Research On Characteristics Of Cutting Fluid For Ultra-thin Silicon Wafer And Resources Of Drained Slurry

In recent years, with the development of solar cells and semiconductor industry, the demand for one of the essential products of the cutting fluid in the wafer cutting has been increasing. Wafer cutting fluids used in the market can not only improve the cutting efficiency but also the safety and less pollution to the environment. In order to research the cutting fluid which conform to today's social philosophy of environmental protection, for the six properties of cutting fluid, such as cooling, scattered, cleaning, lubrication, rust and penetrate, by means of screening out the program one by one, the cutting fluid which is developed has excellent performance, in line with the requirements of the wafer cutting applications.Similarly, from the view of sustainable resources, wafer cutting will produce large amounts of drained slurry, and its recovery prospects are bright. The three main components in the drained slurry are cutting fluids, silicon carbide particles and silicon particles, which can be individually recycling or utilization, as a consequence, it can also save costs and resources.Cutting liquid with good performance is prepared from drained cutting liquid by solid-liquid separation of the drained slurry, carrying out decolorization, dehydration and removal of metal ion impurities. Conditions of decolorization are as follows. The mixture is stirred with 2% active carbon at 20℃for 1 hour first. Then it was stirred with 10% bleaching clay at 20℃for 30 minutes, while water is being removed. The conductivity of the cutting fluid after the ion exchange is reduced from 0.725ms/cm to 0.002ms/cm.The solid portion of the solid-liquid separation was washed with water and filtered for three times firstly. The liquid holdup of the solid portion after treated is investigated each time. After treated three times, the liquid content of the solid portion can be ignored, and the environmental pollution is reduced. Then, sodium silicate is generated by the reaction between the powder of solid portion and sodium hydroxide. It can be used for the preparation of low-modulus sodium silicate solutions, and the removal of silicon from silicon carbide particles can be achieved at the same time. The best conditions of the conversion rate for silicon are as follows: silicon particles at a concentration of 3%, temperature of 60℃and the reaction time of 90 minutes.The SEM can be used to observe the particle size distribution from silicon carbide particles and silicon particles. The model of the cylindrical hydrocyclone and of the long-conical hydrocyclone is both designed. Mixture model was respectively utilized for the three-dimensional numerical simulation of multiphase flow field in the two models. The results show that the long-conical hydrocyclone is more conducive to the separation of silicon carbide particles and silicon particles from the mixture slurry, and simulate that separation efficiency reach 90 percent. Experiments show that separation efficiency of the long-conical hydrocyclone reach 87 percent, which can be a good use of the separation of the silicon carbide particles and silicon particles from the mixture slurry.