Fabrication And Electrical Properties Of The Mn_1.2Co_1.5Ni_0.3O₄ Thermal Chips And Thin Films Materials

Since the 21st century,with the development of micro-processing technologies such as micro-semiconductor processing,printed electronics and microelectronic devicefabrication,peopleareincreasinglydemandingtheintelligence,miniaturization and precision of temperature sensors.Conventional negative temperature coefficient（NTC）thermistors are mostly disc-shaped,rod-shaped and beaded which are large in size and difficult to combine with modern semiconductor processes.Therefore,it is urgent to prepare an ultra-thin,ultra-light chip type thermistors element having a volume advantage.This paper studies the preparation of thermal chips and thin film materials and their electrical properties.Mn-Co-Ni-O materials have high stability and excellent heat sensitive properties and are widely used in NTC thermistors.In this paper,Mn_1.2Co_1.5Ni_0.3O₄ was selected as the basic material for the preparation of chips and thin films NTC electronic components.The Mn_1.2Co_1.5Ni_0.3O₄ chips were prepared by casting method.The optimum process parameters of the prepared chips were investigated.The Mn_1.2Co_1.5Ni_0.3O₄ chips with different thicknesses（120μm,110μm,100μm and 90μm）were prepared.The structural morphology and electrical properties were analyzed in detail.Nano-sized Mn_1.2Co_1.5Ni_0.3O₄ thermistors thin films were prepared by RF sputtering.The optimum growth temperature and power of Mn_1.2Co_1.5Ni_0.3O₄film on porous silicon substrate were investigated.The effects of porous silicon substrates with different porosity（0%,30%and 50%）on the properties of Mn_1.2Co_1.5Ni_0.3O₄ film were studied.The specific research results are as follows:1.Mn_1.2Co_1.5Ni_0.3O₄ thermal chips were prepared by using the casting method.When the powder content in the casting slurry was 2 g,the binder content was 4wt%,the organic solvent content was 2 mL,and the casting speed was 7 mm/s,the prepared Mn_1.2Co_1.5Ni_0.3O₄ thermal ceramic chip had a high density,the chip was flat and its thickness was uniform.2.The morphology,electrical properties and response time of different thickness（120μm,110μm,100μm and 90μm）chips were compared.The grain size of 90μm thick chip was uniform,no obvious dislocation and its phase structure was a single-phase spinel structure similar to MnCo₂O₄.When the chip thickness was increased from 90μm to 120μm,?₂₅5 increased from 127.0Ω·cm to 449.7Ω·cm and the thermal constant B_25/505/50 increased from 3377.9 K to 3514.2 K.The ratio of Mn³⁺/Mn⁴⁺of 90μm thick chip was 0.70,the ratio of Mn³⁺/Mn⁴⁺of 120μm thick chip was 1.02.In addition,the 90μm thick chip thermistor response time is 0.83 s.3.The Mn_1.2Co_1.5Ni_0.3O₄ films were grown on porous silicon substrate using RF magnetron sputtering.The optimum substrate temperature during film growth was150°C and the optimum sputtering power was 250 W.High quality Mn_1.2Co_1.5Ni_0.3O₄films were prepared on porous silicon substrates with different porosity（0%,30%and50%）.With the increase of porous silicon porosity,the agglomeration phenomenon on the surface of the films is more obvious and has a relatively high B_25/505/50 value.