氧化铍基HFCVD金刚石薄膜及其热性能的研究

【作者】 方梅；

【导师】 余志明；

【作者基本信息】 中南大学 ， 材料学， 2008， 硕士

【摘要】 随着电子和光子产品朝着速度更快、体积更小、功率更高的方向发展,基片材料的选择和提高基片材料的导热性能成为重要的研究课题。多晶氧化铍陶瓷因其具有高的低温热导率和低的介电常数,是高热导陶瓷家族中用于电子器件的优选材料。本文通过热丝化学气相沉积的方法在多晶氧化铍陶瓷上沉积金刚石薄膜以提高其复合体的热性能,促使氧化铍适应电子器件微型化、高集成方向的发展。通过金相显微镜、扫描电镜、原子力显微镜的观察,X射线衍射仪的分析和激光热物性测试仪的测量,研究了氧化铍基体上沉积金刚石薄膜的过程中,控制参数对金刚石薄膜质量和性能的影响,得出结论如下:1、沉积前用水磨砂纸和氢氟酸预处理基体,能显著提高膜与基体之间的结合,促进形成致密连续的金刚石薄膜。氢氟酸处理10min最有利于金刚石在氧化铍上的形核和长大,得到质量高的金刚石薄膜。2、沉积过程中通过控制沉积参数能够得到各种结构的金刚石薄膜:随着CH₄浓度的升高,或者反应气体总流量的增加,金刚石的晶粒尺寸减小,结晶性能降低。沉积压强为10torr,气体总流量为50sccm,CH₄浓度为3%时,沉积得到的薄膜金刚石晶粒尺寸细小均匀,且表面粗糙度低。3、不同膜与基体的串并联方式对复合体的热导率影响很大:正面和侧面镀金刚石薄膜能显著提高复合体的热导率,底面的金刚石薄膜对复合体热导的影响不大。另外,金刚石的质量对复合体的热导率也有较大影响:取向程度强、晶粒尺寸大的金刚石薄膜可使对应的复合体热导率的提高大。更多还原

【Abstract】 The thermal conductivity of substrates applied in electronic industry become interested by researchers because the devices become smaller、faster and higher power. Beryllia （BeO） ceramics are optimum materials for applications on electronic device because of high thermal conductivity （TC） at room temperature and low dielectric constant. However, the TC of BeO is still a limit for electronic device developing to minitype and high-density. In the present work, diamond films were deposited on beryllia substrates by Hot Filament Chemical Vapor Deposition （HFCVD） to improve the thermal behavior of BeO. The surface morphologies of diamond films were characterized by metallographic microscopes scanning electron microscope （SEM） and atom force microscope（AFM）, and the components and textures were analyzed by X-ray diffractometer（XRD）, while the thermal conductivity were calculated according to the thermal diffusivity measured by laser-diathermometer. Influences of depositional conditions on the quality of diamond films and the properties of composites were analyzed according to the experiments.The following conclusions can be drawn from this work:1、The cohesion of films and substrates can be improved by scratching BeO with waterproof abrasive paper, and HF pre-treatment can be effective to prevent the films scaling off from BeO, thus uniform diamond films can be obtained.2、The grain size and the crystallinity of diamond reduced with the increasing of the concentration of CH₄, or the total flow rate of CH₄ and H₂. Uniform and lower roughness films can be obtained when ratio of CH₄ and H₂ was 48.5 sccm to 1.5 sccm.3、Diamond grown on frontal surface and side face of BeO can enhance the thermal conductivity of diamond/BeO composites by 15% and 11% respectively, while the contribution of diamond on back surface is not so remarkable. Besides, textured diamond with larger grain size can enhance the thermal conductivity of the composite by 35% compared with original BeO.更多还原