Crystal Growth of Free Standing 3C-SiC Using Air-Bridge Structure

碳化硅（SiC）是一种很有前途的下一代材料。在SiC多型中，Cubic SiC （3C-SiC）具有高的低场电子迁移率和高的饱和电子漂移速度等先进的电学性能。在硅衬底上异质外延生长的3C-SiC在制造大直径晶圆方面具有显著的成本优势。然而，这种材料的低质量的异质外延生长在硅阻碍了它的发展。由于c -SiC薄膜与Si衬底之间的晶格常数和热膨胀系数不匹配，在SiC/Si界面上发现了大量的缺陷，如错配位错、孪晶、层错和裂纹等。本文报道了在具有气桥结构的Si衬底上进行3C-SiC的异质外延生长，以减少3C-SiC薄膜中的高密度缺陷和应变。有必要研究接近3C-SiC/Si在…More界面的外延生长。采用Si2(CH3)6（六甲基二硅烷：HMDS）在（111）取向硅衬底上主要生长了3C-SiC层。在Si（111）上生长的3C-SiC的结晶度和表面形貌取决于炭化过程。在sic衬底外延生长初期，每个3C-SiC岛的直径取决于CVD生长的温度。采用“微通道外延（MCE）”、“facet-initiated lateral epitaxial overgrowth（FILEO）”、“气桥结构生长（ASG）”和“侧向外延过度生长（LEO）”形成三维细晶。FILEO， ASG和LEO的制备过程在两个CVD生长步骤内。在MCE中形成的ELO结晶度不受成核和生长的控制，呈多晶状。在FILEO中，由于[110]和[111]方向上生长速率的差异，3C-SiC的三角形金字塔是由{110}面形成的。从拉曼光谱上看，与种子区结合硅衬底相比，气隙上方的桥接区结晶度有所提高。在LEO中，ELO区的结晶度不如种子区。在硅衬底上生长3C-SiC的初始阶段，可以通过严格控制实验参数来改善这一结果。少

Silicon carbide(SiC) is a promising material for the next generation. Among SiC polytypes, Cubic SiC (3C-SiC) has advanced electrical properties, like high low-field electron mobility and high saturated electron drift velocity. Heteroepitaxial growth of 3C-SiC on Si substrates allows a significant cost advantage in the fabrication of large-diameter wafers. However, the lower quality of this material grown heteroepitaxially on Si has hindered its development. A large number of defects such as misfit dislocations, twins, stacking faults and cracks have been identified at the SiC/Si interface, owning to the mismatches in both the lattice constant and the thermal expansion coefficients between the 3C-SiC films and Si substrates.This study reports on heteroepitaxial growth of 3C-SiC on Si substrate with air-bridge structure in order to reduce the high density of defects and the strain in the 3C-SiC epilayer. It has been necessary to investigate the epitaxial growth close to the 3C-SiC/Si in … More terface. 3C-SiC layer was grown mainly on a (111)-oriented silicon substrate by using Si2(CH3)6 (Hexamathyldisilane : HMDS). The crystallinity and surface morphology of 3C-SiC grown on Si(111) depended on the carbonization process. The diameter of each 3C-SiC island depended on the temperature of CVD growth at an early stage of epitaxial growth of 3C-SiC on Si substrate.Three-dimensional fine was formed by using "micro-channel epitaxy(MCE)", "facet-initiated lateral epitaxial overgrowth(FILEO)", "air-bridged structural growth(ASG)" and "lateral epitaxial overgrowth(LEO)". FILEO, ASG and LEO have the fabrication procedure within two CVD growth steps. The crystallinity of ELO formed in MCE became like polycrystalline without the control of nucleation and growth. In FILEO, triangular pyramid of 3C-SiC was formed by {110} facet, owning to the difference of growth rate along between [110] and [111] direction. The crystallinity of bridged regions above air-gap was improved from Raman spectra, compared with seed regions combined Si substrate in ASG. The crystallinity of ELO regions was inferior to that of seed regions in LEO. This result may be improved by close control of experimental parameters at initial stage of 3C-SiC grown on Si substrates. Less