【作者】 王静；

【导师】 邓新绿； 刘贵昌；

【作者基本信息】 大连理工大学 ， 化学工艺， 2009， 博士

【摘要】 随着电子技术、自动化技术、信息产业、数字网络产业飞速发展,铜在微电子,微电子机械系统（MEMS）,精密仪器散热装置等高新技术上的重要作用日益突显。铜在应用过程中存在强度低,易氧化,易磨损,耐腐性差等缺点,限制了铜的应用。本文针对铜在应用中的缺点,采用不同的等离子体制备技术,在铜基体上制备了Ti/Ti_xC_y/DLC功能梯度材料,实现了改善铜基体与DLC膜结合力的目的,并强化了铜的性能。对梯度过渡层的结构进行设计,将等离子体增强非平衡磁控溅射物理气相沉积（PEUMS-PVD）和电子回旋共振微波等离子体增强化学气相沉积（MW-ECRPECVD）技术相结合,分别采用Ti、Si作为过渡层元素制备梯度过渡层,来改善类金刚石（DLC）膜与铜基体之间的结合力。所制备的膜具有典型的类金刚石结构,厚度达到纳米量级,并且表面粗糙度低。DLC膜的硬度和弹性模量都远远的超过基体。以Si为过渡层元素沉积Si/Si_xN_y/DLC膜时,Si靶会发生靶中毒现象而使溅射率降低。而Ti可以作为过渡层元素在铜基体上沉积DLC膜,但是过渡层中含有氢元素,残余应力较高,降低了膜与基体的结合力和表面硬度。采用等离子增强非平衡磁控溅射技术沉积Ti/Ti_xC_y梯度过渡层,避免了在过渡层中引入氢元素,减小了薄膜的应力集中,增加了过渡层的稳定性。XRD、XPS分析表明,过渡层中形成TiC纳米晶,高能Ti离子和一部分碳原子扩散到基体中,使得过渡层与基体的界面展宽,形成良好的界面混合,提高了DLC膜与基体的结合力。为了制备性能最优的DLC膜,对过渡层的制备参数进行了优化。随着过渡层沉积偏压、Ti靶输入电流和C靶功率的增大,活性粒子对基体的轰击和溅射作用增强。高能粒子对表面的轰击能够去除生长表面的杂质和弱键合原子,更有利于sp³键的形成以及得到更平整的表面。过渡层沉积偏压增大产生的辅助轰击效应,会加快界面处成分的扩散,有利于提高膜基间的结合力。随着Ti靶输入电流增大,DLC膜中的Ti含量也随之增多;Ti替代一个碳原子,造成平均配位数的减少,促使四配位的sp³键向sp²键转变。Ti靶电流过大时溅射下的大颗粒会形成富Ti区,成为局部腐蚀的阳极,而薄膜成为阴极,从而诱发局部腐蚀。C靶溅射产生浅注入现象,高能C离子注入到基体表层,薄膜的局部密度增加,引起压应力增大,从而促使sp³键的生成。当入射能量过大时,高能C离子在薄膜与基体界面进行扩散,恶化了薄膜的结合强度以及机械性能。综合上述结果,过渡层沉积偏压100V,Ti靶输入电流0.2A,C靶功率200W沉积的DLC膜,过渡层的Ti/C原子比为1,此时的DLC膜具有最优异的性能;粗糙度达到最小值2.11nm;硬度与弹性模量分别为17.6GPa和233.7GPa;在400mN正压力下磨损20分钟内仍然性能良好,摩擦系数为0.13:极化电阻值较未镀膜的铜基体提高2个数量级。采用最佳过渡层参数制备的DLC膜的热导率最大值为3.63Wm^-1K^-1;Ti/Ti_xC_y/DLC功能梯度材料可以强化铜基体的传热效果。更多还原

