| HS Code | 222351 |
| Chemical Name | Perfluoropropane |
| Chemical Formula | C₃F₈ |
| Molecular Weight | 188.02 g/mol |
| Cas Number | 76-19-7 |
| Un Number | 2424 |
| Grade | Electronic/EL Grade |
| Purity | ≥99.999% |
| Appearance | Colorless, odorless, non-flammable, compressed or liquefied gas |
| Boiling Point | -36.7 °C at 1 atm |
| Melting Point | -183.6 °C |
| Critical Temperature | 71.9 °C |
| Critical Pressure | 2.68 MPa |
| Vapor Density | 6.6 (air = 1) |
| Solubility In Water | Practically insoluble |
As an accredited Perfluoropropane (C₃F₈) Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Perfluoropropane (C₃F₈) Electronic/EL Grade, 47L cylinder, high-pressure seamless steel, ultra-high purity, with CGA 660 valve. |
| Container Loading (20′ FCL) | Perfluoropropane (C₃F₈) electronic grade is loaded as pressurized gas cylinders, secured upright in a 20-foot container with proper ventilation. |
| Shipping | Perfluoropropane (C₃F₈) Electronic/EL Grade is shipped as a liquefied compressed gas in high-pressure seamless steel cylinders or ISO tanks. Shipments require leak-proof valve protection, secure upright restraint, and compliance with hazardous materials regulations. Exclude moisture and contaminants; handle with proper ventilation and qualified personnel. |
| Storage | Store Perfluoropropane (C₃F₈) Electronic/EL Grade in a cool, dry, well-ventilated area, away from heat, ignition sources, and direct sunlight. Keep cylinders secured upright, with valve caps in place, and isolated from oxidizers. Use appropriate leak detection and monitor oxygen levels due to potential asphyxiation. Maintain temperatures below 52°C and follow compressed gas safety protocols. |
| Shelf Life | Stable for 24 months when stored in sealed containers, protected from moisture, heat, and contamination. |
Perfluoropropane C3F8 Electronic/EL Grade is deployed in the clearing of silicon dioxide, silicon nitride, and silicon oxynitride residues from plasma-enhanced chemical vapor deposition chambers. The gas is selected over C2F6 in 300 mm wafer fabrication where higher fluorine radical density per molecule and shorter clean time per accumulated film thickness are required. Compliance for this use is anchored to SEMI C3.57 for perfluoropropane electronic grade, which defines assay, moisture, oxygen, and halogenated hydrocarbon residual limits, with typical acceptance at 99.999 vol% minimum assay and trace metals below 10 ppbw for each element. Gas-phase analysis is performed by gas chromatography with pulsed discharge helium ionization detection, moisture by cavity ring-down spectroscopy, and trace metals by inductively coupled plasma mass spectrometry after impinger sampling. In a representative remote plasma clean on a dual-station PECVD platform, the gas blending ratio is 25–40 vol% C3F8 in argon/oxygen, with typical flows of 800–1,400 sccm C3F8, 2,800–4,200 sccm O2, and 600–1,000 sccm Ar at chamber pressure 2.5–4.0 Torr. The downstream production sequence consists of PECVD deposition of undoped silicate glass using TEOS or silane-based silicon nitride at wafer temperatures from 250 °C to 400 °C, after which remote plasma source dissociation of C3F8 generates atomic fluorine, CFx radicals, and COF2 intermediates. The fluorine converts solid Si–O and Si–N films into volatile SiF4 and nitrogen oxides, which are evacuated through a heated foreline and scrubbed by a dry abatement system. High-flow draws require cylinder heating or a temperature-compensated vaporizer to avoid pressure drop caused by vaporization cooling. Optical emission spectroscopy on the 703.7 nm fluorine line and residual gas analysis at mass-to-charge 85/86 for SiF4 provide endpoint termination. Terminal outputs include advanced logic, dynamic random-access memory, 3D NAND, and CMOS image sensor wafers, all of which require stable chamber conditioning after wet maintenance to prevent particle excursions and metal cross-contamination.
