What is semiconductor-grade hydrofluoric acid 49%?
Aqueous hydrofluoric acid (CAS 7664-39-3) at 48.8 – 49.2 wt % HF, specified in semiconductor grades 1, 2 and 3. The grades differ in color (≤ 10 or ≤ 5 APHA), H2SiF6 (≤ 5 or ≤ 1 ppm), chloride, nitrate and phosphate (≤ 20 or ≤ 10 ppb), sulfate (≤ 50 or ≤ 10 ppb), each of 34 listed trace metals (≤ 1, ≤ 0.1 or ≤ 0.01 ppb) and particle counts per mL. EPA states that the ultra-high purity aqueous HF used in semiconductor chip manufacture is typically purchased in its most concentrated form of 49 percent but is typically used in much more dilute solutions of 1 to 10 percent.
- ▸ Semiconductor wet processing: EPA states that the ultra-high purity aqueous HF used in semiconductor chip manufacture is typically purchased in its most concentrated form of 49 percent but is typically used in much more dilute solutions of 1 to 10 percent.
- ▸ Buffered oxide etch: NH4F:HF buffered oxide etch is used routinely in electronics manufacturing because it gives more stable etch rates than plain HF and has comparatively lower vapor pressure. Commercial NH4F:HF buffered oxide etch ratios (for example 6:1 or 20:1) are normally stated as the volume ratio of 40 wt% NH4F solution to 49 wt% HF.
- ▸ Native-oxide removal: Aqueous fluoride etching (HF and NH4F:HF) has been used on silica glass for glass cleaning, native-oxide removal in silicon wafer processing, and etching gratings and other structures on glass.
- ▸ Technical Data Sheet: Hydrofluoric Acid 49% semiconductor grades 1, 2 and 3 (TDS V1.0, issued 2026-09-30) PDF · TDS
The data sheet states specification limits by grade; it gives no typical values and no test methods. Binding specifications are those stated on the lot-specific Certificate of Analysis and in the sales contract. Refer to the Safety Data Sheet before handling.
A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.
Request SDS →Hydrofluoric Acid 49% semiconductor grade (CAS 7664-39-3) is hydrofluoric acid specified for semiconductor use in grades 1, 2 and 3, with limits on anions, 34 trace metals and particles. Download the technical data sheet (PDF) or see the hydrofluoric acid product page.
Frequently Asked Questions
What grades does the data sheet specify?
Semiconductor grades 1, 2 and 3. All three hold HF at 48.8 – 49.2 wt %; they differ in color, H2SiF6, anion, trace-metal and particle limits. Grade 3 has the tightest trace-metal limits (≤ 0.01 ppb for each listed element) and is specified on a finer particle-size basis (≥ 0.05 to ≥ 0.5 micron).
Which SEMI C28 grade is this?
The data sheet specifies semiconductor grades 1, 2 and 3 by its own limits and does not state a SEMI C28 grade designation. SEMI C28 (Specification and Guide for Hydrofluoric Acid) standardizes requirements for hydrofluoric acid used in the semiconductor industry and supporting test procedures. Compare the limits on the data sheet with the grade your process specifies.
What trace-metal limits apply?
Each of 34 listed elements (Al, Sb, As, Ba, Be, Bi, B, Cd, Ca, Cr, Co, Cu, Ga, Ge, Au, Fe, Pb, Li, Mg, Mn, Mo, Ni, Nb, K, Ag, Na, Sr, Ta, Tl, Sn, Ti, V, Zn, Zr) is limited to ≤ 1 ppb in grade 1, ≤ 0.1 ppb in grade 2 and ≤ 0.01 ppb in grade 3.
What particle limits apply?
Grades 1 and 2, per mL: ≤ 100 at ≥ 0.2 micron; ≤ 20 at ≥ 0.3 micron; ≤ 5 at ≥ 0.5 micron; ≤ 1 at ≥ 1.0 micron. Grade 3, per mL: ≤ 250 at ≥ 0.05 micron; ≤ 80 at ≥ 0.1 micron; ≤ 40 at ≥ 0.2 micron; ≤ 1 at ≥ 0.5 micron. Grade 3 is specified on a different particle size basis than grades 1 and 2.
What anion and H2SiF6 limits apply?
H2SiF6 Grade 1: ≤ 5, Grade 2: ≤ 1, Grade 3: ≤ 1 ppm; Cl Grade 1: ≤ 20, Grade 2: ≤ 10, Grade 3: ≤ 10 ppb; NO3 Grade 1: ≤ 20, Grade 2: ≤ 10, Grade 3: ≤ 10 ppb; PO4 Grade 1: ≤ 20, Grade 2: ≤ 10, Grade 3: ≤ 10 ppb; SO4 Grade 1: ≤ 50, Grade 2: ≤ 10, Grade 3: ≤ 10 ppb.
How is it packaged?
235 net kg new poly drums. Drums must have proper hazardous markings, UN# and placards. Shelf life: 1 year. Consult SDS for storage and disposal.
Does the data sheet give typical values or test methods?
No. It states specification limits by grade only. Binding specifications are those stated on the lot-specific Certificate of Analysis and in the sales contract. Refer to the Safety Data Sheet before handling.
Is 49% HF used at full strength in fabs?
EPA states that the ultra-high purity aqueous HF used in semiconductor chip manufacture is typically purchased in its most concentrated form of 49 percent but is typically used in much more dilute solutions of 1 to 10 percent.
Which container materials are compatible with HF?
HF-based etching solutions should be handled in polypropylene, HDPE, PTFE, PVDF or similar plastic containers and tools, not glass, which HF attacks. High density polyethylene resists hydrofluoric acid solutions up to 70% at temperatures up to 60 °C; polypropylene and PVC are not recommended as a single construction material without resin/fibre reinforcement (glass fibre to be avoided).
Packaging for this grade: 235 net kg new poly drums. Drums must have proper hazardous markings, UN# and placards. Shelf life: 1 year. Consult SDS for storage and disposal.
Compatible materials. HF-based etching solutions should be handled in polypropylene, HDPE, PTFE, PVDF or similar plastic containers and tools, not glass, which HF attacks. (IEEE Journal of Microelectromechanical Systems, 1996.) High density polyethylene resists hydrofluoric acid solutions up to 70% at temperatures up to 60 °C; polypropylene and PVC are not recommended as a single construction material without resin/fibre reinforcement (glass fibre to be avoided). PVDF has good resistance to AHF/HF up to at least 90 °C depending on grade; FEP, PFA and ETFE are used for their resistance and lower permeation rate than PTFE. (Industry materials-of-construction guidance.)
Materials to avoid. Glass and the reactive metals titanium, zirconium and tantalum are readily attacked by hydrofluoric acid, and any alloy that depends on a passive oxide film for corrosion protection performs poorly because HF dissolves most oxides. Ceramics, glass, bricks and mineral fibres containing silica are strongly attacked by AHF/HF even when dilute and at low temperature and must not be used; silicon carbide is usable across the concentration range only if it contains no free silicon. (Industry materials-of-construction guidance.)
Refer to the Safety Data Sheet before handling, storage, transport or disposal.