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The semiconductor industry is the core of the modern electronics industry, while the silicon materials industry is the foundation of the semiconductor industry. However, the manufacturing process of silicon wafers will inevitably be contaminated by dust, metals, organic matter, and inorganic matter. Meanwhile, the quality of silicon chip cleaning can seriously affect the performance, reliability, and yield of devices. In recent years, with the continuous improvement of the level of integrated technology, the size of devices has been continuously reduced, the quality requirements for silicon wafers get increasingly high, and the impact of pollutants on devices has become more prominent. Therefore, effective cleaning processes have played a critical role in the silicon wafer manufacturing process.
Figure 1. The wafer used in semiconductor industry
Traditional cleaning methods consist of chemical cleaning, ultrasonic cleaning, and vacuum high temperature treatment. Among them, the vacuum high temperature treatment method is carried out after chemical cleaning and ultrasonic cleaning processes, so that the object to be cleaned is in a vacuum environment, without being subject to the secondary contamination. The gas and solvent molecules adsorbed on the surface have increased volatility, making it easier to remove. As the name suggests, the chemical cleaning method makes use of chemical reagents or organic solvents to cause impurities to detach from the surface of the object to be cleaned through chemical reactions or dissolving effects with impurities and dirt on the cleaned surface to achieve the cleaning purpose. Among them, physical measures such as ultrasound or heating, may also be used to assist in cleaning. On the other hand, the ultrasonic cleaning method is to peel off foreign matter from the workpiece by increasing mechanical force based on chemical cleaning. Under the high-frequency mechanical vibration of ultrasonic waves, the tiny bubble core in the cleaning solution expands rapidly and then suddenly closes. Upon closing, a shock wave is generated. This dynamic process of expansion, closure, and vibration is called the “cavitation effect” of ultrasonic waves. The “cavitation effect” provides sufficient energy for the chemical and physical reactions during the cleaning process. At the same time, the instantaneous high pressure generated continuously affects the surface of the cleaned workpiece, and causes the foreign matter dirt to peel off quickly on the surface of the cleaned object and in the gaps. The ultrasonic cleaning effect is good and the operation is simple, which can not only reduce the possibility of secondary contamination due to complex chemical cleaning processes, but also achieve cleaning purposes for complex devices. Due to its stronger cavitation effect, low-frequency ultrasound can clean larger particles, but it is also easy to damage devices.
Figure 2.The cover-type wafer cleaner manufactured by Siansonic Technology
Megasonic cleaning equipment preserves the advantages of ultrasonic cleaning, overcomes its shortcomings, and cleans silicon wafers by combining chemical reactions with chemical cleaning agents. However, due to the higher frequency, bubbles such as ultrasonic cleaning are not formed, but high-speed fluid waves continuously affect the surface of the workpiece, thereby forcibly removing pollutants adhering to the surface of the workpiece. As a result, there is no damage to the surface of the workpiece. Moreover, megasonic cleaning equipment can remove particles smaller than 200 nanometers on the surface. In comparison to traditional ultrasonic cleaning, megasonic cleaning equipment is suitable for the cleaning industry with a higher degree of cleanliness. Megasonic cleaning equipment has become an effective device for silicon wafer cleaning
After years of research and development, Siansonic has successfully developed megasonic cleaning equipment up to 3000kHz. It is committed to getting rid of the situation where megasonic cleaning equipment is monopolized by the developed countries such as the US and Japan, and has contributed to the localization of domestic semiconductors.
