Study On The Performance Of Etching Solution For ITO And Cu/Mo Film In The Industry Of TFT-LCD

In the process of thin film transistor liquid crystal display(TFT-LCD)array,ITO and Cu/Mo are widely used due to their high conductivity,low material cost and good response to graphics.Precise etching is a very important processing unit in the production process of TET-TCD.The film taper angle should be between 40° and 60°after etching.otherwise causing unquafied products.At present,the commonly used ITO etching solution is mainly composed of sulfuric acid,nitric acid and acetic acid.The Cu/Mo etching solution is mainly hydrogen peroxide and sulfuric acid system,The type of film and the thickness of the composite metal layer will increase the difficulty of accurately controlling the etching rate.Therefore,it is of great significance for the production of ITO,Cu,Mo and other metal films to develop etching solutions with excellent performance.In this experiment,the change in corrosion rate of ITO,Cu and Mo under different etching conditions was studied by the relative characterization methods and electrochemical test methods,and the corresponding corrosion mechanism was explored to achieve a stable control method for obtaining qualified taper angle.The effect of single acid and mixed acid on ITO corrosion was studied by control variation method.The experimental results show that the increase of sulfuric acid concentration in ITO etching solution is more conducive to the dissolution of tin,and the increase of nitric acid concentration is more conducive to the dissolution of indium.Acetic acid has the function of stabilizing acidity and buffer solution.The optimization concentrations of sulfuric acid,nitric acid and acetic acid were determined to be 5%,16% and 10% for etching ITO oxide film,respectively.In the investigation of the corrosion of copper and molybdenum,the corrosion rates of copper and molybdenum in hydrogen peroxide and sulfuric acid systems were first studied.According to the etching results under different conditions and the relative XPS characterization results,the coexistence of hydrogen peroxide and sulfuric acid solution is a prerequisite for the corrosion of copper and molybdenum.Hydrogen peroxide oxidizes the metal to form oxides,and then sulfuric acid dissolves the oxides.Considering the instability of hydrogen peroxide,nitric acid was used instead of hydrogen peroxide.It is found that the nitric acid/sulfuric acid solution has not only good performance for etching the Cu/Mo film but also high stability.On the basis of the above results,the corrosion behavior of the Cu/Mo film on glass was investigated.By adjusting the concentration of different components of the etching solution,the effective etching of the Cu/Mo thin film was realized.After optimization,it was found that the formula of hydrogen peroxide/sulfuric acid system was as follows: hydrogen peroxide 5%-11%,sulfuric acid 1%-7%,ammonium dihydrogen phosphate 0.5%-2% and additive PSP 0.3%-1%.And nitric acid 1%-7%,sulfuric acid 25%-35%,additive PSP 0.5%-2%.The two optimized kinds of etching liquids can effectively control the corrosion taper angle of Cu/Mo glass substrate within the required range.the comparison between the two etching solution showed that the former could lead to a cleaner surface than the later,while the nitric acid/sulfuric acid system etching solution was more stable to preserve.