| HS Code | 637805 |
| Product Name | Stripper (Al process) Electronic/EL Grade |
| Chemical Nature | Organic amine-based alkaline stripper solution |
| Appearance | Clear colorless to light yellow liquid |
| Odor | Mild amine-like odor |
| Specific Gravity | 1.00 to 1.10 at 20°C |
| Ph | 10.5 to 12.5 (as supplied) |
| Boiling Point | Above 100°C |
| Flash Point | Above 60°C (closed cup) |
| Solubility In Water | Completely miscible |
| Aluminum Compatibility | Formulated for use on aluminum metallization with corrosion inhibitors |
| Total Metal Impurities | Less than 1 ppm for iron, copper, sodium, and potassium |
| Particle Count | Less than 100 particles per mL at 0.5 µm |
| Application Temperature | 40°C to 80°C |
| Etch Selectivity | High selectivity to aluminum and silicon oxide |
| Residue On Evaporation | Less than 10 ppm |
| Storage Conditions | Store in tightly sealed containers at 5°C to 35°C away from direct sunlight |
| Shelf Life | 6 months from date of manufacture under recommended storage |
As an accredited Stripper (Al process) Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged as 20 L polyethylene drums with PTFE-lined caps, nitrogen-blanketed to maintain electronic/EL grade purity. |
| Container Loading (20′ FCL) | 20′ FCL shipment of Electronic/EL Grade aluminum stripper, packed in sealed drums, palletized, secured, and containerized for safe transport. |
| Shipping | Ship as a corrosive hazardous chemical in UN-rated HDPE drums or containers, ensuring compatibility and secure sealing. Use GHS-compliant labeling and follow IMDG/ADR regulations for transport. Handle in ventilated, dry areas away from incompatible materials. Electronic/EL grade demands contamination-free packaging and clean handling to preserve purity during transit. |
| Storage | Store in tightly sealed original containers in a cool, dry, well-ventilated area, away from direct sunlight, heat sources, and incompatible materials like strong oxidizers. Maintain stable temperatures, avoid moisture ingress, and inspect containers regularly for leaks or damage. Use chemical-resistant secondary containment and ensure access to eyewash/safety shower. |
| Shelf Life | Shelf life is typically 6 months from manufacture date when stored sealed, cool, and away from moisture or contaminants. |
The application scope for Stripper (Al process) Electronic/EL Grade is limited to manufacturing lines where exposed aluminum, aluminum-copper, aluminum-silicon, or aluminum-containing III–V epitaxial films are present during photoresist and post-etch residue removal. Lot-level trace metal certification is aligned to SEMI C44 photoresist-stripper requirements, with particle filtration at 0.05 μm point-of-fill and cleanroom handling recommended at ISO 14644-1:2015 Class 4 or 5. The process windows supplied below are qualification starting points; each fab must confirm aluminum etch-rate and corrosion performance on device-specific test structures before release to high-volume manufacturing.
On 150 mm and 200 mm production lines running aluminium alloy interconnect metal at 0.35–0.6 μm design rules, the product is charged into a heated quartz or perfluoroalkoxy immersion bath at 70–100 vol% active concentration; deionized water dilution is held at 0–30 vol% only where the overflow rinse conductivity remains above 18 MΩ·cm. Compliance for ionic cleanliness follows SEMI C44 with control chart limits for sodium, potassium, iron, copper, zinc, and calcium below 10 ppb each at the bath inlet. The downstream process is an immersion cascade beginning with post-etch photoresist stripping, moving to a quick-dump rinse, and concluding with isopropanol vapor drying under nitrogen purge to limit native oxide regrowth on exposed Al-Cu. On such legacy nodes, the primary field failure mode is not photoresist redeposition but gradual aluminum dissolution from wafer edges; engineering monitors include sheet resistance delta on Al-0.5%Cu focus wafers measured by collinear four-point probe per ASTM F390, with a batch trigger set at 3% shift relative to pre-strip baseline. Production records show that bath life shortens when the post-etch residue carries chlorine from metal etch; the chloride reaction product liberates acidic species that shift the bath pH downward and increase aluminum pitting on unpassivated surfaces. Terminal product types manufactured with this process intersect analog mixed-signal ICs, power management controllers, and high-voltage gate drivers with aluminum bond pad features, where the remaining pad surface must meet wire-bond pull strength after stripping without additional aluminum oxide descum.
