| HS Code | 287493 |
| Chemical Name | Tetramethylsilane (4MS) |
| Chemical Formula | Si(CH3)4 |
| Molecular Weight | 88.22 g/mol |
| Cas Number | 75-76-3 |
| Grade | Electronic/EL Grade |
| Purity | >=99.999% (typically 5N) |
| Appearance | Colorless clear liquid |
| Density | 0.646 g/cm³ at 20 °C |
| Melting Point | -99 °C |
| Boiling Point | 26.7 °C at 760 mmHg |
| Flash Point | -28 °C (closed cup) |
| Refractive Index | 1.358 at 20 °C |
| Solubility In Water | Insoluble |
As an accredited Tetramethylsilane (4MS) Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in high-purity stainless steel cylinders under inert nitrogen to preserve electronic-grade quality. Quantity: 100 mL per cylinder. |
| Container Loading (20′ FCL) | Load 20′ FCL with UN-approved steel drums of Tetramethylsilane (4MS), nitrogen-blanketed, securely blocked, grounded, and labeled for flammable liquid transport. |
| Shipping | Tetramethylsilane (4MS) Electronic/EL Grade ships as UN2749, a Class 3 flammable liquid. Because of its extreme volatility and low flash point, it requires UN-certified pressurized containers, inert blanketing, temperature control, and strict Dangerous Goods labeling. Transport is restricted to authorized carriers, with complete documentation for semiconductor-grade purity handling. |
| Storage | Store Tetramethylsilane (4MS) Electronic/EL Grade in tightly sealed, clean stainless steel or compatible containers under inert gas. Keep in a cool, dry, well-ventilated area away from heat, ignition sources, and oxidizers. Maintain low temperature to minimize vaporization and prevent contamination, ensuring purity and stability. |
| Shelf Life | Shelf life is typically 12 months from manufacture when stored sealed, cool, dry, and away from ignition sources. |
In front-end silicon-carbon-nitride barrier integration, electronic/EL-grade tetramethylsilane is vapor-drawn from a stainless steel canister held at 20–25 °C through an electropolished gas line heated to 45 °C, avoiding the bubbler level and carrier-gas instability that limits low-vapor-pressure organosilanes. A 300 mm single-wafer PECVD chamber with dual-frequency excitation at 13.56 MHz high frequency and 350 kHz low frequency is operated at 3.0–6.0 Torr, with an electrostatic chuck temperature of 350–400 °C and a showerhead-to-pedestal gap of 350–600 mil. Mass flow controller set points are 150–400 sccm 4MS, 300–900 sccm NH3, and 1,200–2,500 sccm He, giving an NH3:4MS flow ratio of 2:1 to 4:1. Below a 2:1 ratio the film retains excess methyl groups, the refractive index falls below 1.85 at 633 nm, and copper diffusion barrier performance degrades after 500 h of bias-thermal stress at 2 MV/cm. Above a 4:1 ratio the film shifts toward silicon nitride character, the dielectric constant exceeds 5.2 at 1 MHz, and tensile stress rises above 120 MPa, producing line wiggling in 7 nm-node test arrays. The downstream production process includes a post-deposition anneal at 400 °C in nitrogen for 30 min, followed by reactive-ion etching to open vias through the SiCN layer. Purity qualification requires ICP-MS detection limits of ≤1 ppb per metal, Karl Fischer coulometry at ≤0.5 ppm H2O, and laser particle counting with 0.1 µm sensitivity. Chemical delivery modules are evaluated against SEMI S2-0815 and process risk is assessed under SEMI S10-1108, with wafer handling zones controlled to ISO 14644-1:2015 Class 3. The terminal product is the copper/low-k BEOL wafer with a 15–50 nm SiCN double-function barrier and etch stop layer.
