| HS Code | 400255 |
| Chemical Name | Semiconductor Plating Solution Electronic/EL Grade |
| Grade | Electronic/EL (Electronic Level) |
| Appearance | Clear liquid, free of visible particulates |
| Color | Colorless to very pale yellow |
| Purity | ≥ 99.99% (metals basis) |
| Density | 1.10 ± 0.05 g/cm³ at 25°C |
| Ph | 4.5 ± 1.0 at 25°C |
| Total Metal Impurity Content | ≤ 10 μg/L |
| Individual Metal Impurity Content | ≤ 1 μg/L per element |
| Particle Count | ≤ 100 particles/mL at ≥ 0.2 μm |
| Refractive Index | 1.34 - 1.40 at 20°C |
| Viscosity | 1.0 - 2.0 cP at 25°C |
| Boiling Point | Approximately 100°C at 1 atm |
| Water Solubility | Fully miscible |
| Storage Life | 12 months in unopened original container |
As an accredited Semiconductor Plating Solution Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 1 L HDPE bottle with tamper-evident seal, certified Electronic/EL grade for semiconductor plating. Labeled with safety and purity information. |
| Container Loading (20′ FCL) | 20′ FCL: drums/IBCs of Electronic/EL Grade semiconductor plating solution, securely palletized, labeled, and containerized for safe transport. |
| Shipping | Semiconductor Plating Solution Electronic/EL Grade should be shipped in leak-proof, UN-approved containers, securely sealed and upright. Label per current SDS with appropriate hazard markings. Transport in ventilated, temperature-controlled vehicles, avoiding extreme heat or freezing. Keep away from incompatible materials. Provide spill response documentation and confirm all regulatory requirements with the carrier before dispatch. |
| Storage | Store in original, tightly sealed containers under clean, temperature-controlled conditions to prevent contamination and degradation. Keep away from direct sunlight, oxidizers, and incompatible chemicals. Use dedicated, corrosion-resistant storage areas with proper ventilation. Maintain inventory rotation and monitor expiration dates to ensure purity and consistent electronic/EL-grade performance. |
| Shelf Life | Shelf life is typically 6–12 months when stored sealed, cool, and protected from light; once opened, use promptly to avoid contamination. |
Electrolytic copper fill for dual-damascene interconnect structures at the 5 nm and 7 nm logic nodes requires a low-copper/high-acid virgin make-up bath prepared from electronic/EL-grade copper sulfate pentahydrate and semiconductor-grade sulfuric acid, with chloride ion controlled in the 20–80 ppm window. The bath is operated at 25–28°C in a fountain-type or segmented-insoluble-anode wafer plating cell equipped with 0.1 µm PTFE filtration and continuous online brightener analysis by cyclic voltammetric stripping. Bottom-up fill is achieved through the competitive adsorption of bis(3-sulfopropyl) disulfide accelerator, a polyethylene glycol suppressor, and a leveler such as Janus Green B or a specified polymeric amine; the accelerator accumulates on the flat field and via bottoms during electrodeposition, while the suppressor and leveler regenerate on the upper sidewalls. This additive balance is disturbed by transition-metal impurities above 0.5 ppm iron or 0.1 ppm nickel, which can suppress acceleration and produce center voids or seam lines. The sulfuric acid fraction is qualified against SEMI C27 trace metal criteria and the copper sulfate fraction against a supplier certificate of 99.999% minimum purity, with individual alkali and transition metals below 1 ppm and total organic carbon below 100 ppb. Terminal devices include logic processors with Cu/low-k interconnect stacks, DRAM buried wordline/bitline metallization, and 3D NAND wordline connections; the same bath is not suitable for tin or lead alloy deposition because residual copper ions exceeding 10 mg/L in a subsequent solder bath can generate intermetallic precipitate defects and bump-level voiding.
