Zr基吸气剂薄膜的制备与性能研究

发布时间：2018-06-16 14:06

本文选题：吸气剂薄膜 + 直流磁控溅射　；参考：《北京有色金属研究总院》2016年博士论文

【摘要】：吸气剂是一种通过物理和化学作用吸收活性气体来维持和提升电真空器件的真空品质的特殊功能材料。随着电真空器件的微型化与集成化,对维持其可靠性、稳定性和长寿命的吸气剂技术提出了新的挑战。传统吸气元件由于体积大且需要高温激活,已很难在MEMS真空封装器件中直接应用,薄膜型吸气剂作为有效的解决方案受到了真空科学与技术业界的广泛关注。国外在真空封装用吸气剂薄膜领域的研究工作开展相对较早,在学术研究和工程应用方面均有较大进展。我国目前在真空封装用吸气剂薄膜方面的研究工作开展相对较少,具有自主知识产权的吸气剂薄膜技术与产品还鲜有报道,因此加强我国在该技术领域的自主创新研究工作具有重要的学术和工程意义。本文以Zr-Co-Ce吸气合金作为研究对象,采用磁控溅射法沉积了Zr-Co-Ce吸气剂薄膜,研究了影响薄膜结构和性能的关键工艺环节,探索了优化薄膜吸气性能的有效途径,并通过对薄膜激活过程研究,分析探讨了薄膜的激活机理,最后对薄膜的实用性能进行了评测。具体研究工作和主要结论如下:(1)采用磁控溅射技术在Si衬底上沉积了多孔ZrCoCe吸气剂薄膜,探讨了工作电源模式、衬底温度、溅射气压、沉积掠射角、工作气体流量等工艺参数对薄膜结构及吸气性能的影响。研究发现,直流(DC)磁控溅射较之射频(RF)磁控溅射更有利于制备多孔柱状结构ZrCoCe薄膜。衬底温度和溅射气压对薄膜的微观组织结构影响较为显著,相对较高的衬底温度和溅射气压更有利于获得多孔柱状结构的薄膜。随着沉积掠射角的增大,沉积过程中的原子阴影效应增大,薄膜的柱状组织随之增多。随着Ar气体流量的增大,薄膜的沉积速率增大,表面晶粒排列无序度随之增加,薄膜容易获得较高的比表面积。在衬底温度150℃、溅射气压3 Pa、掠射角70°、Ar气体流量45 sccm的工艺条件下制备ZrCoCe吸气剂薄膜获得了相对理想的吸气性能,300℃激活30min后对H2的初始吸附速率达到238 cm3·s-1·cm-2。(2)研究了衬底除气工艺对薄膜最终吸气性能的影响,结果表明衬底吸附的残余活性气体是导致薄膜激活过程中发生毒化的重要原因。设计并制备了在结构上分别具有阻挡层和保护层的ZrCoCe吸气剂薄膜,并研究了膜层结构对薄膜微观组织与吸气性能的影响。研究结果显示,预沉积于衬底表面的一层致密阻挡层,可以有效降低衬底残气导致的毒化效应,同时也有利于提高吸气薄膜的比表面积,获得更佳的吸气性能。沉积于薄膜表面的Ni保护层,能够有效降低ZrCoCe薄膜的表面氧化程度,改善薄膜的吸气性能。(3)基于MEMS真空封装的工艺特点,对所制备的ZrCoCe薄膜进行了实用性评测,主要研究了激活温度和重复激活对薄膜微观结构和吸气性能的影响,并对薄膜的抗清洗溶剂毒化和大气氧化能力进行了考察。结果表明,ZrCoCe薄膜可在300~400℃温度范围加热保温30 min实现激活。较低激活温度主要导致薄膜表面钝化层的还原,薄膜晶态结构变化不大,吸气性能相对较低;较高激活温度不仅能改变薄膜表面化学活性状态,还会影响其微观晶态结构,两者协同作用使得薄膜吸气性能获得大幅提升。经异丙醇和Ar+等离子体清洗处理后,ZrCoCe薄膜初始吸气速率分别提高了23%和57%。薄膜吸气性能随暴露大气时间的延长而呈现明显衰减趋势,暴露时间越久,性能衰减越严重。暴露大气时间超过50天后,薄膜初始吸气速率降至沉积态薄膜的30.6%。(4)首次结合XPS分析、四极质谱分析(QMS)及热力学计算对ZrCoCe薄膜的激活过程进行了研究,探讨了ZrCoCe薄膜的激活机理,为设计低温激活吸气剂薄膜提供了理论依据。研究发现,暴露过大气的ZrCoCe薄膜表面覆盖着H2O、CO2和碳氢化合物等,薄膜表面的Zr和Ce主要以氧化态存在,而Co则主要以低价态氢氧化物的形式存在。在薄膜的加热激活过程中,Zr的氧化物在300℃开始还原;激活过程还导致了薄膜表面金属态钴的偏析及亚表面锆的碳化物的生成。随着激活温度的升高,薄膜表面吸附态的H2O、CO2和碳氢化合物等气体逐渐发生脱附,200℃以上的主要脱附气体为H2,整个激活过程未发现脱附的O2;金属氧化物中的O主要以向薄膜内部扩散的方式而离开薄膜表面,从而实现氧化态向金属态或近金属态的转变。
[Abstract]:The absorbant is a special functional material for maintaining and improving the vacuum quality of an electric vacuum device by absorbing active gases by physical and chemical effects. With the miniaturization and integration of an electric vacuum device, a new challenge is put forward for the technology to maintain its reliability, stability and long life. It is difficult to be used directly in the MEMS vacuum packaging device. The film type suction agent is widely concerned in the vacuum science and technology industry as an effective solution. The research work in the field of vacuum packaging in the field of vacuum packaging is relatively early, and great progress has been made in the field of academic research and engineering applications. At present, there are relatively few research work in the field of vacuum packaging in our country, and there are few reports on the technology and products of the aspirant film with independent intellectual property rights. Therefore, it is of great significance to strengthen our own research on independent innovation in this field. This paper is based on Zr-Co-Ce suction alloy as research research. The Zr-Co-Ce getter film was deposited by magnetron sputtering. The key process factors affecting the structure and properties of the film were studied. The effective way to optimize the performance of the film was explored. The activation mechanism of the film was studied and the practical performance of the film was evaluated. The main research work and main conclusions are as follows: (1) a porous ZrCoCe getter film was deposited on Si substrate by magnetron sputtering. The influence of working power mode, substrate temperature, sputtering pressure, deposition angle, working gas flow rate on the structure and suction performance of the film was discussed. The study found that the DC (DC) magnetron sputtering was more than the sputtering. The frequency (RF) magnetron sputtering is more conducive to the preparation of a porous columnar structure ZrCoCe film. The influence of substrate temperature and sputtering pressure on the microstructure of the thin films is more significant. The relatively high substrate temperature and sputtering pressure