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Why has wet etching almost disappeared in modern manufacturing processes? Uncover the truth behind it!
In the microprocessing industry, etching technology is an indispensable part, especially in the wafer manufacturing process. Traditionally, wet etching, also known as liquid phase etching, was the original etching method, most common before the 1980s. However, with the advancement of technology, this process has gradually been replaced by dry etching methods. So, why has wet etching almost disappeared in modern processes?
Basic principles of wet etching
Wet etching uses a liquid-phase etchant to remove material from the wafer surface. During this process, the wafers are immersed in solutions containing chemicals that are known to be corrosive to certain materials, such as silicon dioxide.
However, the main disadvantage of wet etching is that it often results in an isotropic etching effect, that is, the etching proceeds uniformly in all directions. This is certainly a problem for micromachining applications that require a high degree of precision and geometry.
Wet etching typically requires the disposal of large amounts of toxic waste and is difficult to control the etching depth and direction, making it nearly impossible to use in precision manufacturing.
The rise of dry etching
With the advancement of microelectronics technology, dry etching technology has gradually become mainstream. Dry etching, especially plasma etching, allows precise control of etch depth and shape, which is critical for modern wafer production. This technology can achieve anisotropic etching by adjusting the parameters of the plasma, that is, the etching rate is not uniform in different directions, and is very suitable for making deep and narrow structures.
Environmental and safety considerations
Another drawback of wet etching is its environmental impact. As environmental regulations become increasingly stringent, many companies are beginning to look for alternatives to reduce the harm they cause to the environment during their production processes. The use of wet etching involves a large number of toxic chemicals, which may pose a threat to the health of workers and the surrounding environment. In contrast, the dry etching process is usually performed in a closed system, reducing the risk of exposure to hazardous chemicals.
Technological progress and future trends
With the continuous improvement of processes, dry etching options are becoming more diverse and specialized, such as deep reactive ion etching (DRIE), which has shown advantages in manufacturing finer structures. In addition, dry etching can also specifically target certain materials by changing the gas composition, increasing its flexibility in a variety of applications.
Whether it is in terms of process effects or environmental impact, dry etching has clearly become the preferred technology in modern micromachining.
Conclusion
Although wet etching was once an important part of the micromachining process, as technology developed, dry etching took over due to its accuracy, protective measures and environmentally friendly features. As demand and technology change, what kind of revolution will micromachining technology usher in in the future?
