A Study Of Removal Techniques Of Contamination On Si Wafers In Microelectronics

With the rapid development of science and technology, the integrated degree improves fast and character size of devices minishes ceaselessly. The demand of impurities on substrate is more and more strict. The surface state of substrate and cleanliness are the most important factors that would affect the quality and reliability of devices. There are many procedures involve cleaning step such as oxidization, extension, diffusion, photofabrication and global complanation in the fabrication sequence of ULSI. The most time of cleaning is 80 times. Recently, cleaning should remove not only organic matter on silicon surface, but also the particles of millimicron order and ppt metallic ions. So new types of cleaning solution and cleaning technology adapted to ULSI should be invented.The general cleaning method that be used all over the world is using I, II, III solutions. Because I, II, III solutions have high cleaning efficiency, favorable cleaning effectiveness and soluble products. But it has many problems that can't be solved by itself. So insuring the flatness of silicon wafer and improving the cleaning efficiency are emphasis of research. The improved cleaning method has been searched out by means of experiment. This cleaning method can attain ideal cleaning performance.Now people attach importance to the cleaning of silicon grinded wafer. There are a lot of carborundums and silicon powders on the wafer surface because grinded wafer are grinded by carborundum and corresponding depth are remove in the sequence of grinding. After grinding there are plenty of carborundums and silicon powders enchase in the damaged layers. So there are many difficulties in later processes. According to experimentation we find that using organic base, permeate agent and surface active agent under the condition of ultrasonic would attain achieve better cleaning effective.Further study has been introduced in this article. It is very important that removing the residual liquid crystal in fabrication of liquid crystal display screen. Otherwise, the residual liquid crystal would corrode the electrodes and destruct the whole devices. The cleaning performance is good by use of freon but the environment would be destroyed. Freon is the material that should be substitute immediately by the state. The troubles of aquifer cleaning are long cleaning time and low efficiency. A new improved method of aquifer cleaning can reduce the cleaning time to 3-5min. The cleaning efficiency has been improved greatly.