| Downstream application | C3F8 addition ratio by volume | Pressure / power setpoint | Critical control | Terminal device type |
|---|---|---|---|---|
| PECVD chamber cleaning | 25–40% | 2.5–4.0 Torr; RPS 5.5–8.0 kW | OES endpoint at 703.7 nm | Logic, DRAM, 3D NAND, CMOS image sensors |
| Silicon nitride hard mask etch | 6–14% | 25–60 mTorr; CCP bias 80–250 W | Pad oxide loss, sidewall polymer thickness | FinFET, DRAM buried wordline, 3D NAND staircase |
| High-aspect-ratio dielectric contact etch | 12–22% | 20–60 mTorr; dual-frequency CCP | CF2/F ratio, ARDE, etch stop | DRAM capacitor contacts, 3D NAND contact plugs, CMOS image sensor deep trench isolation |
| Porous low-k dielectric patterning | 15–35% | 10–40 mTorr; ICP/CCP hybrid | κ ≤ 2.5, polymer closure threshold | Low-power logic SoC, network processors, AI accelerators, mobile application processors |
| Wide-bandgap dielectric hard mask opening | 8–16% | 5–20 mTorr; ICP 800–1,500 W | Carbon residue, TDDB, post-etch XPS | SiC MOSFET, GaN HEMT, electric vehicle power modules |
In gate spacer and shallow trench isolation liner etching, perfluoropropane C3F8 Electronic/EL Grade is introduced into CH3F/O2/Ar chemistry as a CF2-supplying polymer precursor. The C3F8 addition ratio is held between 6% and 14% by volume, with CH3F at 30–45 vol%, O2 at 8–14 vol%, and argon balance, in a dual-frequency capacitively coupled plasma source operating at 25–60 mTorr; the low-frequency bias is controlled between 80 W and 250 W to limit pad oxide loss. The process boundary exists because C3F8 fractions below 8% reduce sidewall fluorocarbon film thickness below the threshold needed for anisotropic SiN etch, while fractions above 14% produce polymer clogging at the feature opening and reactive ion etching lag. Compliance constraints for this operation derive from SEMI C3.57 metal impurity ceilings because cation residues from fluorocarbon plasma can shift transistor threshold voltage in high-K metal gate stacks. The downstream process includes pad oxidation at 800–1,000 °C, silicon nitride deposition by low-pressure chemical vapor deposition, lithographic patterning, resist trimming, and etching of the SiN layer with continuous in-situ monitoring by optical emission spectroscopy and quadrupole mass spectrometry. Terminal finished product types are FinFET and gate-all-around logic transistors, DRAM buried wordline structures, and 3D NAND staircase hard masks, where nitride loss uniformity across 300 mm wafers is the release criterion, not average etch rate alone.
Contact etch for DRAM buried cell capacitors and 3D NAND contact plugs imposes a different C3F8 ratio window than chamber cleaning because the fluorocarbon film must deposit on oxide sidewalls while the bottom SiN etch stop remains closed. The C3F8 Electronic/EL Grade blending ratio is set between 12% and 22% by volume, with CF4 at 4–10 vol%, O2 at 4–8 vol%, and Ar at 55–75 vol%, at source pressure 20–60 mTorr and dual-frequency plasma excitation with source frequency 40 MHz and bias 13.56 MHz or lower. The compliance anchor remains SEMI C3.57 for perfluoropropane purity, but PFC emission control is additionally governed by SEMI S23 because the high-flow etch consumes more C3F8 per wafer than a clean step and requires combustion or plasma abatement of CF4 and residual C3F8. In the production sequence, borophosphosilicate glass or phosphosilicate glass is deposited by sub-atmospheric CVD, annealed, densified, and patterned with deep-ultraviolet lithography; the plasma etch then transfers contact holes with aspect ratios from 10:1 to 25:1 through the dielectric to the silicon or polysilicon landing pad. The dominant failure modes are aspect-ratio dependent etch stop, sidewall bowing, and profile twisting when the CF2/F ratio drifts across the wafer edge. Terminal device types include DRAM with buried cell array transistors, 3D NAND contact plugs, and CMOS image sensor deep trench isolation, all of which require mid-etch partial pressure control of C3F8 rather than total flow control alone.
