Huang Chuanjin, Mu Wenxiang, Zhou Hai, Zhu Yongwei, Xu Xiaoming, Jia Zhitai, Zheng Lei, Tao Xutang
College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics Nanjing 210016 China
College of Mechanical Engineering, Yancheng Institute of Technology Yancheng 224051 China.
RSC Adv. 2018 Feb 8;8(12):6544-6550. doi: 10.1039/c7ra11570a. eCollection 2018 Feb 6.
β-GaO, a semiconductor material, has attracted considerable attention given its potential applications in high-power devices, such as high-performance field-effect transistors. For decades, β-GaO has been processed through chemical mechanical polishing (CMP). Nevertheless, the understanding of the effect of OH on β-GaO processed through CMP with an alkaline slurry remains limited. In this study, β-GaO substrates were successively subjected to mechanical polishing (MP), CMP and etching. Then, to investigate the changes that occurred on the surfaces of the samples, samples were characterised through atomic force microscopy (AFM), three-dimensional laser scanning confocal microscopy (LSCM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). LSCM and SEM results showed that β-GaO is highly vulnerable to brittle fracture during MP. AFM revealed that an ultrasmooth and nondamaged surface with a low of approximately 0.18 nm could be obtained through CMP. XPS results indicated that a metamorphic layer, which mainly contains soluble gallium salt (Ga(OH) ), formed on the β-GaO surface through a chemical reaction. A dendritic pattern appeared on the surface of β-GaO after chemical etching. This phenomenon indicated that the chemical reaction on the β-GaO surface occurred in a nonuniform and selective manner. The results of this study will aid the optimization of slurry preparation and CMP.
β-GaO作为一种半导体材料，因其在高功率器件（如高性能场效应晶体管）中的潜在应用而备受关注。几十年来，β-GaO一直通过化学机械抛光（CMP）进行加工。然而，对于使用碱性浆料通过CMP加工的β-GaO，OH的影响的理解仍然有限。在本研究中，β-GaO衬底依次进行机械抛光（MP）、CMP和蚀刻。然后，为了研究样品表面发生的变化，通过原子力显微镜（AFM）、三维激光扫描共聚焦显微镜（LSCM）、扫描电子显微镜（SEM）和X射线光电子能谱（XPS）对样品进行表征。LSCM和SEM结果表明，β-GaO在MP过程中极易发生脆性断裂。AFM显示，通过CMP可以获得具有约0.18 nm的低粗糙度的超光滑且无损伤的表面。XPS结果表明，通过化学反应在β-GaO表面形成了主要包含可溶性镓盐（Ga(OH) ）的变质层。化学蚀刻后，β-GaO表面出现树枝状图案。这种现象表明β-GaO表面的化学反应以不均匀和选择性的方式发生。本研究结果将有助于优化浆料制备和CMP。
