| HS Code | 122289 |
| Product Name | High-Temperature Stripper Electronic/EL Grade |
| Appearance | Clear colorless to pale yellow liquid |
| Chemical Type | Alkanolamine-based organic stripper |
| Active Ingredients | Amine compounds, polar solvents, corrosion inhibitors |
| Purity Grade | Electronic/EL grade (semiconductor process grade) |
| Metal Ion Content | ≤ 1 ppm (individual metals, typically ppb level) |
| Specific Gravity 20c | 1.05 - 1.25 |
| Ph 10percent Aqueous Solution | 10.0 - 12.5 |
| Viscosity 25c | 5 - 20 cP |
| Flash Point | > 100°C (closed cup) |
| Boiling Point Range | 150°C - 250°C |
| Solubility In Water | Fully miscible |
| Thermal Stability | Stable up to 200°C; no decomposition below 150°C |
| Etch Rate Selectivity | High selectivity to SiO2, Si3N4, and metal films |
| Stripping Performance | Removes cured/ashed photoresist at high temperature |
| Operating Temperature Range | 80°C - 180°C |
| Storage Life | 12 months from date of manufacture in sealed original container |
| Packaging Type | HDPE drum with nitrogen purging |
| Safety Hazard | Alkaline, corrosive; causes eye and skin irritation |
As an accredited High-Temperature Stripper Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | High-Temperature Stripper Electronic/EL Grade, 5 gallons per pail, packaged in a sealed HDPE container for purity, stability, and safe handling. |
| Container Loading (20′ FCL) | 20′ FCL: Electronic-grade stripper loaded in sealed 20-foot container, drums properly secured and segregated, no compatibility issues. |
| Shipping | Shipments of High-Temperature Stripper Electronic/EL Grade require specialized hazardous-material packaging and labeling. Transport in sealed, corrosion-resistant containers to prevent leaks. Ensure compliance with local and international chemical shipping regulations. Temperature stability is essential; avoid extremes. Proper documentation and handling training are mandatory. Delivery is via certified carriers experienced with electronic-grade chemicals. |
| Storage | Store in a tightly sealed, labeled original container in a cool, dry, well-ventilated area, protected from sunlight, heat, and moisture. Keep away from strong oxidizers, acids, and reactive metals. Use corrosion-resistant secondary containment, inspect containers regularly for leaks or damage, and control access to maintain electronic/EL-grade purity. |
| Shelf Life | Shelf life is typically 12 months when stored sealed in original container at controlled temperature, away from moisture and contaminants. |
After dielectric etch and O2/CF4 plasma ashing in dual-damascene Cu/low-k integration, fluorinated polymer residue, copper oxide/hydroxide film, and damaged low-k debris remain on via walls and trench floors. An EL-grade high-temperature stripper is fed undiluted through a 0.05 µm point-of-use PTFE filter into a 300 mm single-wafer spray processor. The platen temperature is held at 65–85 °C. The stripper acts by nucleophilic attack on C–F bridges and by chelation of Cu(I)/Cu(II) centers. Corrosion inhibitors maintain copper etch rate below 0.5 nm/min at 80 °C on electroplated copper. Barrier metals such as TaN and Co are not measurably attacked in visual and XPS endpoint audits. Dwell time in the spray chamber is 45–120 s. After chemical dispense, the wafer receives ultrapure DI water rinsing at ≤10 ppb total organic carbon as defined in ASTM D1193-06(2018). Drying follows under heated N2 at 0.8–1.5 bar.
