Process Optimization Of Copper Thin Film Prepared By Magnetron Sputtering For High Generation TFT-LCD

Various new flat panel display(FPD)led by liquid crystal display(LCD)has been rapidly developed since 2000.Compared to low-generation production lines,high-generation production lines have inherent characteristics and advantages in the production process of TFT-LCD panels.The depreciation cost of a single panel of the high-generation production line is lower when cutting the same size panel,which reflects the scale economy effect of investment.With the development of TFT– LCD to super-size,high driving frequency and high resolution,the size of LCD panel becomes larger.Therefore,the wiring length is bound to increase,which makes it impossible to reduce the resistance by reducing the wiring length.Only by increasing the area of the wiring can the resistance be reduced.There are two ways to increase the wiring area.One is to enlarge the line width,and the other is to increase the thickness of copper film.Since increasing the wiring area causes a decrease in the aperture ratio,high-resolution panels tend to adopt a method of increasing the thickness of the film.When the copper thickness needs to be increased from 300 nm to more than 880 nm,and the thick copper will lead to the technical problems of surface warpage and oxidation.Aiming at the optimization of thick copper warping,we propose several improvement methods such as reducing the heating temperature of the chamber,step-by-step deposition of the film layer,and adding cooling water device in the process chamber.The main results are as follows: 1)Reducing the heating temperature of the Heating chamber cannot effectively reduce the temperature of the substrate before deposition,and may cause problems such as the impurity gas on the glass surface cannot be absorbed in time;2)Step-by-step deposition of the film layer can increase the time of heat dissipation before the completion of the deposition,which has a certain improvement on the thick copper warping;3)The addition of the cooling water device in the process chamber can greatly reduce the rise of the heating plate temperature during film deposition and reduce the ambient temperature of the glass substrate,we can effectively alleviate the degree of warping of the glass substrate.The warpage of the whole composite film can be improved by changing the stress of the underlying film.The stress can be reduced by increasing the power and the pressure of film deposition,which makes the tensile stress of the pure molybdenum film become compressive stress and improve the warpage of the composite film.According to the optimization of thick copper oxidation,the experimental results show that the oxidation area of the copper film increases with the increase of heater temperature and the decrease of power.As the heater temperature increases,the initial temperature of the substrate surface increases,and the final temperature of the substrate surface also increases after the completion of film formation.Therefore,the oxidation of copper film becomes more obvious when the substrate comes into contact with cool dry air(CDA).With the decrease of film forming power,the deposition time required for depositing the copper film of the same film thickness increases,and the time for the substrate surface temperature to continuously rise during the film forming process increases,resulting in an increase in the temperature of the substrate surface after the film formation is completed.Therefore,the oxidation of the copper film is also more obvious.Therefore,the improvement of oxidation can be achieved by shortening the deposition time,increasing the pause time during the deposition process,and delaying the time of the film with high temperature exposed to oxygen.At the same time,in order to optimize the warping and oxidation of thick copper in actual industrial production,the feasibility of specific mass production conditions were also proposed.