| NH3:4MS ratio | Refractive index at 633 nm | Dielectric constant at 1 MHz | Residual stress (MPa) |
|---|---|---|---|
| 2:1 | 1.88 | 4.7 | +80 tensile |
| 3:1 | 1.93 | 4.9 | +40 tensile |
| 4:1 | 1.97 | 5.2 | +10 tensile |
A silicon-rich silicon carbide hard mask is deposited directly on the interlayer dielectric prior to spin-on carbon and photoresist coating in high-aspect-ratio contact formation for 3D NAND and DRAM storage node contact etch. The 4MS-based film is processed in a 250–350 °C PECVD chamber at 4.0–8.0 Torr with 100–250 sccm 4MS, 600–1,200 sccm He, and 0–150 sccm H2, yielding a hydrogen:4MS flow ratio of 0–0.8:1. Hydrogen addition above 0.8:1 strips methyl groups aggressively and raises the wet etch rate in 100:1 dilute HF above 5 nm/min; omitting hydrogen leaves residual methyl groups that increase dry etch residue after mask opening. The deposited film, typically 50–150 nm thick, has a density of 1.8–2.2 g/cm3 and a compressive stress tunable from -100 MPa to -400 MPa through low-frequency RF power adjustment. In the downstream production process, the wafer receives a spin-on carbon layer, a silicon oxynitride anti-reflection layer, and a photoresist; the SiC hard mask is opened in a CF4/CHF3/O2 plasma, and the mask selectivity over amorphous carbon in O2 ash is maintained above 15:1. Equipment compliance for mask removal and chamber cleaning is aligned with SEMI S2-0815, exhaust abatement is validated for unreacted 4MS and silane byproducts, and particle contamination is controlled to ISO 14644-1:2015 Class 3 in the wafer handling zone. The terminal product is a patterned wafer at dielectric etch stage, where the SiC hard mask is removed before metallization.
Deposition of porous SiCOH from tetramethylsilane and alpha-terpinene uses a 250–350 °C single-wafer PECVD chamber at 2.5–6.0 Torr. Flow settings are 200–600 sccm 4MS, 50–150 sccm O2, 1,000–2,000 sccm He, and 0–150 sccm α-terpinene porogen, placing the porogen-to-4MS ratio at 0.15:1 to 0.35:1 and the oxygen-to-4MS ratio at 0.10:1 to 0.35:1. The oxygen partial pressure acts as a hard cliff: above an O2:4MS ratio of 0.35:1, Si-CH3 termination is oxidized, post-UV k rises above 3.2, and Young’s modulus falls below 6 GPa because carbon cross-linking is lost. After deposition, the wafer moves under vacuum to a broadband UV cure module held at 400 °C for 5–10 min in helium, removing the porogen and producing pores smaller than 2 nm. Film properties after cure are dielectric constant 2.55–2.85 at 1 MHz, hardness 1.0–1.5 GPa, Young’s modulus 6–10 GPa, and residual tensile stress 40–60 MPa. Dielectric constant is measured with a mercury probe according to ASTM D150-19; adhesion to the SiCN cap is checked by four-point bending; and porogen decomposition outgassing is monitored by residual gas analyzer. Published empirical data for exact 4MS/α-terpinene interaction under dual-frequency excitation remains limited, so chamber-specific requalification is required before high-volume use. The downstream production process is a dual-damascene copper/low-k integration sequence in which the porous layer is capped, etched, and degassed at 350 °C before barrier/seed deposition. The terminal product is the interlayer dielectric in 28 nm and below logic interconnects, with porous SiCOH film thickness from 40 nm to 80 nm per metal level.
Graphite wafer carriers and susceptors in metalorganic chemical vapor deposition of GaN and SiC are exposed to hydrogen at temperatures above 1,000 °C, and uncoated graphite generates particulates that reduce epi yield. A 4MS-derived silicon carbide coating is formed in a hot-wall low-pressure thermal CVD furnace with graphite components prebaked at 900 °C in argon. The reactor is held at 950–1,150 °C and 50–250 Torr; gas flows are 0.8–2.0 slm 4MS, 12–30 slm H2, and 8–20 slm Ar, giving a 4MS molar fraction of approximately 0.02–0.05. Coating rate increases from 0.8 µm/h at 950 °C to 3.5 µm/h at 1,150 °C, and a process time of 5–20 h builds a 20–80 µm dense beta-SiC layer. The downstream production process includes furnace cooling to 200 °C under argon, ultrasonic cleaning in deionized water, drying with filtered nitrogen, and final annealing at 1,100 °C under argon to densify the surface. Component release is blocked if dye penetrant testing according to ASTM E1417-21 shows crack or pore indications; surface particle cleanliness is verified in an ISO 14644-1:2015 Class 5 cleanroom using a laser particle counter above 0.3 µm; outgassing at 800 °C is measured by residual gas analyzer and must remain below 1 × 10-7 Pa·L/s for total hydrocarbons. The terminal product is a SiC-coated graphite susceptor, wafer carrier, or preheat ring qualified for MOCVD GaN and SiC epitaxy chambers.