Liquid-phase impurity control for the BEOL-compatible grade is tighter than for standard electronic solvents. The release limits used on production drum lots are summarized below.
| Analyte | Control limit | Reference method |
|---|---|---|
| Chloride (Cl⁻) | ≤10 ppb | ASTM D512-23 |
| Sulfate (SO₄²⁻) | ≤10 ppb | ISO 10304-1:2020 |
| Sodium (Na) | ≤5 ppb | ISO 17294-2:2023 |
| Potassium (K) | ≤5 ppb | ISO 17294-2:2023 |
| Iron (Fe) | ≤10 ppb | ISO 17294-2:2023 |
| Total trace metals | ≤50 ppb | ISO 11885:2023 |
The main production bottleneck is residue penetration in high-aspect-ratio vias above 10:1. Single-wafer spray alone may leave fluoropolymer at the trench bottom. Megasonic assist at 0.5–1.0 W/cm² and 950 kHz is added in some modules to reduce the diffusion boundary layer. Bath temperature must remain inside the 65–85 °C window. Below 65 °C, lift-off is incomplete and defect density rises. Above 85 °C, certain organosilicate low-k films show surface roughness increase greater than 0.5 nm. Recirculating batch immersion is limited by copper loading. Copper concentration must not exceed 500 ppb as measured by ISO 17294-2:2023; above this ceiling, the protectant is depleted and the copper surface becomes susceptible to pitting. Low-k film thickness change after 2 h at 80 °C is held at ≤0.5 nm for k values of 2.4–2.7. Terminal products include logic SoCs, ASICs, AI accelerators, CMOS image sensors, and automotive microcontrollers.
Wafer-level bumping constructs Cu pillar and Sn-Ag cap structures directly on a polyimide or polybenzoxazole dielectric. The plating mask is a diazonaphthoquinone-novolak positive photoresist with thickness from 40 µm to 120 µm. After copper electroplating, the resist is cross-linked by the plating electrolyte and by thermal excursions. The EL-grade high-temperature stripper removes the thick film without attacking the Sn-Ag cap or the underlying Cu pillar. Galvanic corrosion between Cu and Sn-Ag during the aqueous rinse step is controlled by holding chloride and sulfate each below 10 ppb. The formulation has water content at or below 1 wt%. The undiluted bath is heated to 70–90 °C in a batch spray processor. Fan-nozzle flow rates of 5–15 L/min per chamber provide mechanical shear that assists film lift-off. Process intervals of 5–15 min are common for 40–80 µm films. For 100–120 µm films, the bath is operated at 85–95 °C with a second pass or extended dwell.
Temperature control is a process conflict. At ≤70 °C, the thick plating resist lifts slowly and flakes can redeposit on the wafer backside. At ≥95 °C, dissolution of the silver component in the Sn-Ag cap begins to shift cap composition. The production window is therefore maintained at 80±5 °C on many bumping lines. Exhaust volumetric flow in the process module is kept at 8–15 m³/min to keep vapor concentration below the lower flammability limit of the solvent blend. The bath is filtered through 0.1 µm PTFE membranes and replaced every 100–150 wafers for 100 µm dry film, because resist solids loading raises viscosity and reduces spray uniformity. The stripped wafer is rinsed with DI water having ≤5 ppb chloride per ASTM D512-23. N2 drying follows at 0.6–1.2 bar. The stripper does not contain halogenated hydrocarbons that would trigger RoHS restrictions in the final packaging material. End products include wafer-level chip-scale packages, fan-out wafer-level packages, and 2.5D interposers with microbump pitches down to 40 µm.
Array rework in oxide TFT backplane fabrication removes photoresist from molybdenum/aluminum gate stacks without allowing molybdenum to corrode. The EL-grade stripper is applied in a conveyorized horizontal spray tool with glass substrate temperatures of 50–70 °C. High-temperature operation shortens rework time for 1.5–3.0 µm organic photoresist layers to 90–180 s. The stripper must not lift passivation layers or create pinholes in the organic planarization layer. Bath make-up is undiluted and recirculated through 0.1 µm filters. Sodium and potassium levels in the drum are held below 10 ppb because mobile alkali ions shift thin-film transistor threshold voltage. Stripped panels are rinsed with 18.2 MΩ·cm DI water at 25 °C. An air knife removes water droplets before the glass exits the process module.
