Buffered Oxide Etch (BOE) NH4F/HF
CAS Number: 7664-39-3
Buffered Oxide Etch (BOE) is a mixture of ammonium fluoride (NH4F) and hydrofluoric acid (HF) that provides a stable, controlled etch rate for silicon dioxide. The ammonium fluoride buffer maintains a consistent pH and replenishes fluoride ions, resulting in more uniform and reproducible oxide etch rates compared to straight HF. Widely used in MEMS, CMOS, and display fab processes.
Technical Specifications
| appearance | Colorless clear liquid |
| purity (%) | ≥99.5 (assay of active components) |
| NH4F:HF ratio | 6:1 or 10:1 (by volume, customizable) |
| SiO2 etch rate | 100–1000 Å/min (ratio-dependent) |
| metallic impurities | ≤1 ppb each |
Applications
- Thermal and PECVD silicon dioxide etching
- MEMS sacrificial oxide release
- Contact hole and via opening in CMOS
- Photoresist-compatible wet etch processes
- Gate dielectric patterning in display TFT
Key Features
- Stable etch rate with minimal drift over bath lifetime
- Excellent photoresist compatibility with low undercut
- Available in standard 6:1 and 10:1 NH4F:HF ratios
- Ultra-high purity grade meets SEMI C12 specification
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CAS Number
7664-39-3
Category
Semiconductor Etching ChemicalsAvailability
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