The Back Of The Power Transistor Metallization And Optimization Design

Power transistor back metallization process technology is one of the most important, especially for high voltage, current and large power transistor devices, the back metal layer will be the reliability of its higher demands. I am in the high-power transistor product reliability testing and application experiments appear in the die shear force is poor, delamination off the metal layer, saturated pressure drop, poor fatigue resistance, thermal resistance increases, and even transistors such as the failure of poor reliability situation, but there is also likely to use the same technology than small and medium to high power transistors, which metal layer on the back of high power transistors for analysis and hope to the original equipment and technology to find solutions based on.Analysis of metal layer adhesion on silicon substrates, derived metal layer adhesion and affect the reliability of factors.First recognize the type silicon surface stains and mechanism, and through effective pre-cleaning technology to get the clean silicon surface, to increase the metal film on a silicon chip adhesion.Further stress on the metal film systems research, to clarify the formation mechanism of the stress. Preparation of metal film of the process, the factors that affect the film stress, optimization of metal thin film production process conditions, lower metal film prepared by the internal stress. Transistor in the material differences between the linear expansion coefficient of large, by analyzing a variety of commonly used linear expansion coefficient of metallic materials proposed high-power transistors on the back of the structure with three metal layers to reduce the copper from the silicon film Dao package between the framework linear expansion coefficient difference, to control for different materials produced by stress, high-power transistors to improve the reliability of the back metal layer.Sputtering and evaporation of the advantages and disadvantages of the existing equipment considerations, experimental sputtering method using silicon film on the back of three metal layers of the preparation and adoption of effective heat treatment technology to further enhance the three layers of metal film adhesion and reliability. Finally these three metal layers of material selection, and the combination of layers of structural material, and the thickness of each layer of metal thickness at the two requirements, samples were divided into four groups. After four samples on the side shear force testing, empty rate detection, thermal fatigue test the reliability of the experimental test.There is a form of relationship betweenΔVbe and thermal resistance of the transistor under certain conditions.The value of thermal resistance can be calculated based on the algorithm by measuringΔVbe characteristics of the transistor.Conclusion Ti-NiV-Ag three metal layers as the back electrode technology can improve the reliability of high-power transistors, and in the original production equipment can optimize production costs brought under control.