In the ultra-high vacuum (UHV) environment of semiconductor photolithography machines, even trace amounts of material outgassing can trigger catastrophic contamination. Under irradiation by 13.5 nm extreme ultraviolet (EUV) light, small organic molecules can undergo pyrolysis and deposit onto the surfaces of multilayer mirrors; this leads to a reflectivity drop exceeding 50%, effectively rendering optical systems—valued in the tens of millions—irredeemably obsolete. By virtue of its characteristics of "ultra-low outgassing" and "high vacuum stability," phenyl raw rubber has emerged as the ideal material for internal sealing and vibration-damping components within photolithography machines, thereby constructing a "zero-contamination" vacuum barrier for nanoscale lithography processes.

The core advantage of phenyl raw rubber lies in the "high bond energy and dissociation resistance" inherent in its molecular chains. In the complex environment of an ultra-high vacuum (<10⁻⁷ Pa) combined with exposure to EUV light and high-energy particles, the Si-O backbone of ordinary silicone rubber (with a bond energy of 365 kJ/mol) is susceptible to scission via photolysis or particle bombardment, resulting in the generation of volatile low-molecular-weight substances. In contrast, phenyl raw rubber incorporates phenyl ring structures into its main chain. By leveraging the p-π conjugation effect between the phenyl ring's π-electron cloud and the silicon atoms, it boosts the Si-C bond energy from 285 kJ/mol to 305 kJ/mol. Simultaneously, the rigid structure of the phenyl rings inhibits the expansion of the molecular chain's free volume. This dual reinforcement—encompassing both bond energy and structural integrity—ensures that its Total Mass Loss (TML) remains below 0.5% after baking at 150°C for 24 hours. This performance is vastly superior to that of ordinary methyl silicone rubber (which typically exhibits a TML > 2%), thereby eliminating the risk of vacuum contamination at its very source.

Regarding the control of vacuum outgassing constituents, phenyl raw rubber demonstrates a unique "selective barrier" capability. Its phenyl side groups are capable of forming transient dipole interactions with small polar molecules (such as H₂O and CO₂), thereby inhibiting the desorption and release of these adsorbed environmental contaminants. During the vacuum pumping process within a photolithography machine, the water vapor release rate of phenyl raw rubber seals stands at a mere 10⁻⁸ Pa·m³/s—a reduction of two orders of magnitude compared to traditional materials. Furthermore, the cross-linked network of phenyl-based raw rubber can be engineered—specifically by modulating the vulcanization system (e.g., via platinum-catalyzed addition curing)—to eliminate residual catalyst ions (such as amines or peroxide decomposition products). This prevents these impurities from migrating to the mirror surface in a vacuum environment, thereby averting the formation of a "chemical contamination layer."
Moreover, the "vacuum dimensional stability" inherent to phenyl-based raw rubber resolves issues of mechanical failure under ultra-high vacuum conditions. Under a pressure differential of 10⁻⁷ Pa, conventional elastomers are prone to developing microporous defects caused by internal gas expansion, which can lead to seal failure. Phenyl-based raw rubber, however, possesses a free volume fraction of less than 15%; its volume shrinkage in a vacuum environment is controlled to within 0.1%, and its long-term compression set remains below 5% (tested at 200°C for 70 hours). This characteristic combination of "low deformation and high resilience" enables the material to serve a dual function in the micro-vibration isolation systems of lithography machine magnetic-levitation stages: it maintains nanometer-scale positioning precision while simultaneously preventing the introduction of additional particulate contamination caused by material creep.

From the perspective of material purity, the "semiconductor-grade" manufacturing process for phenyl-based raw rubber achieves unparalleled control over metal ion content. Through fully enclosed polymerization reactions and molecular distillation purification, the levels of alkali metals and heavy metals—such as sodium, potassium, and iron—are kept below 1 ppb, a figure significantly lower than the requirements stipulated by the SEMI F57 standard. This ultra-high purity characteristic prevents photo-induced metal migration under vacuum ultraviolet (VUV) irradiation; in accelerated aging tests spanning 2,000 hours, the increase in metal contamination on silicon wafer surfaces adjacent to the phenyl-based rubber remained below 1×10¹⁰ atoms/cm², thereby safeguarding the yield of the lithography process.
From mirror support structures to wafer stage sealing assemblies, phenyl-based raw rubber is emerging as the "invisible guardian" of ultra-high vacuum systems in lithography machines, distinguished by its comprehensive advantages: "enhanced molecular bond energy, minimal vacuum outgassing, and ultra-high purity." It serves not only as a critical material for resolving vacuum contamination issues but also, through breakthroughs in microscopic molecular design, provides a fundamental guarantee for pushing the precision limits of semiconductor manufacturing.