Metal compatibility in this segment covers molybdenum, titanium, aluminum, ITO, and copper data lines protected by an azole inhibitor. Bath replacement is triggered when total organic carbon exceeds 50,000 ppm or when chloride pickup from rinse cross-contamination exceeds 100 ppb. Terminal applications include AMOLED pixel definition layers, TFT-LCD array line rework, and flexible display backplanes on polyimide.
A quartz immersion tank with N2 sparging at 1.0–2.0 L/min removes hardened electron-beam and optical resists after SiNx passivation etching in GaN-on-SiC power amplifier fabrication. The stripper is heated to 80–110 °C. In this range, lift-off bilayer resists based on PMMA and a novolak top layer dissolve without leaving carbonaceous residue on AuGe/Ni/Au or Ti/Al/Ni/Au ohmic contacts. The tank components are quartz and PTFE only. Stainless steel is excluded because metal ions plate onto the AlGaN barrier and shift sheet carrier concentration.
Ionic impurity ceilings are stricter than in silicon logic. Sodium, potassium, and calcium are each held below 5 ppb. Iron, copper, and nickel are held below 5 ppb. These concentrations are verified on the drum by ISO 17294-2:2023 before release. Immersion time is 10–30 min, depending on resist thickness and plasma hardening dose. Endpoint is confirmed optically by metal aperture inspection. After stripping, the wafer is immersed in an IPA rinse bath at 25–40 °C and dried with filtered N2. The process is used for gate-L of 0.15–0.25 µm GaN HEMT devices and for source/drain metal lift-off in millimeter-wave MMICs. Terminal products include 5G base station power amplifiers, satellite communication front-ends, and X-band radar MMICs.
ABF substrate etch lines routinely strip 100–120 µm dry-film resist over semi-cured epoxy build-up film. The dry film is acrylate-based; the underlying ABF is an epoxy/phenolic network with silica filler. A high-temperature EL-grade stripper formulated with low water content at ≤1 wt% swells the dry film but leaves the ABF film dimensionally stable. In horizontal flood spray modules, panel surface temperature is maintained at 60–80 °C. Spray pressure of 1.0–2.5 bar is used with a residence time of 2–6 min. The stripper does not contain chlorinated solvents, thereby avoiding chloride residues that can initiate copper migration in subsequent highly accelerated temperature and humidity stress tests.
Published data for ABF weight gain after 6 min at 80 °C in this specific EL-grade formulation is limited. Swelling must be verified on split lots by cross-sectional SEM and surface profilometry. The process is followed by DI water rinsing at ≤10 ppb chloride per ASTM D512-23. Terminal products include flip-chip ball grid array substrates, chiplet modules, and system-in-package carriers.
After Bosch DRIE leaves fluoropolymer sidewall deposits on a 30–80 µm silicon device layer, the photoresist mask is no longer removable in conventional solvent baths. Plasma hardening cross-links the top surface of the resist. The EL-grade high-temperature stripper is used in a quartz immersion bath at 100–130 °C. Megasonic energy at 400–950 kHz is applied at low acoustic intensity to accelerate film lift-off without damaging released microstructures. Sodium and potassium are held below 5 ppb to keep mobile-ion contamination in SiO2 and SiNx insulating surfaces below the level that shifts comb-drive actuation voltage. Process time is 30–60 min for 10–50 µm thick photoresist masks hardened by high-density plasma.
The wafer is rinsed in DI water at 25 °C for 10–15 min with surface resistivity monitored to 18.2 MΩ·cm. Drying uses low-speed spin in heated N2. Terminal products include inertial measurement units, silicon microphones, pressure sensors, and micro-mirror arrays.
