Based On The Back Of The Power Transistor Metallization Sputtering Process Design

The two manufacturing methods of high-power transistors on the back of the electrode are generally sputtering and evaporation. The evaporation deposition thin film is featured with convenience, easy operation, fast speed to become the membrane, and high efficiency, which is the most widely used technology in thin film deposition. The shortcoming of this technology is that the thin film cannot combine well with the substrate, and the craft duplication is not good enough. Compared with the evaporation technology, the sputtering technology develops later, but it has the advantages of the good combination of the thin film and the substrate, high purity and good compactness of the thin film. Therefore the sputtering coating gradually substitutes the evaporation coating in wide application. However, in sputtering, the substrate might heat up by radiation of the plasma and with a low deposition rate. Especially in the preparation of high-power transistor layers of metal electrodes, if certain process parameters are under improper control in the sputtering process, the problems like layers between metal, big patch holes, thin metal layers will emerge, leading to low reliability of the transistors in use.In this thesis, the effects of the parameters in the sputtering process on the back metallization of high-power transistors and its properties have been analyzed. The main contents are as follows:1.The effects of gas flux on the thickness and hollow were studied in detail. The mechanism of the formation of hollows was analyzed. The results show that the increase of the gas flux will lead to increasing the number of hollows.2. The effects of the vacuum on the film quality were studied in detail. It was found that the increase of vacuum in sputtering process makes for high reliability of films.3. The effects of the sputtering power on film thickness were investigated. It was found that the film thickness not always increase with the sputtering power in linear.4. The effects of the chrome - nickel-chromium-silver and titanium- nickel-vanadium– silver, the two back of the metal structure on the drop experimental were studied. It can be seen that the impact strength of titanium- nickel-vanadium- silver is better than that of chromium - nickel-chromium-silver.