Room light anodic etching of highly doped n-type 4 H-SiC in high-concentration HF electrolytes: Difference between C and Si crystalline faces

Gautier, Gaël; Cayrel, Frédéric; Capelle, Marie; Billoue, Jérôme; Song, Xiaoshi; Michaud, Jean-François

doi:10.1186/1556-276x-7-367

Cited by 26 publications

(28 citation statements)

References 18 publications

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“…The SiC etching mechanism proposed by Shor and Kurtz 16 has been generally accepted. 13,[17][18][19][20][21][22][23] According to their hypothesis, anodic etching of SiC in aqueous HF occurs in two steps: oxidation of SiC and dissolution of the formed oxide. They suggested that oxidation of SiC occurs via the following reactions: 16 SiC…”

Section: Methodsmentioning

confidence: 99%

Influence of the anodic etching current density on the morphology of the porous SiC layer

Cao¹,

Luong

Dao

2014

AIP Advances

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In this report, we fabricated a porous layer in amorphous SiC thin films by using constant-current anodic etching in an electrolyte of aqueous diluted hydrofluoric acid. The morphology of the porous amorphous SiC layer changed as the anodic current density changed: At low current density, the porous layer had a low pore density and consisted of small pores that branched downward. At moderate current density, the pore size and depth increased, and the pores grew perpendicular to the surface, creating a columnar pore structure. At high current density, the porous structure remained perpendicular, the pore size increased, and the pore depth decreased. We explained the changes in pore size and depth at high current density by the growth of a silicon oxide layer during etching at the tips of the pores.

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Section: Methodsmentioning

confidence: 99%

Influence of the anodic etching current density on the morphology of the porous SiC layer

Cao¹,

Luong

Dao

2014

AIP Advances

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“…This setup was described in previous work. 11 In this case, the back side contact is ensured by the electrolyte. In the case of high doping levels, the anodization can be conducted without any additional lighting.…”

Section: Methodsmentioning

confidence: 99%

“…However, a pore enlargement occurs when the applied current density increases. 11 At first, porous samples were prepared according to the following cleaning procedure. The substrates were sequentially cleaned in a H 2 SO 4 (96%) : H 2 O 2 (1:1) solution at 120 • C during 5 min.…”

Section: Methodsmentioning

confidence: 99%

“…If the semiconductor crystal shows polar properties, for instance in the case of hexagonal SiC or GaN, we must take into account the crystalline face where the anodization is performed. 11 In this study, SiC wafer properties are fixed and various anodization conditions were applied to quantify the effect of additives in the electrolyte, anodization regime and HF concentration.…”

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confidence: 99%

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Systematic Study of Anodic Etching of Highly Doped N-type 4H-SiC in Various HF Based Electrolytes

Gautier

Biscarrat

Valente

et al. 2013

J. Electrochem. Soc.

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In this paper, we study the electrochemical anodization of n-type heavily doped 4H-SiC wafers in HF based electrolytes without any UV light assistance. We present, in particular, the differences observed when varying the process conditions such as the HF concentration, the type of additive and the applied current regime. The use of a solvent such as acetic acid seems to be more suitable to produce homogeneous morphologies compared with Cetyltrimethylammonium chloride (CTAC), Ammonium dodecylsulfate (ADS), Triton X-100 surfactants. In addition, the use of pulsed current regimes improves the global homogeneity of the porous layers. Nevertheless, for some unexplained reasons, at specific concentrations of 15 and 50%, this homogeneity cannot be ensured and the observed morphology mixes mesopores and macropores with random orientations.

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“…The substrate removal was obtained by electrochemical etching. ECE is an oxidation/oxide-removal process obtained by dipping the SiC wafer in a hydrofluoridric acid-based solution and electrically supply holes for the oxidation through a 100 nm aluminium back metal contact [6,[21][22][23]. The process is capable of removing highly doped (≥ 10 18 cm −3 ) p-type and n-type layers but is selective towards low-doped n-type layers (selectivity > 1000:1 with respect to the 5 × 10 13 cm −3 doped n − layer).…”

Section: Sample Preparationmentioning

confidence: 99%

Investigation of the Young’s Modulus and the Residual Stress of 4H-SiC Circular Membranes on 4H-SiC Substrates

et al. 2019

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The stress state is a crucial parameter for the design of innovative microelectromechanical systems based on silicon carbide (SiC) material. Hence, mechanical properties of such structures highly depend on the fabrication process. Despite significant progresses in thin-film growth and fabrication process, monitoring the strain of the suspended SiC thin-films is still challenging. However, 3C-SiC membranes on silicon (Si) substrates have been demonstrated, but due to the low quality of the SiC/Si heteroepitaxy, high levels of residual strains were always observed. In order to achieve promising self-standing films with low residual stress, an alternative micromachining technique based on electrochemical etching of high quality homoepitaxy 4H-SiC layers was evaluated. This work is dedicated to the determination of their mechanical properties and more specifically, to the characterization of a 4H-SiC freestanding film with a circular shape. An inverse problem method was implemented, where experimental results obtained from bulge test are fitted with theoretical static load-deflection curves of the stressed membrane. To assess data validity, the dynamic behavior of the membrane was also investigated: Experimentally, by means of laser Doppler vibrometry (LDV) and theoretically, by means of finite element computations. The two methods provided very similar results since one obtained a Young’s modulus of 410 GPa and a residual stress value of 41 MPa from bulge test against 400 GPa and 30 MPa for the LDV analysis. The determined Young’s modulus is in good agreement with literature values. Moreover, residual stress values demonstrate that the fabrication of low-stressed SiC films is achievable thanks to the micromachining process developed.

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Room light anodic etching of highly doped n-type 4 H-SiC in high-concentration HF electrolytes: Difference between C and Si crystalline faces

Cited by 26 publications

References 18 publications

Influence of the anodic etching current density on the morphology of the porous SiC layer

Influence of the anodic etching current density on the morphology of the porous SiC layer

Systematic Study of Anodic Etching of Highly Doped N-type 4H-SiC in Various HF Based Electrolytes

Investigation of the Young’s Modulus and the Residual Stress of 4H-SiC Circular Membranes on 4H-SiC Substrates

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