| Parameter | CuSO₄·5H₂O electronic/EL grade | H₂SO₄ electronic/EL grade | Analytical method |
|---|---|---|---|
| Purity | 99.999% minimum | 96.0% minimum | Assay by titration or gravimetry |
| Chloride | ≤1 ppm | ≤0.1 ppm | Ion chromatography |
| Iron | ≤0.5 ppm | ≤0.05 ppm | ICP-MS |
| Nickel | ≤0.1 ppm | ≤0.05 ppm | ICP-MS |
| Total organic carbon | ≤100 ppb | ≤50 ppb | UV/persulfate oxidation |
For through-silicon via arrays with via diameters of 5–20 µm and depths of 50–300 µm, the plating chemistry is distinguished from damascene by the requirement to maintain suppressor coverage on the via mouth for an extended period while the accelerator builds at the via bottom. The deposition current density is typically ramped from 0.5–3 mA/cm² during the initial bottom-up nucleation phase to 10–20 mA/cm² after bottom coverage exceeds 30–40%. Reverse pulse plating with a forward-to-reverse charge ratio near 10:1 and reverse pulse duration of 5–20 ms reduces mouth closure in vias with aspect ratio 10:1 and higher, but excessive reverse charge strips the accelerator from the bottom seed and creates a characteristic mid-via void. Bath formulations for through-silicon via commonly use copper sulfate pentahydrate at 0.8–1.0 mol/L, sulfuric acid at 0.5–0.8 mol/L, chloride at 40–70 ppm, and three-component additive packages that are mixed on-site after 0.1 µm filtration; electronic/EL-grade water per ASTM D5127-13(2018) is mandatory for make-up and rinsing because dissolved silica and colloidal particles above 5 ppb seed nodule growth on the via sidewall. Production-scale failure modes observed in high-aspect-ratio through-silicon via plating include leveler concentration drift after 500–700 Ah/L bath age, which causes top pinch-off, and accelerator oxidation when the bath temperature is not held below 28°C. Terminal products include silicon interposers for high-bandwidth memory stacks, 2.5D logic-on-interposer assemblies, and 3D hybrid bonding test vehicles where the filled via cross-section is inspected by scanning acoustic microscopy after annealing at 350°C for 1 h.
For copper pillar and redistribution-layer plating on 150 mm and 300 mm wafers, the bath shifts toward high-acid, high-plating-rate operation because the target deposits are 30–100 µm thick and the current densities reach 20–60 mA/cm². A representative high-throw bath contains copper at 40–60 g/L, sulfuric acid at 180–220 g/L, chloride at 50 ppm, and a leveler system designed to suppress overplating on isolated features and promote uniform deposition across dense and sparse pillar arrays. EL-grade purity is critical for the acid component because the large replenisher volume consumed in thick-film plating can import transition metals; a single 200 L bath with iron at 1 ppm can generate nodular growth on 80 µm pillar sidewalls within 40–60 wafer passes. The plating tool is an open-top cup or fountain cell with wafer rotation between 20–100 rpm, segmented anodes, and membrane-separated anolyte to prevent organic additive oxidation by the anode. Photoresist compatibility defines the additive set: certain nitrogen-containing levelers plasticize positive-tone novolac resists and are replaced with sulfur-terminated levelers for tall pillar structures. Terminal products are flip-chip copper pillars under solder tips, redistribution traces in fan-out wafer-level packaging, and passive integrated devices on glass or silicon, where sheet resistance after seed etch and annealing at 200°C for 30 min is measured by a four-point probe against the design linewidth.
