| HS Code | 962584 |
| Product Name | Electronic/EL Grade Stripper (Compound Process) |
| Physical State | Liquid |
| Appearance | Clear colorless to pale yellow liquid |
| Chemical Family | Organic amine-based stripper formulation |
| Purity Assay | 99.9% minimum |
| Active Content | 90–100 wt% |
| Water Content | ≤500 ppm by weight |
| Metal Impurities | Na, Fe, Cu, Zn each ≤10 ppb; Total ≤50 ppb |
| Density At 20 C | 0.98–1.05 g/cm³ |
| Boiling Point | ≥150°C |
| Flash Point | ≥80°C |
| Viscosity At 25 C | 1.5–5.0 cP |
| Ph 10 Aqueous Solution | 10.5–12.5 |
| Solubility In Water | Miscible |
| Filtration Rating | ≤0.1 µm |
As an accredited Stripper (Compound process) Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 4 L clean-room-grade HDPE bottles, double-bagged and nitrogen-blanketed, with tamper-evident seals and traceable EL-grade labeling. |
| Container Loading (20′ FCL) | 20′ FCL: palletized drums/IBCs of EL-grade electronic stripper, securely braced, segregated, hazard-compliant, protected from moisture and contamination. |
| Shipping | This electronic-grade stripping compound is shipped in sealed, corrosion-resistant containers to preserve purity and prevent contamination. Transport follows hazardous materials regulations, requiring proper labeling, documentation, and secure upright positioning. Handle away from moisture, heat, and incompatible substances. Ventilated storage and protective measures during loading/unloading are essential to ensure safe delivery and product integrity. |
| Storage | Store in a clean, tightly sealed original container in a cool, dry, well-ventilated area, ideally between 15–30°C. Protect from moisture, direct sunlight, and physical damage. Keep away from oxidizers, acids, and ignition sources. Use dedicated, contamination-free dispensing equipment to maintain Electronic/EL Grade purity. Ensure secondary containment and proper labeling. |
| Shelf Life | Shelf life is typically 12 months from manufacture date when stored sealed in original container at room temperature. |
In front-end semiconductor wafer rework, electronic-grade stripper concentrates are used after plasma ashing to remove implanted crust from 193 nm and 248 nm photoresist. The bath is a solvent-amine formulation containing hydroxylamine, 2-aminoethanol or an N-methyl-2-pyrrolidone replacement solvent, catechol inhibitor, and ultrapure water. In 300 mm wafer fabs, immersion batch tools with quartz or polyvinylidene fluoride wetted surfaces operate at 70 °C to 85 °C. A recirculation loop passes the stripper through a 0.1 µm polytetrafluoroethylene filter at 40 L/min to control particle counts below 50 counts/mL at 0.2 µm. Megasonic transducers operate at 800 kHz to 1 MHz to delaminate carbonized resist from contact and via corners. The product is used neat; for resist film shells below 0.8 µm, a 1:1 volumetric dilution with ultrapure water is used. Incoming liquid metal impurities are controlled by inductively coupled plasma mass spectrometry per ASTM D5673-16; acceptance for lithium, sodium, magnesium, potassium, calcium, chromium, iron, nickel, copper, zinc, and lead is ≤ 10 µg/L per element. Chloride and sulfate are measured by suppressed ion chromatography per ASTM D4327-17 with limits of 200 µg/L and 300 µg/L, respectively. Bath life is governed by Karl Fischer water monitoring per ASTM E203; dissolved resist loading is held below 4 g/L by bleed-and-feed replenishment. Because N-methyl-2-pyrrolidone is restricted under EU REACH Annex XVII entry 71, the solvent fraction is typically shifted to N-ethyl-2-pyrrolidone or N-butylpyrrolidone. End wafers are logic and memory substrates with aluminum-copper or copper backend-of-line stacks, with post-strip equivalent oxide thickness drift below 0.3 Å and no post-strip mobile ion contamination above 5×1010 atoms/cm². Residual metal content from the stripper is limited so that finished wafers do not exceed RoHS 2011/65/EU homogeneous material limits for lead, mercury, cadmium, or hexavalent chromium.
