Highly efficient finishing of large-sized single crystal diamond substrates by combining nanosecond pulsed laser trimming and plasma-assisted polishing
Highly efficient finishing of large-sized single crystal diamond substrates by combining nanosecond pulsed laser trimming and plasma-assisted polishing
复制标题
DOI：
10.1016/j.ceramint.2023.03.038
复制
发表时间：
2023-03
影响因子：
5.2
通讯作者：
Nian Liu;Kenta Sugimoto;Naoya Yoshitaka;Hideaki Yamada;Rongyan Sun;Kenta Arima;K. Yamamura
中科院分区：
文献类型：
--
作者：
Nian Liu;Kenta Sugimoto;Naoya Yoshitaka;Hideaki Yamada;Rongyan Sun;Kenta Arima;K. Yamamura
金刚石是制作功率器件、散热器、声表面波等功能元件的理想材料。然而，金刚石的极端硬度和脆性性质使得难以研磨和抛光以满足此类应用的粗糙度要求。在这项研究中，一种新的混合工艺相结合的纳秒脉冲激光修整包括一系列的选择性激光平面烧蚀（LPA）和等离子体辅助抛光（PAP）提出了平坦化和光滑的大尺寸单晶金刚石（SCD）基板。当在未涂覆的SCD基底上进行LPA时，产生深爆炸洞穴和裂纹。同时，当用相同的条件通过LPA处理Au涂覆的SCD衬底时，材料被均匀地去除几微米，其中在SCD表面上产生自维持石墨层，并且材料作为石墨“活塞”穿透到SCD衬底中而被去除。在所提出的混合工艺的验证中，通过激光修整79和538 s使10和20 mm正方形Au涂覆的SCD衬底变平，使整个SCD表面的p-v值分别降低了1.70和1.150 μm。随后，激光修整处理的SCD基板通过PAP平滑化6.5和34小时，对于10和20-mm正方形尺寸的SCD基板，分别获得0.2和1 μm或更小的平坦度和0.51和0.53 nm的表面粗糙度。通过分光光度计和拉曼光谱分析，在激光修整过程中，SCD体相中没有非金刚石相生成，混合工艺后检测到金刚石表面。
Diamond is an ideal material for fabricating functional components applied in power devices, heat spreaders, and surface acoustic wave. However, diamond's extreme hardness and brittleness nature makes it difficult to grind and polish to meet the roughness requirement for such applications. In this study, a novel hybrid process combining nanosecond pulsed laser trimming comprising a series of selective laser plane ablation (LPA) and plasma-assisted polishing (PAP) was proposed to flatten and smooth large-sized single-crystal diamond (SCD) substrate. When LPA was performed on an uncoated SCD substrate, deep explosion caverns and cracks were generated. Meanwhile, the material was uniformly removed by a few microns when an Au-coated SCD substrate was processed by LPA with the same conditions, in which a self-maintaining graphite layer on SCD surface was generated, and material was removed as a graphite “piston” penetrated into SCD substrate. In the validation of the proposed hybrid process, 10 and 20-mm square Au-coated SCD substrates were flattened by laser trimming for 79 and 538 s, reducing the p–v value of the entire SCD surface by ∼70 and ∼150 μm, respectively. Subsequently, the laser-trimming-processed SCD substrates were smoothed by PAP for 6.5 and 34 h, obtaining flatness of 0.2 and 1 μm or less, and surface roughness of 0.51 and 0.53 nm for SCD substrates of 10 and 20-mm square sizes, respectively. Proven by spectrophotometer and Raman results, no non-diamond phase was generated in the bulk of SCD during laser trimming and diamond surface was detected after hybrid process.