For electroplated Sn-Ag bumps, the methanesulfonic acid system is preferred because it avoids cyanide and permits tin and silver co-deposition at low pH. The bath contains tin methanesulfonate at 50–80 g/L tin, silver methanesulfonate at 0.8–1.5 g/L silver, methanesulfonic acid at 150–200 g/L, and a specified set of antioxidants, grain refiners, and levelers. Silver content in the deposit is controlled to 2.0–3.5 wt% with a tolerance of ±0.3 wt% across a 200 mm wafer; deviations beyond this range produce tin dendritic growth at low silver or Ag₃Sn platelet formation at high silver, both of which reduce shear strength after reflow. The plating current density is typically 1–5 A/dm² at 20–30°C, with low-alpha tin required for high-reliability flip-chip applications and alpha emitter levels specified below 0.005 counts/h/cm² for components used near image sensors and high-speed serial links. The bath is incompatible with chloride contamination above 10 ppm because chloride precipitates silver as AgCl and shifts alloy composition; therefore, make-up water must meet ASTM D5127-13(2018) Type E-1 requirements and all rinse lines must be constructed of chloride-free fluoropolymers. End products are wafer-level chip-scale packages, automotive radar devices, and power management ICs where the solder bump is reflowed at 250–260°C and inspected by X-ray for voiding below 3% of bump volume, consistent with RoHS 2011/65/EU lead-free requirements.
| Impurity | Maximum limit | Analytical method | Defect consequence if exceeded |
|---|---|---|---|
| Lead | 20 ppm | ICP-MS | Alpha-emitter increase, solder joint embrittlement |
| Copper | 10 ppm | ICP-MS | Intermetallic precipitation, plating roughness |
| Iron | 10 ppm | ICP-MS | SnFe particle formation, bump lift after reflow |
| Chloride | 10 ppm | Ion chromatography | AgCl precipitation, silver composition drift |
| Alpha emitters | 0.005 counts/h/cm² | Alpha spectroscopy | Soft error rate increase in adjacent logic |
Because III-V and quartz-based surface acoustic wave devices require bump heights below 25 µm with tight hardness control, gold bump plating uses either potassium gold cyanide or gold sulfite chemistry, and the selection between the two is controlled by photoresist compatibility and the tolerable cyanide exposure of the underlying metal stack. Cyanide baths formulated with 8–20 g/L gold as potassium gold cyanide and free potassium cyanide at 20–60 g/L operate at 60–70°C and 0.5–2 A/dm², producing a deposit hardness of 60–90 HV and a purity of 99.99%. Sulfite baths, in contrast, operate in the pH 7–9 range at 50–60°C and are used where cyanide attack on aluminum bond pads or exposed III-V features is unacceptable, but the sulfite ion must be stabilized with sulfite and thiosulfate suppressors to prevent decomposition. The EL-grade requirements for gold bump baths focus on trace thallium, lead, copper, and nickel, with individual concentrations below 1 ppm, because these metals co-deposit and alter bump hardness and wire bondability. Seed layer adhesion at the photoresist opening is tested after plating onto TiW/Au or Cr/Au stacks, and the plated bump shear strength is recorded against a 25 µm thickness specification. Terminal applications are RF front-end modules, GaAs pseudomorphic high-electron-mobility transistor wafers, InP photodiodes, and quartz crystal microbalances.
When aluminum bond pads cannot be processed through PVD seed metal deposition, electroless nickel-palladium-gold under-bump metallization plating solutions are used, and the electronic-grade conditions concern the electroless nickel bath’s stability against trace copper and iron contamination. The nickel bath contains nickel sulfate hexahydrate at 20–30 g/L nickel, sodium hypophosphite at 20–30 g/L, and low-temperature complexing agents that maintain deposition at 80–90°C with pH 4.5–5.5; the palladium bath is operated at 50–60°C with palladium sulfate at 1–5 g/L, and the immersion gold bath uses 0.5–2 g/L gold as potassium gold cyanide at 80–90°C. EL-grade purity is mandatory because metallic impurities in the hypophosphite or nickel salt trigger bath decomposition and produce nodular nickel with phosphorus content outside the 7–9 wt% window. The resulting under-bump metallization stack has acceptable wire-bond and solder-joint reliability, but the process is incompatible with aluminum pads smaller than 50 µm pitch due to lateral overgrowth, and it is sensitive to dissolved oxygen in the immersion gold stage. Terminal products are display driver ICs, analog mixed-signal controllers, and automotive microcontrollers using copper wire bonding.
