Phosphoric Acid (Electronic Grade)
H₃PO₄ · CAS 7664-38-2
Electronic grade phosphoric acid (85% w/w) for hot phosphoric acid (HPA) selective etching of silicon nitride (Si₃N₄) over silicon dioxide — the critical etch step in STI (shallow trench isolation) and DRAM capacitor formation. Extreme selectivity (Si₃N₄:SiO₂ > 50:1) at 155–165°C.
Molecular Weight
98.00 g/mol
Boiling Point
158 °C (85%)
Density
1.685 g/mL (85%)
Molecular Formula
Available Grades
Analytical Specification
Analytical Specification Table
All values represent maximum allowable limits unless noted ≥. A lot-specific Certificate of Analysis (CoA) with ICP-MS, LPC, and GC data is issued for every shipment. Full data packages available on request.
| Parameter | Test Method | Unit | G4 |
|---|---|---|---|
| Assay | Titration | % | 84.5–85.5 |
| Total Metals | ICP-MS | ppb ea. | ≤0.5 |
| Fe (Iron) | ICP-MS | ppb | ≤0.2 |
| Cl⁻ (Chloride) | IC | ppb | ≤50 |
| SO₄²⁻ (Sulfate) | IC | ppb | ≤100 |
★ G5 = SEMI C1 Tier D (6N grade). All metal values by ICP-MS. Particle counts by in-line LPC during ISO Class 3 fill. CoA available on request.
Grade Comparison
G1 → G5 Purity Scale
Select the grade that matches your process node and contamination budget. Every grade is available from PureTech with full lot CoA and ICP-MS data.
All grades tested by ICP-MS (28 elements), in-line LPC (ISO Class 3 fill), and Karl Fischer titration. G5 = SEMI C1 Tier D. Full CoA per lot. Request CoA template →
Application Areas
Where Phosphoric Acid Is Used
Semiconductor Process
- Hot phosphoric acid (HPA) Si₃N₄ selective etch
- STI nitride removal etch
- DRAM capacitor nitride etch
- Self-aligned contact (SAC) nitride etch
- Post-CMP Si₃N₄ clean
Laboratory & Analytical
- Buffer solution preparation
- mobile phase modifier (ion pair HPLC)
Industrial & Other
- PCB copper pre-treatment
- fertilizer production
- food acidulant (E338)
Battery & Energy Storage
Packaging & Supply
Available Container Formats
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Our application engineers respond with full CoA data, ICP-MS reports, and supply chain details within one business day.