Study On Composition Analysis Of Thermocouple Alloy And Surface Temperature Measurement Of Sputtered Thin Film Growth

In the thin film preparation process,the thin film deposition temperature is an extremely critical parameter,which has a significant impact on the physical and chemical properties of the thin film,so it is of great significance to accurately measure the thin film deposition temperature.The film deposition temperature is divided into substrate temperature and film growth surface temperature.Because the traditional method of measuring the surface temperature of an object has defects in measurement accuracy and spatial resolution,it cannot be used to measure the surface temperature of thin film growth.However,thin film thermocouples have high measurement accuracy,small thermal inertia,small volume,high flexibility,and spatial resolution.It has the advantages of high efficiency and can test the surface temperature of film growth.Therefore,this paper designs and prepares X-type multilayer structure NiCr/NiSi film thermocouples,and takes magnetron sputtering Ti and Ti O₂ films as an example to study the surface temperature of film growth.Before using a thin film thermocouple to measure temperature,we must first understand its composition origin.However,due to the lack of a suitable composition unit model,the composition origin of thermocouple solid solution alloys has not yet been revealed.In order to solve the above problems,this paper carries out the following work:（1）Analyze the supercluster formula of binary solid solution alloys commonly used in the field of thermocouples by using the cluster plus connecting atom model.Then explore the origin of the composition of the thin film thermocouple.Based on the cluster formulas of face-centered cubic and body-centered cubic metals,the supercluster formulas of face-centered cubic and body-centered cubic solid solution alloys are established.Combined with the phase diagram in the service temperature range of the thermocouple,the theoretical optimal composition ratio of the solid solution alloy is given.Taking the K-type NiCr/NiSi thermocouple as an example,the theoretical optimal composition is Ni_89.477Cr_10.523（wt.%）/Ni_96.909Si_3.091（wt.%）,and the result is consistent with the composition Ni₉₀Cr₁₀（wt.%）/Ni₉₇Si₃（wt.%）,which theoretically reveals the optimal composition origin of solid solution alloys commonly used in the field of thermocouples.（2）Based on the analysis results of the optimal composition ratio of the K-type NiCr/NiSi thermocouple theory,NiCr/NiSi thin film thermocouples were prepared by DC pulse magnetron sputtering technology.Through the analysis of three thin film thermocouple calibration procedures,the standard calibration procedure of thin film thermocouples is determined.The relationship between the Seebeck coefficient of NiCr/NiSi thin film thermocouple and the change of film thickness was studied by using the standard method of thin film thermocouple.The results showed that as the thickness of NiCr/NiSi film increased from 400 nm to 2000 nm,the Seebeck coefficient of NiCr/NiSi thin film thermocouple increased from 7.32μV/℃to 13.36μV/℃.As the thickness of NiCr and NiSi films increases,the concentration of square electrons increases,which leads to a gradual increase in the Seebeck coefficient of NiCr/NiSi film thermocouples.The NiCr/NiSi thin film thermocouple composed of thicker NiCr film and thinner NiSi film shows a relatively high Seebeck coefficient.（3）Under the standard calibration procedure to calibrate the NiCr/NiSi thin film thermocouple,use the X-type multilayer structure NiCr/NiSi thin film thermocouple to study the surface temperature of the film growth by magnetron sputtering Ti and Ti O₂ thin films,and the magnetron sputtering The difference between the film growth surface temperature and the substrate temperature during the shooting process.Taking the Ti film as an example,the incident Ti atoms/ions convert the kinetic energy into the internal energy of the film on the growth surface of the film,and cause the surface temperature of the Ti film to grow at a steady state of 257.5℃,while the substrate temperature is 51.9℃;taking the Ti O₂ film as an example,Under the same conditions,in addition to the incident Ti/O atoms/ions converting the kinetic energy into the internal energy of the film on the film growth surface,the chemical heat released by the chemical bonding of Ti-O is also converted into the internal energy of the film,which comprehensively leads to the growth of the Ti O₂ film in a steady state.The surface temperature is 345.6℃,while the substrate temperature is 82.0℃,which means that the surface temperature of film growth is much higher than the substrate temperature.