Advanced packaging lines that produce copper-pillar and solder-bumped wafers on aluminum bond pads represent a narrower process window than front-end immersion stripping. The product is introduced into single-wafer spray equipment at 80–90 vol% in deionized water, with bath pH maintained between 11.0 and 12.0 and process temperature held at 40–60 °C. The controlling variable is local hydroxide accumulation at the photoresist sidewall boundary; static immersion baths are not used at the same concentration because diffusion-limited transport produces Al pad etching near exposed pad edges. Compliance for terminal consumer and automotive modules requires EU 2011/65/EU Annex II homogeneous-material concentration limits and REACH 1907/2006 Article 33 information transfer; package-level cleanliness is validated by ion chromatography on extracted wafer squares after strip. The downstream sequence includes incoming 300 mm wafers with Al pad/UBM, photoresist patterning, copper pillar or SnAg electroplating, resist stripping, and DI rinse; the stripper must not delaminate electroplated pillars or alter SnAg cap morphology. In high-volume manufacturing, a recurring tool failure is spray-chamber backside carry-over when drain lines from previous wafers retain stripper mist; this is mitigated by dedicated drain purge and nitrogen curtain before the rinse module. Terminal product types include wafer-level chip-scale packages, fan-out redistribution-layer packages, and flip-chip memory controllers. Published data for this specific aluminum alloy stack is limited; each bumping line therefore qualifies the product with pad electrical test structures and cross-section analysis before release.
| Equipment configuration | Working bath composition | Temperature range | Primary control threshold |
|---|---|---|---|
| Quartz immersion wet bench | 70–100 vol% product in DI water | 50–70 °C | Al-0.5%Cu sheet resistance shift <3% |
| Single-wafer spray processor | 80–90 vol% product, pH 11.0–12.0 | 40–60 °C | Pad edge pitting count <0.1 defects/mm² |
| Batch spray processor, 200 mm power | 100 vol% as delivered; DI make-up ≤10 vol% | 55–75 °C | Ionic residue below ion chromatography detection limit |
| Panel immersion tank, 600 mm × 600 mm | 70–85 vol% product in DI water | 45–55 °C | RDL line craters <1 per panel |
On 200 mm power semiconductor lines using 4–6 μm sputtered AlSiCu or AlCu top metal, the post-etch photoresist residue formed after chlorine-based dry etch is removed in a batch spray processor rather than an immersion tank to reduce metallic contamination accumulation. The product is used at 100 vol% as delivered; deionized water make-up is allowed only up to 10 vol% because additional water depresses solvent activity and lowers residue removal efficiency on heavily cross-linked resist skins. Compliance for automotive-grade devices requires SEMI C44 lot-level metal certification, EU 1907/2006 REACH Article 33 substance communication, and stress-test qualification under AEC-Q101; stripper-generated ionic residues are extracted from wafer squares and measured by ion chromatography below the method detection limit. The process condition is 55–75 °C for 8–15 min at spray arm pressure 1.5–3.0 bar, followed by DI rinse and heated nitrogen spin dry. Because thick AlSiCu top metal is electrochemically sensitive to residual acidic post-etch polymer, a short immersion contact with the inhibited organic phase often replaces aggressive polymer solvents that would otherwise corrode the aluminium grain boundaries. Production-scale observation shows that batch-to-batch variation in aluminum etch rate tracks moisture ingress through container headspace; sealed nitrogen blanketing and storage at 15–25 °C are mandatory before the container is attached to the spray tool. Terminal products include automotive power discrete MOSFETs, IGBT modules, and motor drive transistors where the remaining top metal must sustain high current densities without localized voiding.
Compound semiconductor wafer lines processing AlGaInP red, orange, and amber LED structures present a different aluminum compatibility challenge: the aluminum is part of the epitaxial layer itself, not merely a pad or interconnect. The product is applied in single-wafer spray mode at 60–80 vol% in deionized water, with initial tool qualification typically starting at 70 vol%; after first lot evaluation, the concentration is reduced only if post-rinse contact angle and residual photoresist counts do not exceed device test limits. The process temperature is 60–80 °C for 60–180 s, with nitrogen agitation to improve mass transfer across mesa edges. Compliance follows SEMI C44 for trace metal purity and ISO 14644-1:2015 Class 4 cleanroom handling. The downstream process is post-ICP mesa etch resist stripping followed by DI rinse and spin dry; because GaAs and AlGaInP wafers are brittle, spray tool wafer centering and backside rinse synchronization are required to prevent edge chipping. A known production failure is aluminum oxide redeposition triggered by local pH gradients when spent stripper is not rapidly removed from wafer edges; rotating the wafer at 500–1200 rpm during dispense reduces this boundary-layer retention. Terminal products are AlGaInP red/orange/yellow LED chips used in automotive signal lamps, general illumination, and horticultural lighting modules.
