performance but are preventable, since the substrates with micropipe density less than 0.1 cm −2 are commercially available [16][17][18]. In our previous paper, we reported the density of other morphological defects in a 4-inch 4H-SiC epitaxial wafer, as well as their probability of causing Schottky diode power device failure [19]. The average morphological defect (including TDs, downfalls, particles, carrots) density in the 4-inch 4H-SiC epitaxial layers is 1.25 cm −2 , in which the TDs, the downfalls, the particles, and the carrots account for approximately 60%, 2%, 31% and 7%, Micromachines 2020, 11, 609 2 of 13 respectively.…”

Section: Introductionmentioning

confidence: 99%

Effect of Various Defects on 4H-SiC Schottky Diode Performance and Its Relation to Epitaxial Growth Conditions

Meng

et al. 2020

Micromachines

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In this paper, the chemical vapor deposition (CVD) processing for 4H-SiC epilayer is investigated with particular emphasis on the defects and the noise properties. It is experimentally found that the process parameters of C/Si ratio strongly affect the surface roughness of epilayers and the density of triangular defects (TDs), while no direct correlation between the C/Si ratio and the deep level defect Z1/2 could be confirmed. By adjusting the C/Si ratio, a decrease of several orders of magnitudes in the noise level for the 4H-SiC Schottky barrier diodes (SBDs) could be achieved attributing to the improved epilayer quality with low TD density and low surface roughness. The work should provide a helpful clue for further improving the device performance of both the 4H-SiC SBDs and the Schottky barrier ultraviolet photodetectors fabricated on commercial 4H-SiC wafers.

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Reduction of morphological defects in 4H-SiC epitaxial layers

Cited by 16 publications

References 17 publications

Surface Uniformity of Wafer-Scale 4H-SiC Epitaxial Layers Grown under Various Epitaxial Conditions

Surface Uniformity of Wafer-Scale 4H-SiC Epitaxial Layers Grown under Various Epitaxial Conditions

Multiple-Layer Triangular Defects in 4H-SiC Homoepitaxial Films Grown by Chemical Vapor Deposition

Effect of Various Defects on 4H-SiC Schottky Diode Performance and Its Relation to Epitaxial Growth Conditions

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