【Abstract】 In recent years,with society stride forward to electronic technology,automatization,and digital network information society.And copper are finding increasing applications in micro-electronics,micro-electro-mechanical systems（MEMS） and Hi-tech material applications.However copper has its material limitations.In particular,it has relatively low hardness,high oxidation and rate of wear,bad corrosion resistance which have severely limited its widespread applications.In this paper,aimed at difficulties of copper applications, Ti/Ti_xC_y/DLC has been proposed as functionally graded material to deposit on the copper substrate with different depositing methods,which intensify the adhesion between DLC films and copper substrate and improve the properties of copper.A graded intermediate layer design has been proposed prior to deposition of DLC by combining plasma enhanced unbalanced magnetron sputtering physical vapor deposition （PEUMS-PVD） and microwave electron cyclotron resonance plasma enhanced chemical vapor deposition（MW-ECR PECVD） techniques.Improvement in low adhesion between DLC films and copper substrate can be achieved by depositing the graded intermediate layer of Ti/Ti_xC_y、Si/Si_xN_y.The DLC films were smooth,dense and amorphous with typical diamond-like structure and thickness level was in a nanometer range.And it has excellent hardness and elastic modulus,much higher than substrate.In the experiment of Si/Si_xN_y/DLC films deposition,it was found that Si atom sputtering yield decreased,because of target poisoning phenomenon.So Ti was introduced as intermediate layer element to deposit DLC films on copper substrate to solve this problem.But there was element H in the intermediate layer,which held high residual stress and decreased the hardness and adhesion between the films and substrate.Ti/Ti_xC_y intermediate layer were prepared by PEUMS-PVD technique so as to avoid introducing H element,which reduced the stress concentration and improved the stability of intermediate layer.XRD and XPS analyses indicated that TiC nanocrystallines generated in the films,high-energy Ti ion and some C atoms diffused into the substrate which widened the interface between intermediate layer and substrate to make a nice interface mixing and improve the adhesion between DLC films and substrate.For acquiring the DLC films with excellent properties to protect the copper substrate,the experiment to make the best optimization parameter choice had been studied systematically. With the increase of intermediate layer deposition bias voltage,Ti target input current and C target power,bombardment of active radical around the substrate increased.The bombardment may wipe off any weak bond and impurity,be more conducive to sp³-bond come into being and get much smooth surface.Increase of intermediate layer deposition bias voltage and proper bombardment would accelerate the diffusion of interface components,which enhanced adhesion between films and substrate.When the Ti target input current was rised,the Ti content of DLC films increased too.Ti atoms substituted triply bonded carbon atoms,which would reduce the average coordination number of DLC films,and improved the transformation from sp³-bond to sp²-bond.The incidence of Ti ion with high energy leaded to the improvement of adhesion.At high value of Ti target input current,micro-cell corrosion would take place between the large granule Ti and films,the riched large granule Ti would become anode and the films become cathode of local corrosion.With shallow infusion caused by C target sputtering, ions with high energy penetrated into the coating of substrate causing internal pressure stress. This leaded to the increases of film density and formation of sp³ bonds.However,the ion of high energy diffused in the interface which deteriorated the adhesion and mechanism of the films,once the bombardment energy had exceeded a critical value.As a result,the best parameters for excellent performance of DLC films found were:intermediate layer deposition bias voltage of 100V,Ti target input current of 0.2A,C target power of 200W,and Ti/C ratio was 1.And the high quality DLC films with minimal roughness of 2.11nm was obtained at the aboved parameters,maximal hardness and elastic modulus of 17.6GPa and 233.7GPa were respectively achieved too.DLC films held excellent hardness suffering from the positive pressure of 400mN for 20 minutes,the coefficient of friction was only 0.13.And the polarization resistance of DLC films improved two orders of magnitude compared with copper substrate.The maximal value of thermal conductivity of DLC films with optimized parameter of graded intermediate layer was 3.63Wm^-1K^-1,which enhanced the heat transfer effect of copper substrate.更多还原