![]() ![]() As functions become more and more closely packed on the wafer and microscopic structures become smaller, a single particle can affect the etched shapes and current paths. Contaminating particles can block etching and cause defects in the final semiconductor devices. While acid baths work well for cleaning general contaminants from silicon wafer surfaces, ensuring low particle counts can be challenging. Megasonic Cleaning Can Deliver Improved Cleaning Performance The cost benefits and reduced environmental impact can be substantial, and the areas where Megasonic cleaning is used will have increased worker safety and reduced chemical exposure. Megasonic cleaning uses plain water or water with the addition of mild detergents. When Megasonic cleaning is used to replace some of the traditional cleaning steps, the use of chemicals is reduced. The cleaning intensity is strong enough to dislodge impurities and contaminants but will not damage the wafer surface or the microscopic structures that have been etched into it. The sound waves create microscopic cavitation bubbles that deliver a gentle scrubbing action against the surface of the silicon wafer. The transducer that is immersed in the cleaning solution converts the signal to sound waves in the cleaning tank. With Megasonic cleaning, a frequency generator produces an electric signal in the MHz range that is transmitted to a transducer. Reducing the use of aggressive chemicals can save money beyond their direct cost and can improve the environmental footprint of the semiconductor manufacturing facility. The possibility of leaks and the disposal of the waste chemicals represent environmental hazards that are continuously being mitigated with tighter regulations. In addition to the cost of the chemicals themselves, there are ongoing costs related to the storage, delivery, and disposal of these chemicals. The cleaning of silicon wafers after the completion of each semiconductor manufacturing step is accomplished by soaking the wafers in mixtures of chemicals including hydrochloric acid or sulfuric acid. Megasonic Cleaning Reduces the Use of Toxic Chemicals As a result, the technology can improve the operation of semiconductor manufacturing lines for semiconductor fabricators and research labs. Silicon wafers cleaned with Megasonic cleaning are completely clean with a reduced particle count. The technology can save time and money because it works quickly and does not require expensive chemicals. Megasonic cleaning uses high-frequency sound waves in the cleaning tank to remove contaminants and particles from the silicon wafers. The remaining traces of process chemicals or microscopic particles can disrupt the etching process and result in defective or low-quality semiconductor devices. When silicon wafers are cleaned between manufacturing steps, it is critical to remove all contamination from the wafer surfaces.
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