The lithography machine is an indispensable equipment in the semiconductor manufacturing process, which enables the manufacture of integrated circuits by transferring the chip design pattern to the silicon wafer. The lens of the lithography machine is one of the most critical components, and its smoothness directly affects the resolution and quality of the chip. So, how smooth is the lens of the lithography machine?
First of all, we need to understand how the lithography machine works. Lithography machines project chip design patterns onto silicon wafers coated with photosensitive materials by using ultraviolet light sources, and then form the layers of the chip through steps such as chemical etching and heat treatment. In this process, the lens of the lithography machine needs to focus the light source into a very small spot of light to achieve high-precision pattern transfer. Therefore, the surface of the lens must be very smooth to guarantee the propagation and focusing of the light.
Specifically, the lens surface roughness requirements of lithography machines are very high. In general, the surface roughness of the lens of EUV extreme ultraviolet lithography is better than 50PM or less (1PM = 10 -12 meters), while the maximum mirror diameter of the latest generation EUV lithography machine is 12 meters, the surface roughness is only 20pm (root mean square), and the surface accuracy (the difference between the peak and the valley) is only 0Around 12 nanometers. In contrast, the diameter of a human hair is about 70 microns, which means that the smoothness of the lens surface of the lithography machine is dozens or even hundreds of times thinner than that of a human hair!
So, why do lithography lenses need such a high degree of smoothness?First of all, the smooth surface of the lens can reduce the scattering and reflection of light, which can improve the efficiency of light utilization and focusing. Secondly, the smooth surface of the lens reduces the presence of contaminants and impurities, which can adversely affect the quality of the sensor. Finally, a smooth lens surface can also reduce the complexity and cost of the optical system, improving productivity and reliability.
In order to achieve such a high level of smoothness, the lenses of the lithography machine employ a variety of advanced manufacturing techniques and materials. For example, the lenses of EUV EUV lithography machines are designed with a multi-layer structure, and the thickness and material of each layer are precisely controlled and optimized. In addition, a variety of sophisticated measuring and inspection equipment is used in the manufacturing process to ensure that the quality of each lens meets the requirements.
In addition to the technical challenges, the lenses of the lithography machine also need to face the effects of environmental factors. For example, in harsh working environments such as high temperature, high humidity, and high vibration, lenses are susceptible to contamination and damage. Therefore, in order to ensure the stability and reliability of the lens, the operation and maintenance of the lithography machine needs to be strictly managed and controlled.
In short, the lens of the lithography machine is one of the indispensable key components in the semiconductor manufacturing process, and its smoothness directly affects the resolution and quality of the chip. In order to meet the requirements of high precision and high quality, the lenses of the lithography machine use a variety of advanced manufacturing technologies and materials, and need to be strictly managed and controlled. Although the lens smoothness of the lithography machine is very high, it still faces many technical and application challenges that require continuous research and improvement.