Research On Thermal Properties Measurement System Of Thin Films

Micro-nanometer thin film materials are widely used in MEMS (Micro-Electro-Mechanical systems). It's very important to have an comprehensive understanding of the thin films thermal properties for MEMS thermal design. In general, thermal properties of micro-nanometer thin films are different from those of published bulk materials because of the significant size effects come from quantum or surface effects. To improve the measurement accuracy, kinds of measurement methods have been proposed for different materials and structures in the past.A general thermal properties measurement system is usually set up by separated instruments, and operated by hand. The measurement process is complicated and trivial. To meet the needs of convenient and accurate measurements, an automatic test system for thermal properties of thin films is studied by combining the advantages of virtual instrument test platform. The system can be used to measure heat capacity of thin films based on the differential scanning calorimetry and thermal delay time method, to measure thermal conductivity of thin films based on the micro-bridge static method. The hardware and software design of the system has been completed. The instrument controlling, data acquisition and analysis, display and storage capabilities are integrated in the system.Parameter settings and data in-out of function generator, sourcemeter, temperature controller are carried out by a personal computer through a GPIB bus. The response signal of calorimeter collected by oscilloscope is transfered to the PC through the USB bus. Heat capacity or thermal conductivity of thin films under test can be obtained from the data processing based on the given measurement methods. The software design of the system is realized by LabVIEW8.6 and provide a friendly man-machine interface for operators.Thermal conductivity of a cantilever which is combined by SiO2 thin-film and polysilicon thin-film has been measured by the system, then the heat capacity of indium and tin films has also been measured. The experimental results are in accordance with the theoretical values, and the entire test systems are running well.