Overview
Hexachlorodisilane (Si2Cl6) is a chlorosilane compound consisting of two silicon atoms bridged by six chlorine atoms. As a key precursor in advanced material deposition, it plays a critical role in semiconductor fabrication processes where high-purity silicon-containing thin films are required. The compound was first synthesized in the early 20th century but gained industrial significance with the development of silicon-based electronics. In contemporary applications, hexachlorodisilane is classified as a specialty chemical with strict handling requirements due to its reactive nature. Its primary value lies in the efficient delivery of silicon atoms during chemical vapor deposition (CVD) processes, where it outperforms simpler chlorosilanes in certain applications requiring precise stoichiometry.
Physical and Chemical Properties
Hexachlorodisilane exhibits distinctive properties that dictate its handling and application. The liquid has a characteristic pungent odor and fumes in moist air due to rapid hydrolysis. Its molecular structure features a Si-Si bond length of approximately 233 pm, with Si-Cl bonds measuring about 202 pm, creating a stable yet reactive framework. Thermodynamically, the compound demonstrates a vapor pressure of about 10 mmHg at 20°C, making it suitable for vapor-phase deposition processes. Its heat of formation is -657 kJ/mol, indicating significant stability despite its reactivity. When heated above 300°C, it decomposes to form silicon tetrachloride and elemental silicon, a property exploited in certain deposition processes.
Main Applications
The semiconductor industry consumes approximately 80% of global hexachlorodisilane production, primarily for depositing silicon nitride (Si3N4) films used in transistor gates and dielectric layers. In atomic layer deposition (ALD) processes, it serves as a silicon source for creating ultrathin, conformal films with angstrom-level precision on complex geometries. Beyond electronics, the compound finds niche applications in specialized chemical synthesis as a chlorinating agent and silicon source. Research institutions utilize it for developing novel silicon-based polymers and nanomaterials. Some advanced optical coatings also incorporate hexachlorodisilane-derived layers for their specific refractive index properties.
Safety and Storage
Handling hexachlorodisilane requires rigorous safety protocols due to its pyrophoric nature and corrosive byproducts. Facilities must maintain oxygen-free environments (<1 ppm O2) during transfer operations, typically using nitrogen or argon purging systems. Secondary containment is mandatory for storage vessels to prevent environmental contamination in case of primary container failure. Emergency response plans should address potential hydrogen chloride gas release, requiring neutralization materials like sodium bicarbonate slurry. Long-term storage stability depends on maintaining temperatures below 30°C and rigorous exclusion of moisture—even trace amounts can initiate decomposition. Transportation regulations classify it as a Class 8 corrosive material (UN no. 2985) with additional hazardous chemical labeling requirements.
B2B Procurement Guide
Industrial buyers should prioritize suppliers with ISO 9001-certified production facilities specializing in electronic-grade chemicals. Key specifications include metal impurity levels (Fe <50 ppb, Na <10 ppb) and particle counts for CVD applications. Batch certificates should verify chlorine content (theoretical 79.1%) and provide gas chromatography purity data (>99.999% for semiconductor use). Packaging options range from 1kg stainless steel cylinders to bulk shipments in specialized isotainers. Lead times typically range from 4-8 weeks for standard grades, with premium purity variants requiring longer production cycles. Payment terms commonly involve 30-50% advance payments due to the high raw material costs and specialized handling requirements. Quality disputes should be arbitrated through third-party analytical labs specializing in chlorosilane analysis.
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