In the field of semiconductor equipment precision parts processing, surface roughness is one of the core indicators for measuring part quality, and its control precision directly affects the performance, reliability, and service life of the equipment. Surface roughness not only concerns the appearance of the part but is also closely related to critical functions such as signal transmission efficiency, impedance matching, wear resistance, and sealing. For example, in high-speed digital circuits, excessive roughness on the copper surface can lead to signal scattering and reflection, increasing transmission loss; in precision mating surfaces, excessive roughness can cause contact stress concentration, accelerating wear. Therefore, semiconductor equipment precision parts processing has extremely stringent requirements for surface roughness control, necessitating a multi-dimensional approach encompassing processing technology, material selection, tool optimization, and environmental control.
Processing technology is the primary step in controlling surface roughness. Grinding, polishing, and electrical discharge machining (EDM) are widely used in semiconductor equipment precision parts processing. Grinding removes material through the micro-cutting action of high-precision grinding wheels, requiring the selection of appropriate wheel type and grit size based on the material characteristics of the part. For example, when machining high-hardness alloys, superhard abrasive wheels must be used, and grinding parameters must be optimized to avoid burns and cracks. Polishing further reduces surface roughness through a synergistic effect of chemical and mechanical processes, where the formulation and concentration of chemical additives are crucial to the final result. Electrical discharge machining (EDM) is suitable for complex-shaped parts, and by precisely controlling the current pulse parameters, nanoscale surface roughness control can be achieved.
Material selection also significantly impacts surface roughness. Precision parts for semiconductor equipment often use high-purity, highly homogeneous metallic materials, such as copper, aluminum, and stainless steel. The crystal structure, hardness, and heat treatment state of the material directly affect the cutting force and surface quality during machining. For example, copper alloys that have undergone special heat treatment have refined and uniformly distributed grains, which can significantly reduce the surface roughness after machining. Furthermore, surface pretreatment processes, such as sandblasting and cleaning, can effectively remove oxide layers and impurities, providing a good foundation for subsequent machining.
The geometry and material of the cutting tool are key factors in controlling surface roughness. In semiconductor equipment precision parts processing, the cutting edge angle, rake angle, clearance angle, and other parameters of the cutting tool must be precisely designed according to the part material and machining requirements. For example, increasing the tip radius can reduce cutting marks and lower surface roughness; while optimizing the secondary rake angle can suppress cutting vibration and improve surface quality. Regarding tool materials, superhard materials such as cemented carbide, ceramics, and diamond are preferred for semiconductor processing due to their high wear resistance and thermal stability. Diamond tools, in particular, can achieve atomic-level surface roughness control due to their extremely low coefficient of friction and excellent cutting performance.
The stability of the processing environment has a significant impact on surface roughness. Fluctuations in environmental parameters such as temperature, humidity, and cleanliness can alter the physical properties of materials, thus affecting the cutting process. For example, high temperatures can cause material softening, increasing cutting forces and worsening surface roughness; while high humidity can trigger material oxidation, leading to surface defects. Therefore, precision parts processing in semiconductor equipment must be carried out in a temperature- and humidity-controlled cleanroom, with continuous air purification systems to filter airborne particles and ensure environmental stability.
The application of online monitoring and closed-loop control technologies provides technical support for precise surface roughness control. High-precision measuring equipment such as laser interferometers and atomic force microscopes can acquire real-time three-dimensional morphological data of the processed surface and transmit the feedback information to the processing system. AI algorithms automatically analyze the causes of deviations by comparing actual data with the design model and adjust processing parameters to compensate for errors. For example, when processing ceramic mirrors in semiconductor lithography equipment, a closed-loop control system can monitor surface roughness changes in real time and dynamically adjust tool paths and cutting parameters to ensure that surface accuracy and quality meet design requirements.
Surface treatment processes, as the final step in precision parts processing for semiconductor equipment, play a decisive role in the final control of surface roughness. Chemical mechanical polishing (CMP) technology, through the synergistic effect of chemical etching and mechanical grinding, can achieve global planarization, reducing surface roughness to the nanometer level. Furthermore, mechanical strengthening processes such as shot peening and roll forming, by introducing residual compressive stress on the surface, can not only reduce roughness but also improve the fatigue strength and corrosion resistance of parts. For example, the surface roughness of semiconductor sensor sensitive elements processed by roll forming can be reduced to below Ra0.01μm, while the surface hardness increases by 40%, significantly extending the service life. Controlling surface roughness in semiconductor equipment precision parts processing is a complex system engineering project, requiring coordinated efforts across multiple stages, including process optimization, material selection, tooling design, environmental control, online inspection, and surface treatment. As semiconductor technology advances to 7nm and below processes, the requirements for surface roughness will become increasingly stringent. In the future, through new material development, intelligent algorithm iteration, and processing equipment upgrades, surface roughness control technology for semiconductor equipment precision parts processing will continue to advance, providing stronger support for the manufacturing of high-end semiconductor equipment.