The use of perfluoropropane C3F8 Electronic/EL Grade in porous organosilicate low-k dielectric patterning is constrained by a process cliff-edge at approximately 35% C3F8 partial pressure. The allowable addition ratio for trench and via patterning in a 45 nm-node and below back-end-of-line stack is 15–35 vol% C3F8 in a CF4/N2/Ar plasma at 10–40 mTorr; operation above the 35% threshold causes rapid fluorocarbon polymer deposition on the etch mask and trench sidewall, reducing critical dimension opening and forcing process aborts. The compliance and contamination boundary is defined by SEMI C3.57 for the gas itself, while waste stream limits are aligned to SEMI S23 PFC decomposition efficiency. The C3F8 molecule has a 100-year GWP of 8,830, so the etch tool must be integrated with a PFC abatement device with destruction removal efficiency above 95%. In the downstream process, a porous low-k film with dielectric constant κ ≤ 2.5 is deposited by PECVD, capped with silicon oxide, patterned by 193 nm immersion lithography, and etched in an ICP/CCP hybrid reactor with wafer temperature controlled below 60 °C to limit plasma-induced damage and pore collapse. After etch, the photoresist is stripped in reducing or oxidizing ash, and the via/trench profile is preserved for subsequent barrier-seed deposition and copper electroplating. Published data for C3F8 in porous ultra-low-k integration is limited relative to C4F8/CF4 chemistry; process engineers should validate sidewall polymer composition by X-ray photoelectron spectroscopy on actual device stacks before locking the etch recipe. Terminal products include low-power logic system-on-chip devices, network processors, artificial intelligence accelerators, and mobile application processors, all of which require low-k damage control because a small increase in effective dielectric constant can negate the speed gain from the patterned feature geometry.
Wide-bandgap power semiconductor fabrication applies perfluoropropane C3F8 Electronic/EL Grade in the opening of silicon dioxide hard masks on 4H-SiC and GaN-on-SiC epitaxial wafers before high-temperature implant activation or trench gate formation. The gas blending ratio is lower than front-end dielectric etch, typically 8–16 vol% C3F8 in Ar/O2, at chamber pressure 5–20 mTorr, inductively coupled plasma source power 800–1,500 W, and platen bias voltage 100–400 V. The low C3F8 fraction is selected to minimize carbon residue and fluorine-related electrical damage on the SiC or GaN surface. Compliance for this segment starts with SEMI C3.57 assay and trace moisture/metals control, and is supplemented by ISO 14644-1:2015 Class 5 or better gas handling room requirements because wide-bandgap gate oxide reliability is measured in leakage current and time-dependent dielectric breakdown according to JEDEC test protocols. The production sequence includes PECVD deposition of a 1.0–2.0 µm silicon dioxide mask, photoresist patterning, hard mask etch, post-etch residue removal by wet or plasma treatment, and then high-temperature ion implantation or trench etch for vertical MOSFET structures. Published data for C3F8 in GaN p-type gate recess configurations is limited; direct substitution from silicon oxide etch without XPS surface carbon measurement and contact resistance verification is not recommended. Terminal product types are 650 V and 1,200 V silicon carbide metal–oxide–semiconductor field-effect transistors, GaN high electron mobility transistors for fast chargers, and power modules in electric vehicle traction inverters.
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Perfluoropropane, C3F8 (CAS 76-19-7, molar mass 188.02 g/mol, boiling point -36.7 °C at 1 atm), is supplied as a liquefied compressed gas under the designation Electronic/EL Grade where the material is filled, stored, and delivered with impurity limits matched to semiconductor manufacturing requirements. The grade is defined not by a single universal specification but by a certificate of analysis profile that typically lists a minimum volumetric purity of 99.999% (5N) or 99.9995% (5.5N) depending on package configuration. Model strings applied by gas suppliers commonly encode purity and package size—for example C3F8-5.5N-EL-450L—although naming is not standardized across vendors and must be checked against the CoA.
Electronic/EL Grade material is distinguished from refrigerant-grade R-218 by three control attributes: gas-phase moisture below 1 ppmv, total metal residue below 10 ppb w/w in selected elements, and sub-micrometer particle counts compatible with ISO 14644-1:2015 Class 2 intake environments. The product is maintained in electropolished 316L stainless steel cylinders or ISO containers fitted with high-integrity valves to minimize atmospheric ingress. At 25 °C, the vapor pressure is approximately 792 kPa, which permits liquid-phase withdrawal through a dip tube or gas-phase withdrawal through head-space connection. The liquid density at saturation pressure and 20 °C is approximately 1.58 g/cm³, and this value enters fill-ratio calculations under pressure vessel codes such as ISO 11114-1:2020 and national transport regulations.
