Direct Wafer Bonding of SiC-SiC by SAB for Monolithic Integration of SiC MEMS and Electronics

Mu, Fengwen; Iguchi, Kenichi; Nakazawa, Hiroyuki; Takahashi, Yoshikazu; Fujino, Masataka; Suga, Tadatomo

doi:10.1149/2.0011609jss

Cited by 21 publications

(17 citation statements)

References 40 publications

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“…where E = 530 GPa, is the modulus of elasticity for single crystalline SiC, t is the thickness of the wafer, and L is the crack length. With a 300 • C annealing temperature, the bonded SiC substrate and n − SiC epitaxy layer demonstrated a bonding strength of 1473 mJ/m 2 , which is comparable with the reported result of SiC-SiC substrate direct bonding [16]. Although this result is much less than the fracture energy between the Si and C-terminated ideal surfaces (considered as bulk SiC strength of 3400 J/m 2 [23]), it is higher to sustain post-bonding processes such as mechanical grinding and polishing in micro-fabrication process (>1000 mJ/m 2 ) [24].…”

Section: Bonding Uniformity and Bonding Strengthsupporting

confidence: 85%

“…SiC-SiC strong bonding at room temperature by modified surface activation bonding (SAB) with Fe-Si deposited layer or Si deposited layer have been demonstrated or proved to be feasible [2,3]. Although direct wafer bonding technique of SiC-SiC without any non-SiC interfacial have been reported [16,17], the SiC substrate bonding with the SiC epitaxy growth layer is still a major concern for the fabrication of ultrahigh-voltage devices. In this paper, the prospects of a low temperature hydrophilic wafer level direct bonding between SiC substrate and n − SiC epitaxy layer with O 2 plasma activation are investigated.…”

Section: Introductionmentioning

confidence: 99%

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Low Temperature Hydrophilic SiC Wafer Level Direct Bonding for Ultrahigh-Voltage Device Applications

Zhang

et al. 2021

Micromachines

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SiC direct bonding using O2 plasma activation is investigated in this work. SiC substrate and n− SiC epitaxy growth layer are activated with an optimized duration of 60s and power of the oxygen ion beam source at 20 W. After O2 plasma activation, both the SiC substrate and n− SiC epitaxy growth layer present a sufficient hydrophilic surface for bonding. The two 4-inch wafers are prebonded at room temperature followed by an annealing process in an atmospheric N2 ambient for 3 h at 300 °C. The scanning results obtained by C-mode scanning acoustic microscopy (C-SAM) shows a high bonding uniformity. The bonding strength of 1473 mJ/m2 is achieved. The bonding mechanisms are investigated through interface analysis by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). Oxygen is found between the two interfaces, which indicates Si–O and C–O are formed at the bonding interface. However, a C-rich area is also detected at the bonding interface, which reveals the formation of C-C bonds in the activated SiC surface layer. These results show the potential of low cost and efficient surface activation method for SiC direct bonding for ultrahigh-voltage devices applications.

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Section: Bonding Uniformity and Bonding Strengthsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Low Temperature Hydrophilic SiC Wafer Level Direct Bonding for Ultrahigh-Voltage Device Applications

Zhang

et al. 2021

Micromachines

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“…where D s is the surface diffusivity (m 2 s À1 ), C is the ion concentration (9.64 9 10 22 ions cm À3 for SiC), c is the surface free energy (1.40 J m À2 ), 32 and k B T is the thermal energy (2.93 9 10 À2 eV at 67°C for our work). D s has the expression of:…”

Section: Surface Morphologymentioning

confidence: 99%

Ion irradiation effect on spark plasma sintered silicon carbide ceramics with nanostructured ferritic alloy aid

Ning

2018

J Am Ceram Soc

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Silicon carbide (SiC) is a promising material with excellent chemical and physical performance under irradiation for advanced nuclear applications. The addition of nanostructured ferritic alloy (NFA) has been proven beneficial for the densification of SiC ceramics based on our previous work. To understand their microstructural evolution and irradiation resistance, spark plasma sintered (SPSed) SiC ceramics with and without NFA aid (0 vol% NFA-100 vol% SiC, 2.5 vol% NFA-97.5 vol% SiC, and 5 vol% NFA-95 vol% SiC) were exposed to 5 MeV Si ++ irradiation. The ion irradiation strongly modifies the surface morphology with isolated sand dune shaped structures, which can be explained by the Bradley-Harper (B-H) theory. SRIM simulation for both the pure SiC and NFA-SiC predicts similar surface damage of~45 dpa and peak damage of~790 dpa at~2.0 lm depth. For the actual samples, the SiC matrix is completely amorphous up to~2.2 lm thickness (from the surface dune valley to the amorphous layer boundary), which is consistent with the SRIM predicted depth of~2.3 lm. Reaction product (Fe, Cr) 3 Si in the NFA-SiC samples maintains a crystalline structure with dislocation loops. A defect rate model is applied to understand the fundamental difference in ion irradiation resistance between SiC and (Fe,Cr) 3 Si. K E Y W O R D S defects, microstructure, nanostructured ferritic alloy aid, Si ++ ion irradiation, silicon carbideHow to cite this article: Ning K, Lu K. Ion irradiation effect on spark plasma sintered silicon carbide ceramics with nanostructured ferritic alloy aid.

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“…At the interface, a bright seamless intermediate layer of about 8 nm should be amorphous because it has no lattice fringes and is distinct from adjacent crystalline phase. From data by previous studies, amorphous layer formation was caused by Ar-FAB bombardment [ 29 , 30 ]. Accordingly, EDX liner mapping of Si, C and O elements distribution of a small sample is shown in Figure 5 b, the analysis location and range are roughly shown as the yellow dotted line in Figure 5 a.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of SiC Sealing Cavity Structure for All-SiC Piezoresistive Pressure Sensor Applications

et al. 2020

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High hardness and corrosion resistance of SiC (silicon carbide) bulk materials have always been a difficult problem in the processing of an all-SiC piezoresistive pressure sensor. In this work, we demonstrated a SiC sealing cavity structure utilizing SiC shallow plasma-etched process (≤20 μm) and SiC–SiC room temperature bonding technology. The SiC bonding interface was closely connected, and its average tensile strength could reach 6.71 MPa. In addition, through a rapid thermal annealing (RTA) experiment of 1 min and 10 mins in N2 atmosphere of 1000 °C, it was found that Si, C and O elements at the bonding interface were diffused, while the width of the intermediate interface layer was narrowed, and the tensile strength could remain stable. This SiC sealing cavity structure has important application value in the realization of an all-SiC piezoresistive pressure sensor.

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Direct Wafer Bonding of SiC-SiC by SAB for Monolithic Integration of SiC MEMS and Electronics

Cited by 21 publications

References 40 publications

Low Temperature Hydrophilic SiC Wafer Level Direct Bonding for Ultrahigh-Voltage Device Applications

Low Temperature Hydrophilic SiC Wafer Level Direct Bonding for Ultrahigh-Voltage Device Applications

Ion irradiation effect on spark plasma sintered silicon carbide ceramics with nanostructured ferritic alloy aid

Fabrication of SiC Sealing Cavity Structure for All-SiC Piezoresistive Pressure Sensor Applications

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