Semiconductor cleaning process

In the semiconductor manufacturing industry, the importance of the cleaning process is self-evident. As the industry continues to advance to nanoprocesses, the requirements for wafer surface cleanliness are becoming more stringent. In the manufacturing process, cleaning steps are complex but indispensable, accounting for about one-third of the entire chip manufacturing process. Cleaning is not only about the yield of the chip, but also about electrical performance and long-term reliability. Therefore, we must have a deep understanding of this vital link to ensure an efficient and environmentally friendly production process.

The importance of cleaning processes

Manufacturing processes such as diffusion, deposition, ion implantation, etc. need to be cleaned before and after the process. The goal of cleaning is to remove contaminants from the chip, including particulate matter, organic matter, metal contaminants, and oxides. All kinds of fine dust, chemicals and even the production equipment itself can become a source of pollution. Each step of cleaning requires specific equipment, chemicals and process conditions to complete.

Wet cleaning technology

Wet cleaning is the most commonly used method in semiconductor cleaning. From the introduction of RCA cleaning technology, we know that this is a standard industrial cleaning process, proposed by the Radio Corporation of America in the 1960s. RCA cleaning is primarily done through a combination of standard cleaning fluids 1 and 2, both based on hydrogen peroxide, which remove particles, metals and organic matter, respectively. The cleaning principle involves chemical oxidation and electrochemical repulsion.

Cleaning process optimization and challenges

With the increasing improvement of cleaning processes, new mixed solutions such as SPM (H2SO4/H2O2) and diluted hydrofluoric acid (DHF) have been introduced. However, these cleaning methods also face many challenges, such as the concentration of solution components, solution temperature and other factors can affect the final cleaning effect. In addition, the fluidity of the solution during the cleaning process is as important as the washing of the wafer surface.

Innovative cleaning technology

At present, saving resources and improving efficiency have become a development trend. Diluted chemical cleaning and IMEC cleaning, both of which focus on reducing the use of chemicals and deionized water while optimizing the life of the solution, achieve more environmentally friendly and economical results. For example, diluted HPM is just as effective as conventional HPM and can also remove metal contaminants, while reducing total chemical consumption by 14%.

In order to improve cleaning efficiency, single wafer cleaning has become a new trend. It is expected to significantly improve product yields and reduce costs by reducing the risk of cross-contamination. In addition, the application of dry cleaning technology is becoming increasingly popular, although it can not completely replace wet cleaning, but dry cleaning has its unique advantages, such as no residual waste liquid and more suitable for specific local treatment.

Importance of drying process

The drying process after cleaning is also critical. Wafers must be dried immediately to avoid oxidation or water stains. Drying techniques such as Marangoni drying and Rotagoni drying remove moisture by precise drying methods to keep the chip clean.

Future direction

In the face of increasingly complex processes and continuously upgraded equipment, semiconductor cleaning is facing more challenges. Researchers are working on more efficient cleaning techniques, such as combining megatonic waves, to remove finer particles. In the field of high-precision manufacturing processes, cleaning processes will undoubtedly become a hot spot for innovation and development.

Semiconductor cleaning, as an important part of the chip manufacturing process, its progress and innovation are directly related to the future of the entire industry. Environmentally friendly and efficient cleaning methods will be the key to promoting the sustainable development of the industry. As the technology matures further, it is expected that the semiconductor manufacturing industry will be able to maximize resource utilization and minimize environmental impact while ensuring chip quality and performance.

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