In low-pressure plasma etching of silicon dioxide, the gas-phase fluorine-to-carbon ratio is a first-order variable because it sets the relative densities of atomic fluorine and fluorocarbon radicals. CF4 carries an F:C ratio of 4, yielding a halogen-rich discharge that etches SiO2 rapidly but also attacks silicon with significant isotropic undercut. C3F8 carries an F:C ratio of 2.67 and consequently shifts the radical population toward CF2 and CF3, which adsorb on the wafer surface and form a thin fluorocarbon passivation layer. That layer suppresses silicon and photoresist etch while fluorine continues to volatilize silicon dioxide as SiF4. The process window, however, is narrow: excessive polymer accumulation reduces oxide etch rate and can trigger etch stop in high-aspect-ratio contacts, while insufficient polymerization reverts selectivity toward CF4-like behavior. In production equipment, this trade-off is managed by co-feeding O2 at controlled flow ratios, typically in the range 10% to 30% of the C3F8 flow, to oxidize surface carbon and preserve a steady-state polymer thickness. Published data for specific gas ratios in advanced-node stacks remains limited because chamber wall conditions and bias power dominate the surface reaction balance.
Remote plasma chamber cleaning of PECVD reactors represents the highest-volume use of Electronic/EL Grade C3F8. In this application, the compound is fed into a remote plasma source, typically operating between 2.45 GHz and 13.56 MHz, where electron-impact dissociation generates F, CF, CF2, and CF3 species. These radicals convert silicon nitride and silicon oxide residues to SiF4, CO, and CO2 before the gases are pumped through the abatement train. Compared with C2F6, which supplies six fluorine atoms per molecule, C3F8 supplies eight fluorine atoms per molecule and therefore can reduce the required gas flow for a fixed fluorine delivery. This does not guarantee lower emissions in all installations; the actual utilization efficiency depends on source power density, chamber temperature, and throttle-valve position. In a production-scale PECVD line, the practical clean endpoint is determined by optical emission spectroscopy of the SiF4 emission line rather than a fixed time. Where C2F6 is being replaced by C3F8, the gas panel must be re-evaluated because C3F8 has a lower vapor pressure than C2F6 and may require auxiliary heat input on the cylinder jacket to sustain mass-flow-controller inlet pressure in cold sub-fab locations.
Electronic/EL Grade C3F8 specifications are governed less by total purity than by the trace constituents that affect gate oxide integrity, contact resistance, and particle defects. For a representative 5N grade, supplier certificate values often include maximum H2O of 1 ppmv, O2 of 1 ppmv, N2 of 5 ppmv, total hydrocarbons below 1 ppmv, and CF4 or C2F6 homologues below 50 ppmv. These ceilings are not universal; they shift with equipment maker requirements and device generation. Moisture is measured at point-of-use by cavity ring-down spectroscopy, while permanent gases are determined by gas chromatography with pulsed-discharge detection. Metallic impurities are captured by impinger sampling and analyzed by inductively coupled plasma mass spectrometry, with action limits commonly set at 10 ppb w/w for the sum of Fe, Cr, Ni, Al, Cu, and Na. Distribution systems use electropolished 316L stainless steel tubing, metal-seated regulators, and continuous purge lines to avoid dead legs. Any replacement of elastomeric seals with perfluoroelastomer components must be validated for particle shedding and off-gassing, because seal degradation is a more frequent cause of point-of-use contamination than cylinder content drift.
C4F8 is often selected for high-aspect-ratio oxide etching because its F:C ratio of 2 supports thicker sidewall polymer and blocks lateral attack in features with depth-to-width ratios exceeding 10:1. That same polymer thickness becomes a limitation when the feature aspect ratio is moderate or the mask opening is large, because the polymer can close the via and reduce the oxide etch rate. In such cases, Electronic/EL Grade C3F8 is substituted to obtain an intermediate F:C ratio of 2.67, producing a thinner but still sufficient passivation layer. The trade-off is process-window sensitive: at low bias power the C3F8-based plasma may display higher fluorocarbon deposition on the sidewall relative to CF4, while at high bias power the polymer is removed too rapidly and silicon selectivity falls. Wafer-to-wafer repeatability in a dual-frequency capacitively coupled plasma chamber therefore requires closed-loop control of the RF power ratio between the 60 MHz source and 2 MHz bias generators. Published sidewall-angle data for specific C3F8/O2/Ar mixtures in sub-100 nm contacts is limited in open literature because most advanced-node etch chemistries are not disclosed at formulation level.