In integrated inductors and magnetic MEMS, nickel-iron permalloy electrodeposition uses a sulfate/chloride electrolyte with nickel sulfate 0.2–0.5 mol/L, ferrous sulfate 0.01–0.05 mol/L, boric acid 0.4–0.6 mol/L, and saccharin 1–3 g/L as a stress reducer and grain refiner. The Fe(II) concentration must be controlled within ±5% of the target because the NiFe alloy composition near 80:20 wt% Ni:Fe determines zero magnetostriction and peak permeability; ferrous ion oxidation to ferric above 10 mg/L produces rough deposits with reduced magnetic saturation. Plating is performed at 20–30°C with current density 5–20 mA/cm², and the EL-grade criteria include total transition metals below 1 ppm and total organic carbon below 50 ppb. Terminal products are on-chip inductors in RF transceivers, magnetic sensor bridges, and micromechanical switches; the same bath cannot be used for aluminum or copper redistribution because the sulfate/chloride mixture etches aluminum at low pH.
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Semiconductor Plating Solution Electronic/EL Grade is supplied as three process-specific liquid formulations: EL-Cu A300 for acid copper damascene and redistribution layer metallization, EL-Sn B150 for tin-silver solder bumping, and EL-Ni C200 for electrolytic nickel under-bump metallization. The Electronic/EL designation defines a control envelope covering trace-metal content, particle burden, total organic carbon, major-component stability, and packaging integrity rather than a single composition. Each lot is filtered through 0.1 µm-rated fluoropolymer membranes and filled into fluoropolymer-lined drums under dry nitrogen in an ISO 14644-1 Class 4 cleanroom. Certificate of analysis values are generated by inductively coupled plasma mass spectrometry per ISO 17294-2, ion chromatography per ISO 10304-1, total organic carbon oxidation per ISO 8245, viscosity measurement per ISO 3104, density measurement per ISO 12185, pH measurement per ISO 10523, and conductivity measurement per ISO 7888. The formulations differ from reagent-grade and technical-grade plating baths primarily in the reduction of transition-metal impurities below 5 ppb per element and the control of sub-micron particles below 50 counts/mL for particles at or above 0.5 µm.
The distinction lies in particle and trace-metal control rather than in base chemistry. Reagent-grade copper sulfate may carry transition-metal contamination at 0.1–1.0 ppm per element and particulate matter above 10 µm at counts that are not lot-controlled. Technical-grade formulations often contain organic residues from raw materials, broad chloride variability, and no defined packaging atmosphere. In patterned copper plating, iron contamination above 10 ppb can shift suppressor adsorption and increase void-seam incidence in vias of 90 nm or smaller; particulate contamination above 0.5 µm can nucleate nodule defects at wafer edge. The Electronic/EL Grade therefore specifies every contaminant transition metal at or below 5 ppb, total non-Cu metals at or below 25 ppb, chloride in the acid copper formulation at 50–80 mg/L, and total organic carbon below 20 mg/L. Packaging under nitrogen limits oxygen ingress that oxidizes Sn(II) in methanesulfonic acid baths and degrades accelerator components in acid copper baths.
