Numerical analysis of the Gibbs–Thomson effect on trench-filling epitaxial growth of 4H-SiC

Mochizuki, Kazuhiro; Ji, Shiyang; Kosugi, Ryoji; Kojima, Kazutoshi; Yonezawa, Yoshiyuki; Okumura, Hajime

doi:10.7567/apex.9.035601

Cited by 14 publications

(19 citation statements)

References 26 publications

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“…There have also been significant advances in understanding the mechanisms of epitaxial growth of trench filling. [23][24][25] In addition, Ryoji et al [26] have established a key manufacturing process of superjunction structure with thickness over 20 µm and high aspect ratio, and the theoretical limit of 6.5-kV class 4H-SiC superjunction MOSFET is broken through by the trench filling epitaxial growth method. Consequently, it is feasible to study the trench-filled epitaxial growth method of SiC super-junction devices with high breakdown voltage.…”

Section: Introductionmentioning

confidence: 99%

A 4H-SiC trench MOSFET structure with wrap N-type pillar for low oxide field and enhanced switching performance

2022

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In this article, an optimized silicon carbide (SiC) trench Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) structure with side-wall p-type pillar (p-pillar) and wrap n-type pillar (n-pillar) in the n-drain was investigated utilizing Silvaco TCAD simulations. The optimized structure main includes a p+ buried region, a light n-type current spreading layer (CSL), a p-type pillar region, and a wrapping n-type pillar region at the right and bottom of the p-pillar. The improved structure is named SNPPT-MOS. The side-wall p-pillar region could better relieve the high electric field around the p+ shielding region and the gate oxide in the off-state mode. The wrapping n-pillar region and CSL can also effectively reduce the specific on-resistance (R on,sp). As a result, the SNPPT-MOS structure exhibits that a higher figure of merit (FoM) related to the breakdown voltage (V BR) and the R on,sp (V BR 2/R on,sp) of the SNPPT-MOS is improved by 44.5%, respectively, with comparison to that of the conventional trench gate SJ MOSFET (full-SJ-MOS). In addition, the SNPPT-MOS structure achieves a much faster-switching speed than the full-SJ-MOS, and the result indicated an appreciable reduction in the switching energy loss.

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Section: Introductionmentioning

confidence: 99%

A 4H-SiC trench MOSFET structure with wrap N-type pillar for low oxide field and enhanced switching performance

2022

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“…A multiscale analysis that combines a whole CVD reactor analysis (i.e., macroscale analysis) using computational fluid dynamics (CFD) and trench-profile analysis (i.e., microscale analysis) has been reported in the cases of low-temperature and low-pressure CVD of 3C-SiC 10,11) and high-temperature and subatmospheric-pressure CVD of 4H-SiC. [12][13][14][15][16] Here 4H-SiC is preferred for power devices because its dielectric-breakdown field is about twice as large as that of 3C-SiC. 17) Trench-filling of 4H-SiC at absolute temperature T exceeding 1913 K 12) has been well-described by an improved continuum-diffusion model, [13][14][15][16] in which the Gibbs−Thomson (GT) effect, 18) i.e., the effect of radius of curvature (r) of a growing surface on the equilibrium gasphase concentration of growing species i (C i g e ), is incorporated into a conventional continuum-diffusion model.…”

Section: Introductionmentioning

confidence: 99%

Gibbs–Thomson effect on aluminum doping during trench-filling epitaxial growth of 4H-SiC

Mochizuki

Adachi

et al. 2019

Jpn. J. Appl. Phys.

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Diffusion equations were solved to examine how the aluminum concentration in 4H-SiC grown on a trenched substrate is influenced by the Gibbs −Thomson (GT) effect. The GT effect increases or decreases the equilibrium gas-phase concentration of growing species in the vicinity of the top or bottom of the trench, respectively, which results in a part of the incident growing species, excluding the central area of the trench, diffusing inward. After fitting activity coefficient of a conditional constituent AlC in solid solution AlSiC and surface free energy of 4H-SiC, we determined the aluminum fluxes toward the top and bottom in such a way that the flux ratio of aluminum to silicon equals the AlC mole fraction at the top (X s t ) and bottom (X s b ), respectively. Calculated X s b was lower than X s t and almost agreed with the measured X s b in filled trenches, showing the GT effect on AlC being weaker than that on SiC.

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“…Although the theoretical limit of 6.5 kV-class 4H-SiC SJ metal-oxide-semiconductor field-effect transistors (MOSFETs) has been broken by trench-filling epitaxial growth, 12) complete filling of SiC around the trench edge is yet to be attained. 18) In contrast, a multi-epitaxial growth method, in which epitaxial growth and ion implantation are repeated alternately until a certain drift layer thickness is achieved, has been successfully employed; for example, 1.54 kV SJ p-n diodes 22) and 0.82 kV SJ V-groove trench MOSFETs 21) fabricated using 9 MeV Al-ion implantation, as well as 1.17 kV SJ Vgroove trench MOSFETs 16) and 1.2 kV-class SJ trench MOSFETs 17) fabricated using sub-MeV Al-ion implantation. The use of sub-MeV ion implantation minimizes lateral straggling of implanted ions; however, this was in exchange for six times 16) or seven times 17) repetition of epitaxial growth/sub-MeV-ion implantation steps.…”

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Re-evaluation of energy dependence of electronic stopping cross-section for Al ions into 4H-SiC (0001)

Mochizuki

Nishimura

Mishima

2022

Jpn. J. Appl. Phys.

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To apply channeled-ion implantation to cost-effective multi-epitaxial growth for 4H-SiC superjunction devices, we re-evaluated the Al-ion energy (E) dependence of the electronic stopping cross section (Se) in 4H-SiC based on the recently reported secondary-ion mass spectrometry measured depth profiles. By including the effect of stripping of the ion electrons on the E dependence of Se, we successfully reproduced the reported maximum channeled ranges of Al into 4H-SiC (0001), ranging from 0.6 μm at the implantation-energy (E0) of 60 keV to 7.2 μm at E0 of 8 MeV.

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Numerical analysis of the Gibbs–Thomson effect on trench-filling epitaxial growth of 4H-SiC

Cited by 14 publications

References 26 publications

A 4H-SiC trench MOSFET structure with wrap N-type pillar for low oxide field and enhanced switching performance

A 4H-SiC trench MOSFET structure with wrap N-type pillar for low oxide field and enhanced switching performance

Gibbs–Thomson effect on aluminum doping during trench-filling epitaxial growth of 4H-SiC

Re-evaluation of energy dependence of electronic stopping cross-section for Al ions into 4H-SiC (0001)

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