| Control point | Analytical method | Typical electronic/EL-grade acceptance window |
|---|---|---|
| Trace metal per element | ASTM D5673-16 inductively coupled plasma mass spectrometry | ≤ 10 µg/L |
| Chloride | ASTM D4327-17 suppressed ion chromatography | ≤ 200 µg/L |
| Sulfate | ASTM D4327-17 suppressed ion chromatography | ≤ 300 µg/L |
| Water content | ASTM E203 volumetric Karl Fischer titration | balance per formulation |
| Particles ≥ 0.2 µm | Light-scattering optical particle counter | ≤ 50 counts/mL |
AlCu backend-of-line wafers impose a narrow processing window because sulfuric acid-based stripper chemistry attacks aluminum lines at the exposed metal edge after resist breakthrough. The electronic-grade solvent-amine alternative uses hydroxylamine at 10 wt% to 15 wt%, an alkanolamine at 20 wt% to 30 wt%, catechol at 1 wt% to 3 wt%, and the balance water. The pH is held between 8.5 and 9.5. Single-wafer spray processors dispense the heated liquid through a fan nozzle at 1.0 L/min onto a wafer rotating at 800 rpm to 1200 rpm. The puddle thickness is kept between 1 mm and 2 mm for 60 s to 120 s. This mechanical shear removes swollen resist and implanted crust without oxidizing underlying titanium nitride or aluminum. Aluminum etching is measured by four-point probe sheet-resistance shift; acceptance is below 1.0 Å/min at 70 °C. Titanium nitride loss is checked by ellipsometry and kept below 0.5 nm per cleaning cycle. The stripper filtration skid uses a 0.05 µm polypropylene membrane to remove organic gels and resist debris. Post-strip defect density is tracked on a laser scanning wafer inspection tool with acceptance below 0.5 defects/cm² for the 0.16 µm bin. The process is preferred for 0.18 µm to 90 nm AlCu/tungsten logic flows where post-strip via resistance must not increase by more than 2 percent. End product is cleaned wafers with tungsten plug contact chains and no residual sulfur-bearing compounds at the aluminum sidewall.
Advanced packaging flows differ from front-end rework because thick positive photoresist films from 40 µm to 80 µm are stripped after copper electrodeposition and before nickel or gold capping. The solvent-amine bath is blended with an azole-based copper inhibitor and used at full concentration or diluted to 80 vol% depending on film thickness. The process temperature is held between 60 °C and 70 °C. At 75 °C and above, copper etch rate exceeds 0.5 µm/hour and the inhibitor loses film-forming capacity on exposed copper pillar sidewalls. Immersion tanks with nitrogen bubble agitation at 0.5 L/min per nozzle dislodge resist residues from 40 µm pitch redistribution-layer traces. A process time of 25 min to 35 min is used for 80 µm films. pH is controlled between 9.0 and 9.8 by titration with 0.1 M hydrochloric acid. Nickel and gold surfaces are protected by maintaining the working bath within 0.1 pH units of the qualified set point. The inhibitor concentration is tracked by ultraviolet-visible absorbance at 280 nm and re-established by addition of the inhibitor package. Total alkalinity is held between 1.2 eq/L and 1.8 eq/L by acid-base titration. End-product substrates are copper pillar bumps and fine-line redistribution-layer structures for flip-chip and fan-out wafer-level packages. Scanning electron microscope review at 10,000x confirms no cuprous oxide residues or organic interlayer at the Cu/Ni/Au interface.