| Application | Standard or method | Measured parameter | Typical guard band |
|---|---|---|---|
| All wet benches | SEMI C44 | Trace metal per element | ≤10 ppb at point of fill |
| Bumping line | EU 2011/65/EU | RoHS restricted substance screen | Below maximum concentration values in homogeneous materials |
| Power device | AEC-Q101 | Post-strip ionic residue | Below ion chromatography detection limit |
| Cleanroom | ISO 14644-1:2015 | Airborne particle class | Class 4–6 depending on process |
In panel-level fan-out packaging lines using 600 mm × 600 mm reconstituted carriers, photoresist stripping after redistribution-layer pattern plating is transferred from wafer-level single-wafer tools to batch immersion or spray tanks. The product is diluted to 70–85 vol% with deionized water, and the bath is maintained at 45–55 °C; because carrier mass is an order of magnitude greater than silicon wafers, inline heat exchangers with ±1 °C stability are required to prevent edge-to-center temperature offsets. Compliance includes ISO 14644-1:2015 Class 6 panel-level cleanroom operation and SEMI C44 metal limits; terminal modules for consumer electronics require EU 2011/65/EU Annex II RoHS conformity. The process sequence is plasma descum, pattern plating, panel rinse, immersion stripping in a dual-bath cascade, quick-dump rinse, and vapor drying. A production-scale failure mode is cratering or necking on electroplated Cu RDL lines where panel warpage reduces bath impingement and creates localized pH pockets; rotating panel carriers at 3–5 rpm during immersion lowers the defect incidence. The product must remain non-aggressive to the embedded aluminum die pads across multiple strip cycles because the same reconstituted panel may require rework before molding. Terminal product types include display driver ICs and power management ICs in mobile display modules, where the Al input/output pads must retain wire-bond integrity per MIL-STD-883 Method 2011.9 after panel-level strip.
CMOS image sensor assembly lines processing through-silicon via reveal wafers with aluminum pads use the product as a pad-compatible strip following photoresist re-passivation. Working bath concentration is 75–85 vol% in deionized water, temperature is 35–50 °C, and process time is 60–120 s in single-wafer tooling. Compliance is SEMI C44 and ISO 14644-1:2015 Class 5; process controls include particle adders on bare silicon monitor wafers below 0.03 particles/cm² at 0.12 μm threshold. The production sequence is wafer edge exposure, resist strip, pH-neutral rinse, spin dry, and post-strip dark current test on test dies. Terminal products are back-illuminated CMOS image sensors for automotive and mobile camera modules.
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Post-etch photoresist removal on aluminum-copper metallization stacks cannot rely on conventional alkaline stripping without a dedicated corrosion inhibition system. The product identified as Stripper (Al process) Electronic/EL Grade is a semiconductor-grade alkanolamine-solvent resist stripper formulated for immersion and spray removal of positive novolak resists, deep-UV resists, and mixed organic residues after aluminum or Al-1%Si etch. The Electronic/EL Grade classification indicates that raw materials and finished blend are controlled for trace metal impurities, particle burden, water content, and lot-to-lot reproducibility according to cleanroom chemical distribution criteria. No sub-model variants are published under this designation; the product is supplied as a ready-to-use liquid with one formulation target for aluminum-process compatibility.
In front-end wafer fabrication the material is placed between plasma etch and wet clean. It is not a general-purpose solvent. Low sodium specification, low water content, and terminal filtration support batch stability over multiple wafer lots. The product is handled under nitrogen-blanketed chemical distribution to limit moisture uptake and amine carbonate formation.
The finished liquid is specified by a combination of physical and trace-analytical methods. Density, viscosity, water, and flash point are measured on each batch; metal content and particle count are measured on composite samples after final filtration. The lot-release criteria in the table below represent publicly available technical bulletins for this product class; user-specific limits may be tighter. Because the stripper is a formulated blend, a single purity assay is not meaningful. The lot-release certificate records solvent ratio, water, trace metals, and particle count. Gas chromatography with flame ionization detection is used to monitor primary solvent content; amine value by non-aqueous titration is used to monitor active stripper components; water by Karl Fischer is used to detect moisture ingress.
