多孔硅绝热缓冲层上MnCoNiO薄膜的生长及快响应特性机理研究

The thermistor with the fast response characteristic is mainly ceramic structure. Because the size of ceramic is close to the physical limit in the order of micron, it will limit the decrease of the response time of the component with high power consumption. The thickness of thin films thermistor is in the range of tens to hundreds of nanometers. Thin film thermistor with smaller size is easier to respond quickly to temperature. However, In the process of developing existing thin films into components, the thermal response of the thin film will be interfered by the thermal conduction of the substrate. In order to obtain the faster thermal response thin films, the adiabatic substrate must be designed as soon as possible. The project will research the growth of MnCoNiO thin films on silicon substrate with porous silicon adiabatic buffer layer by RF magnetron sputtering technology. By analyzing the lattice structure, micromorphology and electrical parameters of thin films, the lattice mismatch heterogeneity growth mode and electron transport regular pattern between the thin film and the substrate have been studied. Based on the relationship between substrate structure, electron conduction and response time, the effect of substrate structure on heat dissipation and heat capacity of materials has been concluded. Indeed, the mechanism of fast response of thermo-sensitive thin films have been revealed. The above research will obtain the thin films with optimum porous silicon insulation structure. It is expected to achieve the breakthrough on the fast response temperature measurement element of the NTC thin films. In addition, it covers the fast response temperature measurement needs of ocean applications.

具有快响应特点的热敏电阻以陶瓷结构为主，由于陶瓷尺寸在微米量级就已接近物理极限，因此会因功耗大而限制元件响应时间的进一步缩短。薄膜型热敏电阻具有小尺寸特点，更易实现对温度的快速响应。但现有薄膜被开发成元件的过程中，衬底的热传导会对薄膜材料的热响应构成干扰，因此亟需设计出绝热衬底材料，以保证生长在其表面的热敏薄膜具有快响应的特点。本项目采用射频磁控溅射技术，在设计有多孔硅绝热缓冲层的衬底表面生长MnCoNiO热敏薄膜。通过分析薄膜晶格结构、微观形貌和电学参数，研究膜在衬底表面的晶格失配异质生长模式和电子输运规律，探讨衬底结构-电子传导-响应时间之间的关系，总结衬底结构对材料热耗散与热容的影响规律，揭示热敏薄膜快响应特性机理。通过以上工作，获得具有最佳多孔硅绝热层设计的超快响应热敏薄膜，有望实现薄膜材料在快响应测温元件上的突破，满足海洋环境领域对温度快响应监测的需求。

项目以满足海洋领域对海水温度快响应监测的实际需求为出发点，在热敏薄膜材料制备中引入多孔硅绝热缓冲层，以此消减硅基衬底对薄膜材料的热传导干扰的影响，为进一步构筑海洋测温用热敏传感器芯片打下了技术基础。按照项目申请书中所提出的研究内容，研究人员重点开展了以下几方面的工作：（1）探究出多孔硅缓冲层上MnCoNiO薄膜的生长控制与性能调控方法：通过大量实验，确定了磁控溅射法制备热敏薄膜的最佳条件，并通过调整退火条件，实现薄膜热应力调控办法，获得具有良好结晶度、致密度、平整度和稳定电学性能的4英寸NTC热敏薄膜晶圆，经第三方检测其厚度均匀性优于98%；（2）明确了绝热缓冲层对热敏薄膜特性的影响规律，获得了薄膜结构对材料电子传导和热敏特性的影响规律：分别在普通硅基、30%和50%孔隙率的多孔硅衬底上生长了三种热敏薄膜，对比分析发现不同衬底上制备所得热敏薄膜材料的导电机制均满足小极化子跳跃导电模型，多孔硅缓冲结构的存在对于薄膜静态电学参数基本没有影响。（3）采用有限元分析方法对热敏薄膜进行温度-应力-电场耦合及多物理场仿真，发现当热敏薄膜器件中存在多孔硅绝热层时，其瞬态响应时间会从1.6s提升至2ms；然而实验结果表明，多孔硅缓冲层对器件响应时间的提升仅有3%，因此可得结论尽管多孔硅绝热缓冲层在热敏薄膜器件响应速度提升的过程中起到的关键作用，但影响热敏器件的热响应快慢的首要因素是由器件整体尺寸而决定的耗散系数。在本项目的支持下，研究团队在Journal of Alloys and Compounds, Ceramics International等杂志上发表SCI论文5篇，申请国家发明专利2项，其中1项获国家授权。项目负责人入选中科院青年创新促进会和新疆天山青年学者，并获得新疆科技进步一等奖1项，协助团队培养了硕士5名，独立培养硕士研究生1名。相关技术在集成式温度传感器芯片研制中获得应用，所开发的热敏薄膜晶圆制备方法已实现转化并产生实际销售。基于上述，项目按期圆满完成了预定的全部研究目标。