| Popis: |
Single layer of aluminum film was sputter deposited on to (100) oriented 4 inch silicon wafer to study effect of film thickness, D.C. power and sputtering gas pressure on the film stress. The as-deposited stress appeared to be increasing as film thickness increases and argon pressure decreases. Thermal stress originated from difference in CTE and temperature variation during and after sputtering seems to be a main factor in room temperature sputter deposited aluminum films. From observation of temperature-stress behavior, it was found that the pure aluminum film has an elastic modulus of 56GPA and compressive yield strength of -100MPA. The yield strength was improved to about -175MPA by alloying with 3wt.%Ti. Titanium alloying also proved to be useful in extending linear elastic region before plastic deformation occurs. However, it was hard to determine the stress level with buckling phenomena of ring/beam microstructures because of imperfections such as stress gradient and thermal deformation. In stead, those diagnostic microstructures could be applied to give an information on whether a plastic deformation was introduced or not in a structure of specific dimension. |
