How do semiconductor equipment seals maintain good sealing performance in high vacuum environments?
Publish Time: 2025-11-13
In semiconductor manufacturing processes, especially front-end processes such as physical vapor deposition, chemical vapor deposition, ion implantation, and photolithography, the extreme conditions place almost stringent demands on the airtightness of each component. Even a tiny gas leak or material outgassing can lead to process contamination, wafer defects, or even batch scrap. As a key component ensuring the integrity of the vacuum chamber, semiconductor equipment seals must maintain long-term, stable, and reliable sealing performance under multiple harsh conditions, including high vacuum, high and low temperature cycling, highly corrosive gases, and plasma radiation.1. Material Selection: Low Outgassing and High Chemical Stability are KeyIn high vacuum environments, ordinary rubber or plastics will continuously "outgas" due to internal adsorption of gases or volatile components, compromising the vacuum level. Therefore, semiconductor seals generally use special elastomers or polymers with ultra-high purity and low outgassing rates. Perfluoroether rubber and modified polytetrafluoroethylene are the most typical examples. FFKM's molecular structure contains almost no C-H bonds, exhibiting excellent resistance to plasma, strong acids and alkalis, and high temperatures. Its total mass loss under ultra-high vacuum is less than 0.1%, far superior to conventional fluororubber. While PTFE is a thermoplastic material, its extremely low surface energy and near-zero moisture absorption make it an ideal choice for static sealing.2. Structural Design: Precise Matching and Stress OptimizationThe geometry of the seal directly affects the contact pressure distribution and sealing effect. In high-vacuum flange connections, metal seals or elastomer O-rings with precision groove designs are commonly used. The O-ring compression ratio is typically controlled between 15% and 30%—too low a ratio will fail to form an effective sealing interface, while too high a ratio can easily lead to permanent deformation or stress relaxation. Furthermore, to prevent "cold flow," some sealing structures incorporate retaining rings or use irregular cross-sections to improve extrusion resistance. In dynamic sealing areas, multi-lip or bellows designs are used to maintain airtightness while ensuring flexibility of movement.3. Clean Manufacturing and Surface Treatment: Eliminating Particulates and ContaminantsThe entire production process of semiconductor seals is carried out in a high-cleanliness environment to prevent the adhesion of dust, metal ions, or organic contaminants. After molding, post-processing such as ultrapure water rinsing and high-temperature vacuum baking is required to further remove residual volatiles. Some high-end products also undergo plasma or chemical passivation treatment on the sealing surface to reduce surface roughness and enhance inertness, reducing the risk of side reactions with process gases.4. System Integration and Leak Detection Verification: A Closed-Loop Reliability System from Components to the Whole SystemEven if an individual seal performs excellently, improper installation or uneven flange surfaces can still lead to leaks. Therefore, during the assembly of semiconductor equipment, strict control is exercised over flange parallelism, surface roughness, and bolt preload. After assembly, it is ensured that the entire system meets the vacuum pressure standards required by the process.On the "invisible battlefield" of high vacuum, semiconductor equipment seals, though small, are crucial. Through the deep integration of materials science, precision engineering, and clean manufacturing, they construct an invisible yet indestructible barrier in extreme environments. These unsung "sealing guardians" ensure the pristine environment for nanoscale chip manufacturing, supporting the precise operation and continuous innovation of the global semiconductor industry.