| Attribute | Electronic/EL Grade | Reagent Grade | Technical Grade |
|---|---|---|---|
| Transition metal per element | ≤5 ppb | 0.1–1.0 ppm | ≥1 ppm |
| Total non-Cu metals | ≤25 ppb | not specified | not specified |
| Particles ≥ 0.5 µm | ≤50 counts/mL | ≥10³ counts/mL | not measured |
| Total organic carbon | ≤20 mg/L | 50–200 mg/L | not controlled |
| Packaging atmosphere | dry nitrogen, fluoropolymer-lined | uncontrolled | uncontrolled |
| Lot traceability | certificate of analysis per lot using ISO methods | limited | none |
Representative analytical profiles for the three process-specific formulations are controlled by lot-specific certificate of analysis values tied to certified reference materials. EL-Cu A300 is an acid copper sulfate system with copper ion content of 20–40 g/L as Cu, sulfuric acid content of 30–50 g/L, chloride at 50–80 mg/L, density of 1.15–1.20 g/cm³ at 20 °C per ISO 12185, viscosity of 1.5–2.5 mPa·s at 20 °C per ISO 3104, and conductivity of 200–300 mS/cm at 25 °C per ISO 7888. The organic additive package is proprietary and is monitored by cyclic voltammetric stripping; accelerator concentration is held within ±0.05 mL/L of the qualified setpoint. EL-Sn B150 is a methanesulfonic acid tin-silver bath with tin content of 40–60 g/L as Sn, silver content of 0.4–0.8 g/L as Ag, free acid of 120–180 g/L as methanesulfonic acid, density of 1.20–1.25 g/cm³ at 20 °C, and a proprietary antioxidant to maintain dissolved oxygen below 0.5 mg/L under nitrogen blanketing. EL-Ni C200 is a sulfamate nickel bath with nickel content of 60–90 g/L as Ni, boric acid at 30–40 g/L, pH of 3.5–4.0 per ISO 10523, and surface tension below 40 mN/m at 25 °C. Particle counts for all three models are specified at ≤50 counts/mL for particles at or above 0.5 µm when measured by a laser particle counter calibrated to ISO 21501-4.
Storage and handling conditions are part of the Electronic/EL guarantee. The solutions are stored at 10–25 °C; temperatures below 5 °C can crystallize copper sulfate pentahydrate in EL-Cu A300, and temperatures above 30 °C accelerate methanesulfonic acid oxidation in EL-Sn B150. Drums are purged with nitrogen after each withdrawal, and the product should not be transferred through unpassivated stainless-steel lines because iron leaching can exceed 5 ppb within 24 h. Point-of-use filtration is maintained with 0.1 µm-rated polypropylene filters, with filter replacement triggered by differential pressure above 1.0 bar. The product is supplied in 20 L and 200 L fluoropolymer-lined drums. Shelf life from date of manufacture is 12 months when stored unopened under nitrogen; after opening, the recommended consumption period is 60 days.
Patterned wafer plating places separate demands on bath stability and mass transport. In a 300 mm fountain cell with segmented insoluble anodes, wafer rotation of 300 rpm, recirculation flow rate of 20 L/min, and bath volume of 200 L, the acid copper formulation is operated at 2.0–4.5 A/dm² and 25 °C ± 0.5 °C. Within this window, bottom-up fill is maintained by the interaction between accelerator, suppressor, and chloride. Accelerator consumption is measured by cyclic voltammetric stripping and is typically 0.3–0.7 mL per ampere-hour; suppressor consumption is 0.1–0.3 mL per ampere-hour; leveler consumption is 0.05–0.15 mL per ampere-hour. Below 2.0 A/dm², the leveler is consumed too slowly and its accumulation produces overplating bumps over isolated features. Above 4.5 A/dm², suppressor depletion at the via bottom generates void seams. Bath life is not limited by metal depletion alone; oxidation byproducts from the insoluble anode and chloride loss through drag-out shift the cyclic voltammetric stripping response after approximately 120 operating hours or 40 ampere-hours per litre, whichever occurs first. When the bath is idle, it is blanketed with nitrogen at 0.2–0.5 bar positive pressure. Agitation is supplied by eductor recirculation rather than air sparging; air sparging oxidizes the accelerator and raises particle counts above the specified 50 counts/mL limit.
Lot-to-lot accelerator variation is held within ±0.05 mL/L by post-blend cyclic voltammetric stripping. Outside this range, fill height in 5 µm × 50 µm through-silicon via structures varies by up to 0.8 µm in supplier qualification runs on 300 mm tooling. The product is not a general-purpose bright acid copper bath; it should not be combined with commodity levelers or amine-based additives because amine-containing species form insoluble Cu-amine complexes that increase particle counts above the 50 counts/mL limit.