Fan-out wafer-level packaging requires a moisture barrier directly over copper redistribution lines where temperature is limited by polyimide or PBO dielectrics to 180–220 °C. The 4MS-based PECVD film is deposited at 2.0–5.0 Torr and 180–220 °C with flow settings of 80–200 sccm 4MS, 500–1,000 sccm He, and 0–100 sccm NH3, producing an NH3:4MS ratio of 0–0.8:1. Thickness is 100–300 nm, and low-frequency power is adjusted so residual tensile stress remains below 100 MPa, preventing copper line rupture in serpentine test structures. At 85 °C/85% RH, the barrier delays copper dendrite formation on 10 µm / 10 µm line/space test vehicles to beyond 1,000 h when capped with polyimide; uncapped regions show edge ingress. The downstream production process is integration into a 200 mm or 300 mm fan-out line: polymer via opening, plasma desmear, PECVD barrier deposition, lithographic opening of bond pads, and solder bump formation. Reliability testing follows JEDEC J-STD-020E moisture sensitivity level 1 preconditioning plus unbiased temperature/humidity bias; adhesion is checked by ASTM D3359-23 cross-cut tape test after 85 °C/85% RH soak. The terminal product is a fan-out wafer-level package wafer with a moisture-resistant silicon carbide-based barrier over copper redistribution metal, which then continues to die placement and molding.
For via-sidewall dielectric deposition, chamber pressure is held below 0.7 Torr to increase mean free path before 4MS and NH3 dissociate. Through-silicon via liner deposition applies a thin silicon carbide dielectric from 4MS onto via sidewalls with aspect ratios up to 10:1 and depths of 50–100 µm. The PECVD process uses 100–200 sccm 4MS, 100–300 sccm NH3, and 800–1,200 sccm He at 250–300 °C and 0.3–0.7 Torr; the NH3:4MS ratio is held between 0.8:1 and 1.5:1. Step coverage at the via bottom is measured by cross-sectional SEM and remains above 40% for 8:1 aspect-ratio vias but falls below 20% at 10:1 when pressure exceeds 0.7 Torr, due to surface recombination and shadowing. The downstream production process occurs after Bosch or laser drilling and before copper barrier/seed deposition; the SiC liner must pass post-anneal at 400 °C in nitrogen to ensure no film cracking at via mouths. Compliance assessment uses SEMI S2-0815 for equipment safety and SEMI S10-1108 for process risk, with chamber particle control at ISO 14644-1:2015 Class 4. The terminal product is a through-silicon via wafer with SiC liner for 2.5D interposer or 3D stacked memory, before copper electroplating and CMP.
Competitive Tetramethylsilane (4MS) Electronic/EL Grade prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615365186327 or mail to admin@ascent-chem.com.
We will respond to you as soon as possible.
Tel: +8615365186327
Email: admin@ascent-chem.com
Flexible payment, competitive price, premium service - Inquire now!
Supplied as a low-boiling liquid with a normal boiling point of 26.6 °C at 101.325 kPa, Tetramethylsilane (4MS) Electronic/EL Grade is a carbon-bearing silicon precursor with the molecular formula Si(CH3)4, CAS 75-76-3, and molecular weight 88.224 g/mol. The material is qualified for front-end wafer fabrication where plasma-enhanced chemical vapor deposition films of silicon carbide, silicon carbonitride, and silicon oxycarbide serve as hard masks, etch stop layers, and copper diffusion barriers. Typical certificates of analysis state a purity of 99.999% (5N) for Electronic Grade and an extended trace-metal budget for EL Grade, with individual alkali and transition metal concentrations at ≤0.1 ppb and total metals at ≤1 ppb. Lot release data normally include moisture below 1 ppm and chloride below 0.5 ppm. These thresholds are not cosmetic: transition-metal contamination in the low-ppb range can alter leakage current and charge-to-breakdown in low-k dielectric stacks, while chloride must be excluded from copper-compatible process flows. Physical property data include a density of 0.648 g/cm³ at 20 °C by ASTM D4052-18 and a vapor pressure near 78.6 kPa at 20 °C; the closed-cup flash point is approximately −27 °C by ASTM D56-21a. The product is supplied under supplier-specific model designations, commonly 4MS Electronic Grade or 4MS EL Grade, and is not represented by a single part number across gas manufacturers.