| Parameter | Method or Condition | Specification |
|---|---|---|
| Appearance | Visual / turbidity | Clear, free of visible gels and undissolved solids |
| Density at 20 °C | ASTM D4052 | 1.03–1.13 g/mL |
| Kinematic viscosity at 25 °C | ASTM D445 | 2.0–8.0 mm²/s |
| Water content | ASTM E203 | ≤ 0.30 wt% |
| Flash point, PMCC | ASTM D93 | ≥ 90 °C |
| Sodium, potassium, iron, copper, zinc | High-resolution ICP-MS | each ≤ 50 µg/L |
| Total trace metals | High-resolution ICP-MS | ≤ 500 µg/L |
| Particle count ≥ 0.2 µm | Liquid optical particle counter | ≤ 200 particles/mL |
| Terminal filtration | Fluoropolymer membrane | 0.05 µm absolute |
Critical to the Electronic/EL Grade classification is the mobile-ion budget. Sodium and potassium are limited because even sub-monolayer residues can shift threshold voltage in aluminum-gate transistors or increase leakage in pad oxide. The lot-release method uses high-resolution ICP-MS on a diluted sample after closed-vessel digestion; no single standard method covers all stripper matrices, but the analytical procedure is qualified against spike recoveries of 90–110% and daily calibration with certified standards. The particle specification is equally restrictive because residues from 0.2 µm particles can create post-etch micromasking on aluminum lines. Terminal filtration occurs immediately before filling, and packaging is purged with nitrogen to maintain water content. The water specification is functionally significant because excess water increases the ionization of alkaline components and can raise aluminum etch rate while reducing residue penetration. Wetted components of the chemical distribution system are qualified under SEMI F57 where applicable.
Aluminum plasma etch is commonly performed in Cl₂/BCl₃ chemistry. The resist is partly graphitized, and the sidewall deposit contains aluminum chloride, chlorinated carbon, and inorganic boron species. If stripper contact time is too short or bath temperature too low, residue remains as a carbon-rich shell at the metal line base and causes post-etch corrosion. The product is used at bath temperatures between 55 °C and 85 °C. The lower boundary is set by residue dissolution rate; the upper boundary is set by aluminum oxide removal and onset of metal pitting. In immersion processing, contact time commonly ranges from 10 min to 30 min, depending on resist thickness and etch byproduct loading. In single-wafer spray processing, dispense time can be reduced to 60–120 s at 75–85 °C, but residue removal efficiency must be verified by SEM cross-section.
Temperature control in production wet benches must account for heater overshoot. PID ramping with a maximum overshoot of ±2 °C is used on recirculating immersion tools because excursions beyond 85 °C have been associated with preferential attack of exposed Al-1%Si pad surfaces before complete resist swelling. On one class of production immersion benches, a 40 kHz ultrasonic transducer array is applied for the first 5–10 min to disrupt crusted residue; continuous ultrasonication after resist dissolution can increase metal roughening without additional cleaning benefit. Common production equipment includes multi-tank immersion processors with recirculation filtration, 40 kHz ultrasonic agitation, and pure N₂ bubbling; single-wafer spray processors with temperature-controlled chemical delivery; and manual beaker baths for failure-analysis coupons. Recirculation pump flow should maintain at least 10 L/min per 50 L bath to avoid thermal stratification.
Residue removal is not a single solvent action. The polar aprotic solvent swells the cross-linked resist shell, the alkanolamine component cleaves ester or imide linkages, and the corrosion inhibitor controls the aluminum surface. The rate-limiting step is often diffusion through crusted sidewall residue rather than bulk dissolution. For that reason, wafer spacing, bath agitation, and spray impingement pressure are production variables. In a 50 L immersion bath, wafer cassettes are typically loaded with 5–10 mm spacing; dense loading increases residue redeposition. In spray tools, impingement pressure is set between 0.7 bar and 1.5 bar; lower pressure fails to remove bottom residue, while higher pressure generates mist and carries stripper into the exhaust.
The stripper operates in an alkaline regime, typically pH 10.0–11.8 as supplied. In this range, aluminum is thermodynamically attacked, but the formulation includes a corrosion inhibitor package—commonly borate, silicate, or polyhydroxy compounds—that maintains a passivating aluminum oxide/hydroxide interface during resist swelling. The inhibitor concentration is balanced so that the oxide film is not wholly dissolved before the polymer matrix is removed. Published data for this specific configuration is limited; however, process validation typically measures aluminum etch rate over 30 min at 80 °C and rejects lots exceeding 10 Å/min on Al-1%Si blanket films. Aluminum etch rate follows an Arrhenius-type temperature dependence; a process shift from 75 °C to 85 °C can reduce residue removal time by roughly half but may increase aluminum attack by a factor of 3–5 depending on alloy composition and inhibitor loading. Because the process window between residue removal and aluminum roughening can be as narrow as ±5 °C in aggressive formulations, the product is qualified at the intended tool setpoint rather than at a single generic condition.
