Piezo and Thermal Resistance Sensor Properties of Ni-ZrO2 Cermet Films On Silicon Substrates

用于传感器应用的9612122布坎南金属陶瓷(金属氧化物复合)薄膜需要高电阻温度系数(Tcr)、宽电阻范围(20-10K)和高压阻应变灵敏度。用MOD工艺在硅衬底上成功地制备了这种Ni-ZrO2金属陶瓷薄膜。在这一过程中分子团簇的形成为在这些难以制备的金属陶瓷薄膜中获得均匀的微结构提供了明显的优势。在还原气氛中控制烧结可以调节金属陶瓷薄膜的Ni相和电阻性能。金属陶瓷的导电性受颗粒大小、颗粒形态和孔隙率等关键微结构特征的控制。在所有情况下，必须形成穿过该结构的导电路径，以便具有具有低电阻和正TCR的主导金属行为。在金属陶瓷中，在渗流电导阈值附近，TCR和压阻都是有意义的。在此阈值下，随着绝缘子含量的增加，电阻增加了几个数量级，TCR由正变负，压阻规因数增加。在这个过渡区，正极TCR、负极TCR(NTC)和压阻传感器材料都可以在较小的体积百分比金属范围内生产出来。这项研究将对这一行为进行彻底的调查。Ni-ZrO2是一种两相复合体系，含有不与绝缘成分发生反应的非贵金属成分。因此，薄膜MOD Ni-ZrO2系统引起人们的兴趣有几个原因。在Ni-ZrO2薄膜金属陶瓷中增加ZrO2，可以设计出具有高TCR的高电阻薄膜。作者制备的薄膜具有3000-6800ppm/(C)的高TCR，体积含量在30-80vol.%Ni范围内。这些Ni-ZrO2薄膜的优点是：与硅兼容，薄膜厚度在微米范围内可控(0.2-L(M))，高强度，与硅、二氧化硅和A1203衬底的粘附性，并表现出压敏性。测量了MOD法制备的Ni-ZrO2金属陶瓷薄膜的压阻系数接近50的电阻变化。在拟议的工作中，将研究沉积过程的影响，包括基本的溶液化学。还将研究包括快速热退火(RTA)在内的烧结参数对Ni-ZrO2金属陶瓷复合薄膜电阻性能的影响，以期建立一个预测传感器性能的模型。***

9612122 Buchanan Cermet (metal-oxide composite) films for sensor applications require high temperature coefficient of resistance (TCR), wide resistance range (20-10k(), and high piezoresistive strain sensitivity. Such Ni-ZrO2 cermet films have been successfully prepared on silicon substrates by the MOD process. The formation of molecular clusters during this process offers distinct advantages in achieving homogeneous microstructures in these difficult to fabricate cermet films. Controlled sintering in a reducing atmosphere modulates the Ni phase and the resistive properties of the cermet films. Electrical conduction in cermets is controlled by key microstructural features such as grain size, grain morphology and porosity. In all cases, conductive paths must be formed through the structure in order to have dominant metallic behavior with low resistance and positive TCR. In cermets, both TCR and piezoresistance are of interest near the percolation conductivity threshold composition. At this threshold, as insulator content increaqes, resistance increases several orders of magnitude, TCR changes from positive to negative, and piezoresistive gauge factor increases. Positive TCR, negative TCR (NTC), and piezoresistive sensor materials can all be produced within a tight volume % metal range in this transition region. This behavior will be thoroughly investigated in this study. Ni-ZrO2 represents a 2 phase composite system containing a non-noble metal component that does not react with the insulative component. The thin film MOD Ni-ZrO2 system, therefore, is of interest for several reasons. Increased ZrO2 in the Ni-ZrO2 thin film cermet allows the design of higher resistance films with high TCR. Films fabricated by the author exhibit high TCR of 3000-6800 ppm/(C over Ni volume contents in the 30-80 vol.% Ni range. Advantages of these Ni-ZrO2 thin films are: silicon compatibility, controlled thickness in micron range films (0.2-l(m), high strength, and adherence to Si, SiO2 and A1203 sub strates, and demonstrated pressure sensitivity. Resistive changes indicating piezoresistive gauge factors approaching 50 have been measured for the MOD derived Ni-ZrO2 cermet films. In the proposed work the effects of the deposition process, including the underlying solution chemistry will be investigated. The effects of sintering variables, including rapid thermal annealing(RTA), on resistance properties in the Ni-ZrO2 cermet composite films will also be studied, with a view to developing a model for predicting sensor properties. ***