The surface microstructure of SiC epitaxial films, grown by atom replacement

Such properties of silicon carbide (SiC) as high hardness, chemical resistance, high thermal conductivity, wide band gap (2.2 – 3.7 eV) and high breakdown voltage [1] cause a great interest of that material in fabrication of... [ view full abstract ]

Such properties of silicon carbide (SiC) as high hardness, chemical resistance, high thermal conductivity, wide band gap (2.2 – 3.7 eV) and high breakdown voltage [1] cause a great interest of that material in fabrication of semiconductor devices for various purposes.
There are some difficulties for heteroepitaxial growth of β-SiC layers on silicon (Si) substrate. Primarily this growth suppressed by large lattice mismatches (~ 19%) [2] and thermal expansion coefficient mismatches (8%) between SiC and Si lattices. In [2] authors have been offered a new approach for SiC film formation onto Si substrate. The main idea of their work based on process of replacement some atoms of Si substrate by energetic C atoms, which leads to SiC layer forming.
In this article, SiC films, obtained by influence of CO and SiH4 (264 Pa, 1250°C, 15 min) gases mixture on high-resistance single crystalline (111) oriented n-type Si substrate, were measured by X-ray diffraction (XRD), profilometry, atomic force microscopy (AFM), X-ray reflectometry (XRR) and Raman microscopy to study the phase composition, surface microstructure and surface roughness.
It was revealed that SiC films contain both nanocrystalline and single crystalline 3C-SiC structures with highly perfection β-SiC crystallites. The surface of the film has a pyramidal or step-like structure with a distinct fragmentation of the faces and the height variations of up to 36 nm.
It was found that the treatment of silicon substrates by acid mixture of HF: HNO3 (in 1:10 proportion) polishes their surface and leads to the appearance of the intensive oscillations of X-ray reflections, which allows to determine the thickness of the SiC film (about 100 nm). On the other hand, the chemical treatment causes emerging of etching pits and increases average roughness of surface, which results in decreasing of intensity of the main X-ray peak.

[1] Wu W, Chen DH, Cheung WY, Xu JB, Wong SP, Kwok RWM, Wilson IH 1998 Appl. Phys. A 66 S539–S543
[2] Kukushkin SA and Osipov AV 2014 J. of Phys. D: Appl. Phys. 47 313001-41