A comparison of molecular properties relevant to etch and clean gas selection is shown in Table 1. The values are compiled from public NIST fluid property data and standard gas-handling documents; they are not supplier-specific and should be used for relative ranking rather than equipment calibration.
| Property | CF4 | C2F6 | C3F8 | c-C4F8 |
|---|---|---|---|---|
| Molar mass (g/mol) | 88.00 | 138.01 | 188.02 | 200.03 |
| Boiling point (°C) | -128.1 | -78.2 | -36.7 | -6.0 |
| F:C atomic ratio | 4 | 3 | 2.67 | 2 |
| Fluorine atoms per molecule | 4 | 6 | 8 | 8 |
| Polymerizing tendency in oxide etch | Low | Moderate | Moderate-high | High |
Beyond molecular properties, Electronic/EL Grade C3F8 differs from refrigerant-grade R-218 primarily in analytical burden. Table 2 lists representative impurity ceilings published in a semiconductor gas supply specification. These values are not to be read as universal limits; a given device manufacturer may impose stricter controls for specific elements, particularly Na and Fe, after front-end-of-line integration testing.
| Parameter | Typical Electronic/EL Grade ceiling | Analytical technique | Reference standard |
|---|---|---|---|
| Purity | 99.999% min | GC-PDD | SEMI C3 |
| H2O | 1 ppmv | CRDS | SEMI C3 |
| O2 | 1 ppmv | GC-PDD | SEMI C3 |
| N2 | 5 ppmv | GC-PDD | SEMI C3 |
| Total hydrocarbons | 1 ppmv | GC-FID | SEMI C3 |
| Metals (Fe+Cr+Ni+Al+Cu+Na) | 10 ppb w/w | ICP-MS | Supplier CoA |
| Particles ≥ 0.1 µm | 0.1 count/L | LPC | ISO 14644-1:2015 |
Storage and handling of Electronic/EL Grade C3F8 are governed by the same pressure vessel regulations that apply to liquefied fluorinated gases. The cylinder fill ratio must not exceed the mass of liquid that would occupy the full water capacity at 55 °C, as required by transport codes and ISO 11114-1:2020 material compatibility assessments. During high-flow chamber clean or etch processes, Joule-Thomson cooling from liquid withdrawal can chill the cylinder neck and reduce head-space pressure below the mass-flow-controller minimum inlet pressure. The usual corrective measure is an external cylinder heater or a low-pressure vaporizer, not an increase in fill ratio. Because C3F8 is chemically stable at ambient temperature, the principal occupational hazard arises from oxygen displacement and from decomposition products if the gas is exposed to flames or heated metal surfaces above roughly 500 °C. Decomposition can produce HF, COF2, and fluorinated olefins; exhaust abatement and gas detection are therefore specified under facility safety codes rather than by the gas CoA. Published data for decomposition kinetics in semiconductor abatement units is limited; vendor-specific abatement validation is required before changing from C2F6 to C3F8.
NF3 continues to displace perfluorocarbon clean gases in some high-throughput PECVD lines because its dissociation is fast in remote plasma sources and its abatement is less fuel-intensive. Electronic/EL Grade C3F8 remains specified where NF3 molybdenum-catalyst by-products or particle excursions create tool qualification failures. In these lines, the gas cabinet must accommodate a higher cylinder count because the mass of fluorine delivered per kilogram is lower for C3F8 than for NF3; this raises logistics but reduces the local inventory of reactive fluorine. A direct substitution from NF3 to C3F8 is not a drop-in change. The remote plasma source must be reconfigured for the lower dissociation cross-section of C3F8, and the abatement unit must be revalidated for COF2 and residual perfluorocarbon destruction efficiency. Where a new abatement catalyst is introduced, the tool owner must confirm that destruction of C3F8 at the specified flow rate does not exceed particulate emission limits or acid-gas scrubbing capacity. Published data for destruction efficiencies in different abatement types is limited to supplier validation reports; no single removal efficiency can be assumed across all tool configurations.