For thin-film transistor array processing on Gen 8.5 glass, electronic-grade stripper removes organic photoresist after wet-etch patterning of molybdenum, aluminum-neodymium, and indium-tin-oxide films. The concentrate is diluted to 20 vol% to 30 vol% with ultrapure water to reduce the aluminum-neodymium etch rate. The bath is maintained at 45 °C to 50 °C. A spray or immersion time of 120 s to 180 s removes patterned resist without lifting the gate metal. The formulation contains a molybdenum-oxide chelator and a buffer to hold pH between 8.0 and 8.7. Chloride and sulfate are controlled to 200 µg/L and 300 µg/L by ion chromatography per ASTM D4327-17. Particle cleanliness after spin-dry is verified by a surface particle counter at 0.2 µm sensitivity, with acceptance of less than 100 adders per 2200 mm × 2500 mm substrate. Inline cleaner throughput on Gen 8.5 tools is typically 24 substrates/hour with two-stage cascade rinse. The process supports active-matrix organic light-emitting diode panel production with 2 µm to 4 µm channel design rules. Published data for this specific configuration is limited; validation typically uses glass substrate door tests and thin-film transistor electrical parameter drift rather than fixed standard methods.
In GaN-on-sapphire light-emitting diode back-metal rework, the electronic-grade stripper is used neat because water dilution reduces swelling of cured resist by more than half in production-scale quartz tanks. Bath temperature is set between 70 °C and 75 °C. Immersion time is 10 min to 15 min, followed by a hot deionized water rinse at 60 °C to 65 °C through a 0.1 µm polyethersulfone filter. The process targets gold-germanium and titanium-nickel stack residues after e-beam evaporation. Transition-metal impurities in the stripper are controlled by inductively coupled plasma mass spectrometry per ASTM D5673-16 with limits of 5 µg/L per element to avoid non-radiative recombination centers. Surface roughness after strip is measured by atomic force microscopy over a 5 µm × 5 µm scan area; RMS roughness remains below 1 nm. Chloride and sulfate are checked by ion chromatography per ASTM D4327-17. The bath is replenished when dissolved resist loading reaches 3 g/L. End products are near-ultraviolet and blue light-emitting diode wafers used in general lighting and automotive exterior lamp assemblies where wafer-level optical output loss after strip must remain below 1 percent.
After deep reactive-ion etching of microelectromechanical systems inertial sensor structures, sacrificial photoresist removal demands an electronic-grade stripper that does not attack silicon dioxide, aluminum nitride, or chromium-gold layers. The solvent-amine blend is applied at 20 °C to 50 °C in a quartz immersion tank with gentle rack agitation at 20 rpm. Process time is 10 min to 20 min. Low water content in the concentrated blend reduces stiction of released cantilever and comb-drive structures after drying. Total transition-metal contamination is held below 50 µg/L by inductively coupled plasma mass spectrometry. End products are accelerometers, gyroscopes, and pressure transducers with released proof masses that require no additional wet chemical cleaning before packaging.
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Stripper (Compound process) Electronic/EL Grade is a pre-blended solvent/amine formulation specified for removal of photoresist and post-etch polymer from semiconductor and compound semiconductor substrates. The compound-process designation indicates that the primary solvent, co-solvent, inhibitor package, and wetting agent are mixed and filtered before shipment; it is not a point-of-use diluted system. Supplier alphanumeric model codes vary, and procurement documentation normally identifies the product by purification train, particle filtration rating, metal ion limits, and container grade rather than by a standardized model number. The material is applied in batch immersion, spray-in-immersion, and single-wafer tools at temperatures between 40 °C and 80 °C.
Electronic/EL Grade classification places the product under front-end-of-line analytical controls. Typical specification targets are listed in Table 1; the supplier certificate of analysis is the controlling document. The product removes positive-tone novolac-type photoresist, negative-tone acrylic resists, and plasma-hardened crust from via, trench, and pad openings. The low-mobile-ion and low-particle requirements are essential for gate oxide integrity, contact resistance, and compound semiconductor surface passivation.