Electronic-grade qualification is defined less by total GC area per cent than by the elemental residuals that survive incineration and enter the wafer environment. For 4MS, the relevant control parameters are total metals, mobile ions, moisture, chlorides, and high-boiling hydrocarbon homologues. The table below summarizes a representative specification envelope; lot-specific values vary by filling facility, and the certificate of analysis should be consulted for the exact lower limits.
| Parameter | Analytical method | Representative Electronic/EL Grade value |
|---|---|---|
| Purity (GC-FID area per cent) | GC-FID | ≥99.999% (5N) |
| Total trace metals | ICP-MS | ≤1 ppb |
| Individual alkali/transition metals | ICP-MS | ≤0.1 ppb |
| Moisture | FTIR | ≤1 ppm |
| Chlorides | Ion chromatography | ≤0.5 ppm |
| Hydrocarbon homologues | GC-MS | ≤10 ppm |
| Density at 20 °C | ASTM D4052-18 | 0.648 g/cm³ |
| Vapor pressure at 20 °C | Static cell | 78.6 kPa |
| Boiling point at 101.325 kPa | Distillation | 26.6 °C |
| Closed-cup flash point | ASTM D56-21a | −27 °C |
Process integration of 4MS starts with canister and gas-panel selection. Because the normal boiling point is 26.6 °C, a cylinder held at 20 °C develops a vapor pressure near 78.6 kPa; this is adequate for mass-flow-controlled vapor draw, but the transport line must be held above the source temperature to avoid condensation. In production installations, 316L electrophished stainless steel with 10 μin Ra internal roughness, metal-diaphragm regulators, and helium leak rates below 1×10⁻⁹ Pa·m³/s are specified. Line temperature is held between 30 °C and 40 °C, with an upper limit of 45 °C to reduce decomposition and protect canister valve seats. Direct liquid injection is an alternative; in that configuration the density of 0.648 g/cm³ and the low viscosity require the liquid mass flow controller to be calibrated with 4MS-specific data rather than with silane or dichlorosilane performance curves.
At high vapor draw rates, the cylinder can cool by evaporative loss, causing pressure drift and unstable mass flow. Gas cabinets therefore use cylinder warmers or heat jackets set at 25–30 °C; heater failure can lower the source pressure and produce transient film-thickness drift on the wafer. When direct liquid injection is used, the vaporizer is maintained between 40 °C and 60 °C to ensure complete volatilization without prolonged exposure to temperatures that promote premature ligand fragmentation. Carrier gas pressure must be stable within ±0.1 bar to prevent liquid slugging into the process chamber.
Unlike silane, which is pyrophoric and can ignite spontaneously in ambient air, 4MS is flammable but not pyrophoric. Its vapor is denser than air and can accumulate in pit areas or gas cabinets; ventilation and electrical classification follow NFPA 70 Article 501 for hazardous locations, and static-discharge protection follows NFPA 77. Process abatement for 4MS does not require a wet acid scrubber because no hydrogen chloride is produced. However, when co-fed with NH3 or N2O, the exhaust train must be designed for ammonia or oxides of nitrogen, and the thermal oxidizer must be sized for the full flammable gas load.
In PECVD barrier films, 4MS is typically co-fed with nitrogen, ammonia, helium, or hydrogen at substrate temperatures from 200 °C to 400 °C and chamber pressures from 0.5 Torr to 10 Torr. The plasma source is normally a capacitively coupled parallel-plate configuration at 13.56 MHz, sometimes combined with a low-frequency component at 350 kHz to control ion bombardment and film stress. The four methyl substituents supply a high intrinsic carbon fraction that increases Si–C bond density and fluorocarbon etch resistance. The same carbon content can raise dielectric constant and reduce breakdown strength if deposited without adequate nitrogen or hydrogen dilution. Representative bounds in 200 mm and 300 mm chambers are 50–500 sccm 4MS, 500–2000 sccm dilution, showerhead-to-wafer spacing of 8–20 mm, and RF power density of 0.5–3 W/cm². Film properties vary with tool geometry, and published data for a specific chamber configuration are limited; qualification is performed on the target dielectric stack.