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The High-Temperature Stripper Electronic/EL Grade, designated in supplier documentation as EL-HT-04, is a non-aqueous solvent formulation for immersion and single-wafer spray removal of positive-tone DUV photoresist, ion-implant-hardened crust, and fluorinated post-etch residues on silicon, silicon dioxide, silicon nitride, and Cu/low-k interconnect structures. The product is composed of a high-boiling polar aprotic solvent blend, an alkanolamine activator at 8–12 wt%, and a non-ionic corrosion inhibitor package. The electronic/EL grade is distinguished from technical-grade strippers by certification to trace metal concentrations at or below 10 ppb for critical mobile ions, particle loading below 80 particles/mL at ≥0.2 μm, and absence of N-methyl-2-pyrrolidone tested by GC-MS. Application temperature is maintained at 105–120 °C; the product is filtered through 0.05 μm point-of-use membranes before dispense. Rinse is direct deionized water without intermediate solvent rinsing.
Incoming quality assurance uses the certificate-of-analysis limits listed in Table 1. Each lot is supplied with batch-specific results generated after nitrogen sparging and 0.05 μm fluoropolymer filtration. The methods are selected for compatibility with polar aprotic solvent matrices; Karl Fischer titration is performed on a coulometric system to avoid volumetric reagent drift at water levels below 0.5% w/w.
| Parameter | Limit | Method |
|---|---|---|
| Appearance | Clear, no visible haze | Visual inspection |
| Water content | ≤0.5% w/w | ASTM E203 |
| Density at 20 °C | 1.04–1.08 g/cm³ | ASTM D4052 |
| Kinematic viscosity at 25 °C | 6.0–12.0 mm²/s | ASTM D7042 |
| Flash point, closed cup | ≥96 °C | ASTM D93 |
| Trace metals Na, K, Fe, Cu, Zn, Cr, Ni, Al | ≤10 ppb each | SEMI C43 + ICP-MS |
| Chloride | ≤0.5 ppm | Ion chromatography after 1:10 aqueous extraction |
| Particles ≥0.2 μm | ≤80 particles/mL | SEMI C55 |
| N-methyl-2-pyrrolidone content | <0.1 wt% | GC-MS |
| Sulfate | ≤1.0 ppm | Ion chromatography |
| pH of 1:10 aqueous dilution at 25 °C | 10.2–10.8 | Potentiometric |
On a production-scale 300 mm wet bench configured with a 40 L quartz bath, the stripper is recirculated through a 0.05 μm UPE filter at 8–12 tank volumes per hour. Bath temperature is controlled by a dual-loop heat exchanger with setpoint tolerance of ±2 °C; excursions above 120 °C trigger automatic heater lockout. In single-wafer spray tools, the dispense sequence is 60–90 s at 110 °C with wafer rotation at 800–1,200 rpm, followed by 25 °C ultrapure water rinse at 1.5 L/min for 60 s. Low-k hydrophobic surfaces require an additional isopropanol vapor dry step to prevent water ingress into porous SiCOH films.
Bath life is terminated when water content exceeds 0.8% w/w or total Na, K, and Fe concentration exceeds 50 ppb, whichever occurs first. FTIR monitoring of the carbonyl band at 1685 cm⁻¹ and the N–H deformation band at 1590 cm⁻¹ tracks activator depletion; a 15% reduction in integrated peak area is the replacement threshold. Batch-to-batch variation on one production line was ±0.3 wt% for activator content over 14 lots, which produced no measured shift in photoresist removal rate outside the ±5% fab control limit.
Typical use cases include front-end post-etch residue removal after gate stack reactive ion etch and back-end via/trench cleaning after dual Damascene etch. The product removes photoresist hardened by arsenic or boron implantation at doses up to 1×1016 ions/cm² without a plasma descum step. In one 200 mm production line, integrating the stripper into the implant strip module reduced queue time between implant and clean from 4 h to 45 min because the hardened crust dissolved at 110 °C without additional downstream ashing.
The process window is bounded by the tradeoff between residue solubility and copper surface loss. At 110 °C, a 350 °C ion-implant-hardened positive resist film shows a removal rate of 2.4–3.1 μm/min after 60 s immersion, measured by film thickness interferometry. The same fluid at 115 °C produces blanket electroplated copper loss of <1 Å/min, converted from four-point probe sheet resistance. At 125 °C, copper loss rises to 3–5 Å/min; therefore the upper control limit is set at 120 °C. The lower limit of 105 °C is set by incomplete removal of fluorinated residue from CHF₃/CF₄ etch processes; residue levels on 45 nm half-pitch trenches remain above the detection threshold at 100 °C after 90 s.