| Appearance | Visual inspection | Clear, free of visible particles and gel |
| Density at 25 °C | ASTM D4052 | 0.95–1.05 g/cm³ |
| Kinematic viscosity at 25 °C | ASTM D445 | 2.5–8.0 mm²/s |
| Water content | ASTM E203 | ≤0.5 wt% |
| Flash point, closed cup | ASTM D93 | ≥62 °C |
| Non-volatile residue | ASTM D1353 | ≤5 ppm |
| Metal ions (Na, K, Fe, Cu, Ca, Zn, Ni) | ICP-MS | each ≤20 ppb; total ≤100 ppb |
| Particles ≥ 0.5 µm | SEMI C1 | ≤100 particles/mL |
| Chloride | Ion chromatography | ≤500 ppb |
| Sulfate | Ion chromatography | ≤500 ppb |
Commodity solvent strippers are often supplied as technical-grade N-methyl-2-pyrrolidone or dimethyl sulfoxide blends with metal ion concentrations in the low parts-per-million range and no specified particle count. Electronic/EL Grade material is purified by multi-stage distillation and ion-exchange polishing before compounding. After blending, the product is filtered through a 0.1 µm absolute filter and filled into fluoropolymer-lined drums or high-purity polyethylene containers. This controls sodium, potassium, iron, copper, calcium, zinc, and nickel to ≤20 ppb individually and ≤100 ppb total. The commodity product may clean a wafer surface, but it does not provide the same mobile ion control for gate oxide or III-V epitaxial layers.
Point-of-use filtration of a technical-grade stripper cannot reduce dissolved metal contamination. Dissolved metals move through filtration media and remain available for adsorption onto the wafer surface during the stripping step. The Electronic/EL Grade product therefore relies on pre-shipment purification and packaging controls. Lot release testing for each container is performed at filling, and the certificate of analysis reports actual values for density, viscosity, water content, particles, metals, and non-volatile residue. Additional anion controls for chloride and sulfate are common for copper and aluminum bond pad integration.
Compared with single-solvent NMP strippers, this compound process product contains a corrosion-inhibitor package that reduces aluminum and copper attack at the pad surface. Compared with semi-aqueous strippers, the low water content of this material slows hydrolysis of the amide or ester co-solvent and reduces water-assisted corrosion on copper. Compared with reclaimed solvent systems, the Electronic/EL Grade material is not made from recovered waste solvent unless the reclaimed feedstock is re-purified to the same metal and particle limits. The difference is therefore not only solvent composition; it includes packaging, lot traceability, particle certification, and mobile ion control.
Use in production immersion tools requires a closed, nitrogen-blanketed wet bench with PTFE or 316L electropolished stainless steel tanks. The bath is held at 60 °C to 75 °C for 10–30 min for standard resist films; implant-hardened resist may require the upper temperature and longer time. For copper/low-k stacks, total contact is normally limited to 45 min at 75 °C until the dielectric is qualified. The recirculation loop includes a magnetically coupled, sealless pump and a 0.1 µm PTFE membrane cartridge. Mechanical pump seals are avoided because they shed particles into the bath and can introduce metallic contamination during long campaigns. Temperature control accuracy should be ±2 °C; above 80 °C the inhibitor package can degrade, and below 50 °C the resist-removal rate decreases enough to slow production line throughput.
Immersion bath filtration is a critical variable. A 0.1 µm absolute filter is used rather than a nominal filter because polymer particles and agglomerated gels in the bath can redeposit on wafer edges. Filter housings should be low hold-up and made of PTFE or PVDF; metallic filter housings, if used, must be polished and passivated. Filter cartridges are pre-wet with electronic-grade isopropyl alcohol before installation to avoid introducing air bubbles into the recirculation loop. During bath changes, the tank and pump heads are flushed with filtered solvent to remove residual polymer from dead legs.
Spray processors operate at 40–60 °C, with the lower temperature limiting evaporation and surface skin formation while the spray impingement provides mechanical removal. Chamber exhaust lines are heated to prevent condensation and polymer buildup. Spray tooling with excessive foaming can generate liquid level sensor faults and pump cavitation; the formulation includes a wetting agent package balanced to avoid foam accumulation in high-flow spray systems. Wafers are rinsed with ultrapure water having dissolved oxygen below 10 ppb and total organic carbon below 5 ppb. An intermediate semiconductor-grade isopropanol rinse may be used for hydrophobic low-k surfaces, provided the isopropanol is filtered to 0.1 µm.