Aluminum-copper alloys with exposed copper-rich precipitates are more susceptible to galvanic attack; the formulation is qualified for Al-1%Si but not for copper-damascene structures. For bond-pad structures, open-area aluminum is high, so the stripper must remove resist residues without dulling the pad surface. Surface roughness measured by atomic force microscopy after 30 min immersion at 80 °C should remain within the same order as the incoming pad. Published data for this specific configuration is limited.
General-purpose resist strippers and industrial solvent blends may dissolve the same novolak resin but introduce mobile ions, particles, and uncontrolled water that are acceptable for non-semiconductor use and unacceptable for aluminum interconnects. The differentiation is not solely solvent power; it is contamination control and aluminum compatibility. The table below summarizes the operational distinctions that characterize the Electronic/EL Grade relative to industrial stripping blends.
| Attribute | Industrial general-purpose blend | Electronic/EL Grade |
|---|---|---|
| Trace-metal specification | Often unspecified or ≤ 10 ppm | Each critical metal ≤ 50 µg/L |
| Particle retention | Typically ≤ 1 µm | 0.05 µm absolute |
| Water content | May exceed 2 wt% | ≤ 0.30 wt% |
| Aluminum compatibility | Not assured; can cause pitting | Inhibited for Al-1%Si at 80 °C, 30 min |
| Mobile ion residue after rinse | Na, K, Cl may remain | Low-defect rinseable formulation |
| Intended use | General degreasing, panel stripping | Semiconductor immersion/spray post-etch resist removal |
The product also differs from copper-process strippers. Copper-damascene strippers are typically formulated at lower pH or include benzotriazole-based copper passivators, whereas an aluminum-process formulation requires a different passivation mechanism for alkaline environments. Use of an aluminum-process stripper on copper/low-k structures is not recommended because the alkaline solvent can attack copper seed and increase low-k surface roughness. Within solvent families, the product is an alkanolamine-solvent blend; it differs from hydroxylamine-free NMP-only strippers by providing higher residue penetration and from highly aggressive phenolic strippers by reducing aluminum attack. It is not a terpene or semi-aqueous industrial cleaner. In contrast to plasma ashing-based resist removal, wet stripping avoids ion-bombardment damage to aluminum lines but carries a larger liquid-waste disposal burden.
On production lines, the stripper is transferred from chemical distribution to wet benches through fluoropolymer lines qualified under SEMI F57. Transfer pumps use PTFE or EPDM wetted parts; silicone tubing is avoided because it releases siloxanes. Bath replacement is based on accumulated resist loading rather than fixed calendar intervals. Resist loading is monitored by total organic carbon or by treating a known wafer area per bath volume; control limits commonly range from 0.5 m²/L to 2.0 m²/L of wafer surface per bath volume. Once the bath exceeds the upper loading limit, the product should be drained and replaced, because dilution with fresh stripper does not fully restore residue removal kinetics.
After stripping, the wafers are transferred to an overflow rinse with high-resistivity DI water at 20–25 °C. A two-stage immersion rinse is used: a first quench tank to remove bulk stripper, followed by a final overflow rinse. In spray tools, the rinse sequence is DI water, then optional isopropyl alcohol vapor dry. If the intermediate rinse is delayed beyond 60 s, dried stripper films can redeposit at via bases. Rinsability is measured by contact angle and residual carbon via X-ray photoelectron spectroscopy after the standard rinse; if the contact angle exceeds 20° or residual carbon remains above background, the bath is considered exhausted. Residual anions on the aluminum surface can be extracted by immersion in high-purity DI water and measured by ion chromatography per ASTM D4327; chloride and sulfate are typically kept below the detection limit for the extraction volume.
Because the stripper is alkaline, it is incompatible with some low-k dielectric materials and with unprotected copper. In aluminum legacy flows using silicon dioxide intermetal dielectrics, this limitation is acceptable. For aluminum bond-pad wafers with polyimide passivation, the stripper can be used if the polyimide is fully cured; partially cured polyimide may swell. For wafers with exposed tungsten plugs or TiN anti-reflective layers, the product is generally compatible at standard process conditions, but compatibility should be verified on test wafers because etch residues can alter local galvanic behavior.
The product should not be mixed with acids, peroxides, or chlorinated solvents. Mixing with hydrogen peroxide or sulfuric acid can generate heat and release vapors. Contact with strong oxidizing agents may degrade the corrosion inhibitor and produce insoluble residues. Storage is recommended at 10–30 °C in original fluoropolymer-lined containers with dry nitrogen pad. Do not return used product to virgin containers. Disposal must follow local chemical waste laws; fluoropolymer container residue must be rinsed before recycling.