Aluminum bond pad exposure imposes an additional constraint. The non-ionic corrosion inhibitor must remain above 1.0 wt% in the working bath. Below this threshold, potentiostatic screening shows localized corrosion rates exceeding 15 nm/min at pH 10.5–11.0. The pH is therefore maintained between 10.2 and 10.8; below 10.2 residue removal decreases, and above 10.8 copper oxide growth accelerates. Rinse must begin within 15 s after stripper dispense ends. Delayed rinse permits solvent evaporation and redeposition of dissolved organic residues on sidewalls.
The product is compatible with electrochemically deposited copper, physical vapor deposited tantalum nitride, titanium nitride, silicon carbide etch stop, and dense low-k SiCOH dielectrics under the stated temperature and time limits. Porous low-k dielectrics with porosity above 25% require post-strip vacuum bake at 150 °C for 2 h to restore dielectric constant; published data for this specific configuration is limited, and on-wafer k-value verification by mercury probe is used before lot acceptance.
Table 2 summarizes the distinction between the electronic/EL high-temperature grade and conventional stripper classes. The comparison values are supplier qualification data for comparison lots and are not universal properties of all formulations in each class.
| Stripper class | Typical operating temperature | Copper etch at 110 °C | Trace metals | Hardened DUV crust removal | Rinse compatibility |
|---|---|---|---|---|---|
| Electronic/EL high-temperature | 105–120 °C | <1 Å/min | ≤10 ppb | High | Direct DI water |
| NMP-based | 80–100 °C | <1 Å/min | ≤100 ppb | Moderate | Solvent pre-rinse required |
| Hydroxylamine/amine-based | 60–90 °C | 5–30 Å/min at 90 °C | Variable | High | DI water, corrosion risk |
| Semi-aqueous | 70–90 °C | <1 Å/min | Variable | Moderate | Intermediate organic rinse |
The primary difference is the combination of high-temperature operation at 105–120 °C with electronic-grade purity. Conventional solvent strippers certified to technical grade may contain metal contamination up to 500 ppb and particle concentrations above 1,000 particles/mL, which are incompatible with mobile ion control in sub-28 nm device fabrication. NMP-based formulations are restricted under REACH Annex XVII entry 71 and often require solvent pre-rinse before DI water. Hydroxylamine- or amine-based formulations can etch copper at elevated temperature, and semi-aqueous blends usually operate below 90 °C, leaving fluorinated crust residue on high-dose ion implant resists.
Exposed cobalt, ruthenium, or molybdenum liner materials require separate compatibility screening because the corrosion inhibitor package was optimized for copper and aluminum. Published data for this specific configuration is limited. A 60 s immersion at 110 °C with thickness change measured by X-ray fluorescence or four-point probe is used before release to production. The product contains no fluoride or chloride; however, water ingress hydrolyzes the solvent blend and generates acidic degradation products. At water above 0.8% w/w, the pH of a 1:10 aqueous dilution falls below 10.0, and copper etch increases to >2 Å/min in production wet bench monitoring. Karl Fischer titration every 4 h during continuous operation is therefore mandatory.
Flash point closed cup is 96 °C by ASTM D93. Vapour pressure at 110 °C is 0.8 kPa. Local exhaust ventilation with a face velocity of 0.5 m/s is required at the wet bench because the product is heated above its flash point under normal use. The liquid is corrosive to skin and eyes; the amine component has an occupational exposure limit of 1 ppm 8-hour time-weighted average. Storage is under nitrogen blanket at 10–25 °C; below 5 °C, partial crystallization may occur and requires slow agitation at 25 °C for 12 h before use. Waste streams must not be mixed with strong mineral acids because exothermic neutralization may generate localized boiling.