Film stress, dielectric constant, and etch selectivity are coupled. Increasing RF power density from 0.5 W/cm² to 3 W/cm² densifies the film and may improve hardness, but it can also raise compressive stress and shift the dielectric constant upward. For etch-stop and barrier films, the dilute hydrofluoric acid etch rate is a practical control metric; published values for organosilicon SiCN films exposed to 100:1 DHF at 23 °C range from 0.5 nm/min to 10 nm/min depending on nitrogen incorporation. Because this range is broad, the process is not transferred by refractive index alone; films must be measured for thickness, stress, leakage, and composition after tool qualification.
| Precursor | Formula | Si–H sites | Carbon atoms per Si | Pyrophoricity | Principal non-carbon by-product | Typical film classes |
|---|---|---|---|---|---|---|
| 4MS | Si(CH3)4 | 0 | 4 | No | Hydrocarbon fragments | SiC, SiCN, SiCO |
| 3MS | (CH3)3SiH | 1 | 3 | No | Hydrogen, hydrocarbon fragments | Low-k SiCO, SiC |
| Silane | SiH4 | 4 | 0 | Yes | Hydrogen | SiO2, SiN |
| Dichlorosilane | SiH2Cl2 | 2 | 0 | No | Hydrogen chloride | SiN, epitaxial Si |
From a materials compatibility standpoint, 4MS is substantially less reactive toward moisture than chlorosilane precursors; however, the electronic-grade canister cannot tolerate repeated exposure to ambient air because trace oxygen can form oxygenated by-products in the headspace over thermal cycling. Canisters are vacuum-baked and passivated before filling, and valves are equipped with PTFE or bromobutyl seals. Nitrile rubber is unsuitable for prolonged contact with the low-density liquid because swelling can compromise seal integrity. Moisture intake during changeouts is controlled by purge sequences using high-purity nitrogen, with measured moisture at the point of supply below 1 ppm.
Compared with trimethylsilane, 4MS removes the Si–H reduction site and replaces it with a fourth methyl group, shifting the molecular Si:C ratio from 1:3 to 1:4. The absence of Si–H lowers the probability of silanol formation in oxygen-containing plasma, but it also reduces gas-phase nucleation and may require higher RF power to maintain deposition rate. Trimethylsilane is often selected for low-k dielectric films where Si–H assists crosslinking; 4MS is more frequently selected for etch stop layers and silicon carbonitride barriers where carbon retention and etch selectivity dominate. Unlike oxygen-containing precursors such as dimethyldimethoxysilane, 4MS contains no oxygen in the ligand sphere; oxygen must be supplied by a co-reactant if silicon oxycarbide is required. Published direct substitution data on identical chambers are limited, so the selection is normally confirmed by split-lot deposition and reliability testing.
The primary chemical incompatibilities of 4MS are strong oxidizers, halogenated solvents, and uncontrolled ignition sources. Combustion can generate silica fume, carbon monoxide, and carbon dioxide; the flammable liquid and vapor classification follows a closed-cup flash point of approximately −27 °C determined by ASTM D56-21a. Where regulatory documentation requires flammability-limit testing, ASTM E681-09 is used. Storage temperature is kept below 40 °C to limit canister pressure. At 20 °C, the vapor pressure is approximately 78.6 kPa; at 26.6 °C, the vapor pressure reaches 101.325 kPa, and above that temperature the material enters a boiling condition unless the canister is designed for the resulting pressure. Dry chemical or carbon dioxide suppression is specified for fires; water is not recommended because the liquid is immiscible and lighter than water, potentially spreading the burning product. Transfer through ungrounded plastic tubing is prohibited because electrostatic discharge can ignite the vapor without an external flame.
Tetramethylsilane is also known in analytical chemistry as the 0 ppm reference for 1H NMR spectroscopy; however, the Electronic/EL Grade supply chain is distinct from NMR-reference reagent grade. The electronic-grade material is controlled for trace metals, moisture, particle performance, and packaging compatibility in wafer manufacturing, whereas the analytical-reagent grade is certified for chemical-shift consistency. The Electronic/EL Grade is not used as an NMR reference without verification because stabilizer and packaging residues may differ from analytical reagent requirements.
