Studies On The Key Technologies In Fine Atomization CMP Of TFT-LCD Glass Substrate

TFT-LCD has lots of the advantages. It has lifelike images, light weight and low power consumption, and it is very environmental. It is mainly used in televisions, notebook computers, mobile phones, monitors and other equipment. Glass substrate is one of the important elements in TFT-LCD display panel and it is related to the resolution ratio,transmittance and other characteristics of the display panel. Light transmittance, low density,high elastic modulus and high physical and chemical stability make it difficult to process. As the degree of integration increases and the linewidth reduces, the demand of machining accuracy and surface quality of glass substrate is higher. Ultrasound fine atomization chemical mechanical polishing can improve the usage of the polishing slurry and the surface quality of the workpiece, and reduce processing costs. In this paper, fine atomized slurry chemical mechanical polishing method is applied to the processing of TFT-LCD glass substrate.Preparation of efficient polishing slurry, the process of fine atomization CMP and material removal mechanism of glass substrate are studied in order to provide technical support for the processing of TFT-LCD glass substrate.Firstly, the system of fine atomization chemical mechanical polishing and its working principle are introduced. Then the composition of slurry and their effects in polishing process are analyzed. The most suitable material of each polishing fluid component was chosen by experiment considering material removal rate, surface roughness and dispersion stability as index.Through orthogonal test, the content of each component in polishing slurry was optimized, and the influence degree of each component on material removal rate and surface roughness was analyzed. Then material removal mechanism of glass substrate was analyzed.The best parameter combination is as the following: the mass fraction of Ce O2 was 4%, the mass fraction of Si O2 was 10%, p H was 11 and the mass fractions of surfactant was 1%.The effect of fog flow, the polishing pressure and the rotating speed of the polishing pad on material removal rate and surface roughness was studied through single factor experiment.The best parameter combination was obtained, and the influence degree of each component on material removal rate and surface roughness was analyzed through orthogonal test. The best parameter combination is as the following: the polishing pressure was 8 psi, the flow rate of polishing fluid was 8.3 m L/min and the rotating speed of the polishing pad was 65 r/min.Under the same test conditions, two tests of polishing TFT-LCD glass substrate were conducted. One of them used atomizing polishing method and self-made polishing slurry, the other one used conventional polishing method and purchased polishing slurry. The results of the two tests were compared after polishing. It showed that the material removal rate ofatomizing polishing method was slightly lower than that of the conventional CMP, but the surface roughness of atomizing polishing method after polishing was better than that of the conventional method, and the consumption of polishing slurry by atomizing polishing method was 1/10 compared with traditional polishing. The cause may be that after polishing slurry is atomized into micron-sized liquid particle, its diffusion, adsorption and chemical activity become stronger, and the chemical reaction with the surface of glass is enhanced. Aggregate phenomenon in polishing slurry reduces after the atomization, therefore surface roughness after polishing is good.