For tin-silver bumping, the main contaminant risk is not solely metal precipitates but changes in intermetallic growth. Copper in the bath above 25 ppb can co-deposit with tin and locally increase Cu-Sn intermetallic compound thickness. After reflow at 240–260 °C, this produces brittle regions that reduce ball shear force measured per JEDEC JESD22-B117. Iron contamination above 10 ppb in the tin-silver bath increases the formation of Fe-Sn intermetallics and raises voiding risk at the under-bump metallization interface. Lead contamination above 5 ppb disrupts the required Pb-free composition and may shift the liquidus outside the targeted reflow window. The Electronic/EL Grade limits contaminant non-tin metals to ≤5 ppb per element and total non-tin metals to ≤25 ppb. Whisker risk is assessed after temperature cycling per JEDEC JESD22-A121A; baths with iron above 10 ppb have shown local whisker density increases of one order of magnitude in 1000 h at 50 °C/50% RH in supplier qualification data. Published multi-wafer lot performance data for this specific formulation is limited; the stated threshold is drawn from controlled bath spike tests on 300 mm bumping tools.
Redistribution layer plating with EL-Cu A300 is run in a single-wafer fountain plater with edge flow control. The current density is typically held at 3.0 A/dm² for 8–12 µm thick lines and spaces. The plating solution is maintained at 25 °C ± 0.5 °C, and the wafer is rotated at 150–300 rpm depending on pattern density. Plating thickness uniformity across a 300 mm wafer is specified at ≤3% one-sigma. For through-silicon via fill, the same chemistry is operated at 1.0–2.0 A/dm² initial nucleation followed by 3.0–4.5 A/dm² bulk fill; the low-current step reduces suppressor consumption and prevents bottom voids. The bath is monitored every 8 h by cyclic voltammetric stripping and ICP-MS; if accelerator response shifts by more than 10% from the fresh-bath baseline, a bleed-and-feed program is initiated before particle counts rise.
| Parameter | Method/Standard | Specification |
|---|---|---|
| Trace metals | ISO 17294-2 | ≤5 ppb per element |
| Particle count ≥ 0.5 µm | ISO 21501-4 | ≤50 counts/mL |
| Total organic carbon | ISO 8245 | ≤20 mg/L |
| Density | ISO 12185 | model range per certificate of analysis |
| Viscosity | ISO 3104 | model range per certificate of analysis |
| pH | ISO 10523 | model range per certificate of analysis |
| Conductivity | ISO 7888 | model range per certificate of analysis |
| Anions | ISO 10304-1 | chloride 50–80 mg/L for EL-Cu A300 |
Chloride is not a contaminant in acid copper damascene chemistry but a functional co-adsorbate that modulates suppressor coverage. In the EL-Cu A300 formulation, chloride is specified at 50–80 mg/L. At chloride concentrations below 20 mg/L, suppressor adsorption is weakened, and the polarization resistance measured by linear sweep voltammetry decreases by more than 30% at −0.3 V versus saturated calomel electrode. This produces conformal rather than bottom-up fill and leaves void seams in 5 µm × 50 µm through-silicon vias. Above 100 mg/L, chloride accelerates the oxidation of the accelerator and can generate insoluble silver chloride if the bath is contaminated with silver from a shared plumbing loop or a previous tin-silver process. The upper boundary is therefore an incompatibility limit as well as a specification limit: shared recirculation pumps, valves, or storage tanks that previously handled tin-silver plating solution must be passivated and chloride-rinsed before copper service. The product is supplied with chloride already adjusted; additional hydrochloric acid dosing is not required unless the certified value is below target after prolonged drag-out. Trace metal partitioning is also chloride-dependent. Iron and nickel form weak chloro-complexes that reduce their adsorption on the cathode, but their accumulation in the bath is still controlled by bleed-and-feed because ICP-MS detects total metals, not electroactive fractions. A bath with total iron of 25 ppb may show electroactive iron below 5 ppb, but the analytical limit remains the controlling specification.