are more favorable for obtaining a porous columnar structure film. With the increase of the deposition angle and the atomic shadow effect in the deposition process With the increase of the Ar gas flow, the deposition rate of the film increases, the disordering of the surface grains increases, and the thin film easily obtains a higher specific surface area. The ZrCoCe getter film is prepared under the substrate temperature of 150 C, the sputtering pressure of 3 Pa, the grazing angle 70 degrees, and the Ar gas flow rate of 45 SCCM The relatively ideal suction performance was obtained. The initial adsorption rate of H2 at 300 C was reached to 238 cm3. S-1. Cm-2. (2). The effect of the substrate degassing process on the final gas absorption properties of the film was studied. The results showed that the residual active gas adsorbed by the substrate was an important cause of the toxicity of the film during the activation process. The effect of the membrane structure on the microstructure and the suction performance of the film is studied in the structure of the ZrCoCe. The results show that a dense barrier layer deposited on the substrate surface can effectively reduce the toxic effect of the substrate residual gas and also improve the ratio of the absorption film to the substrate. The Ni protection layer deposited on the surface of the film can effectively reduce the surface oxidation of the ZrCoCe film and improve the gas absorption performance of the film. (3) based on the technological characteristics of the MEMS vacuum packaging, the practical measurement of the prepared ZrCoCe film is carried out, and the activation temperature and the reactivation of the film are mainly studied. The effects of microstructures and inspiratory properties were investigated, and the anti cleaning solvent toxicity and atmospheric oxidation ability of the film were investigated. The results showed that the ZrCoCe film could be activated at 30 min at the temperature range of 300~400 C. The lower activation temperature was the main cause of the passivation layer on the film surface. The higher activation temperature can not only change the chemical activity state of the film surface, but also influence the microstructure of the film. The synergism of the two causes the film absorption performance to be greatly improved. After the isopropanol and Ar+ plasma cleaning, the initial gas absorption rate of the ZrCoCe film increases by 23% and the 57%. film absorption performance with the storm, respectively. The longer the exposure time shows the obvious attenuation trend, the longer the exposure time, the worse the performance attenuation. The initial suction rate of the film to the deposited film is reduced to 30.6%. (4) 30.6%. (4) for the first time, and the activation process of ZrCoCe film is studied by quadrupole mass spectrometry (QMS) and thermodynamic calculation. The activation mechanism of the ZrCoCe film provides a theoretical basis for the design of the active absorption film at low temperature. It is found that the surface of the ZrCoCe film exposed to the atmosphere is covered with H2O, CO2 and hydrocarbons. The Zr and Ce on the surface of the film mainly exist in the oxidation state, while the Co is mainly in the form of low valence hydroxide. During the living process, the oxide of Zr begins to reduce at 300. The activation process also leads to the segregation of cobalt on the surface of the film and the formation of the carbides of the subsurface zirconium. With the increase of the activation temperature, the adsorbed H2O, CO2 and hydrocarbon of the film surface gradually degenerate, and the main desorption gas above 200 c is the whole activation. The O2 is not found in the process, and the O in the metal oxide leaves the surface of the film mainly in the way of diffusion in the film, so as to realize the transition from the oxidation state to the metal state or the near metal state.
【学位授予单位】：北京有色金属研究总院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TB383.2

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