Bath life is controlled by water absorption, inhibitor depletion, and dissolved polymer loading. Open baths exposed to ambient air above 60% RH can absorb enough water to increase surface tension and precipitate polymer. Nitrogen-blanketed systems with chilled condensers extend bath life. If Karl Fischer water content exceeds 0.8 wt%, the inhibitor package can stratify and copper pitting may occur. Dissolved polymer loading thresholds are supplier-specific; many production facilities drain the bath when polymer loading approaches 5% of bath volume or when particle counts rise above the specification limit.
The inhibitor package protects copper and aluminum-copper pads during alkaline resist removal. As a monitoring proxy, the pH of a 1% aqueous dilution typically falls between 9.5 and 11.5. The undiluted product has low water content and is not classified by pH. Depletion of the inhibitor through bath aging or water absorption can shift the open-circuit potential on copper and produce pitting or microetching. Routine bath monitoring includes water content by Karl Fischer, pH of a fixed dilution, and optical inspection of patterned pad monitor wafers.
| Silicon and polycrystalline silicon | No significant etch by ellipsometry after 30 min at 65 °C | Standard bath |
| Silicon dioxide and silicon nitride | Thickness change within measurement uncertainty after 30 min at 65 °C | Rinse/dry defect check |
| Copper | Inhibitor package prevents pad attack under standard conditions | Water ≤ 0.8 wt%; monitor pH dilution |
| Aluminum-copper | Suitable under nitrogen blanket | Avoid water uptake and chloride contamination |
| Titanium nitride and tungsten | Compatible with standard immersion times | No special control required |
| Porous low-k dielectric | Solvent absorption can shift k-value | Stack-specific qualification required; published data for specific supplier formulation is limited |
For molybdenum or ruthenium liners in advanced interconnect structures, published compatibility data for this stripper class is limited. Testing on patterned coupons before process release is required. The same applies to two-dimensional transition-metal dichalcogenide films where metal ion adsorption can dominate electrical behavior.
Single-wafer processing is selected for warped or thin wafers and for process flows in which batch immersion over-removes a passivation layer. The stripper is dispensed onto a rotating wafer, allowed to puddle for 30–90 s, and then rinsed. The short residence time requires point-of-use heating or a heated chuck, typically 45–60 °C, to maintain dissolution kinetics. Megasonic immersion at 950 kHz or 1 MHz with power density 0.3–0.5 W/cm² improves removal of plasma-hardened crust without raising the bath above 75 °C. At power density above 0.5 W/cm², acoustic cavitation can induce pattern collapse in high-aspect-ratio lines; for features below 100 nm, the process window is narrow and stacked-pattern qualification is required.
Single-wafer tools often use short dispense and puddle cycles with low liquid flow rate, followed by nitrogen blow-off. The product viscosity at 25 °C in the range 2.5–8.0 mm²/s supports film retention during the puddle step while remaining sprayable. Higher viscosity within this range favors puddle thickness and feature penetration; lower viscosity favors spray nozzle atomization. Tooling with heated exhaust lines and closed bowls avoids condensation and polymer accumulation in the chamber.
Storage, packaging, and incompatibility limits: The product is supplied in fluoropolymer-lined drums or high-density polyethylene containers under nitrogen headspace. Storage temperature should remain between 10 °C and 30 °C in a dry, well-ventilated chemical storage area. The typical shelf life is 12 months from the certified date of manufacture when unopened. Once opened, containers should be kept under nitrogen or closed immediately; ambient air above 60% RH accelerates water absorption. The product should not be mixed with strong oxidizing acids such as sulfuric acid/hydrogen peroxide mixtures or nitric acid because exothermic reactions and gas evolution can occur. Contact with strong reducing agents can destroy the inhibitor package. Equipment wetted parts should be PTFE, PFA, ETFE, or high-purity stainless steel. Viton and other fluoroelastomers may swell or extract metal compounds and should be avoided in long-term service. Spent stripper and rinse water are organic waste streams; disposal must follow site permits and applicable regulations.
In front-end-of-line production, the product is controlled through certificate of analysis review, incoming particle counting, and on-bath water/pH monitoring. The elimination of mobile ion contamination is not a bulk chemical property; it is maintained through packaging, tool materials, and operational limits.
