The main customers of 25% TMAH are the well-known TFT-LCD factories in Taiwan, and it is also the raw material of 2.38% developer used by semiconductor factories in Taiwan.
Tetramethyl Ammonium Hydroxide (TMAH) – Electronic Grade Developer: Overview and Key Properties
| Category | Details |
|---|
| Chemical Name | Tetramethyl Ammonium Hydroxide (TMAH) |
| Molecular Formula | C₄H₁₃NO |
| CAS Number | 75-59-2 |
| Appearance | Colorless to pale yellow liquid |
| Grade | Electronic Grade (High Purity ≥99.99%) |
Physical & Chemical Properties
| Property | Value |
|---|
| Concentration | 2.38–25% (Semiconductor Grade) |
| Density (25°C) | ~1.01 g/cm³ (2.38% solution) |
| pH (25% sol.) | ~13.5 (Strong base) |
| Boiling Point | Decomposes before boiling |
| Flash Point | Non-flammable |
Key Applications in Electronics
| Application | Function |
|---|
| Semiconductor Lithography | Positive photoresist developer (for I-line, KrF, ArF) |
| LCD Manufacturing | Etchant for indium tin oxide (ITO) |
| Wafer Cleaning | Removes organic residues |
| Electroplating | Additive for copper deposition |
Semiconductor-Grade Specifications
| Parameter | Typical Requirement |
|---|
| Purity | ≥99.99% (Metals <1 ppb) |
| Particle Count | <100 particles/mL (>0.2 µm) |
| Chloride (Cl⁻) | <10 ppb |
| Sodium (Na⁺) | <1 ppb |
Safety & Handling
| Parameter | Details |
|---|
| OSHA PEL | Not established (handle as corrosive) |
| Health Hazards | Severe skin/eye burns; neurotoxic at high exposure |
| Storage | Polyethylene bottles; avoid CO₂ absorption |
| First Aid | Immediate water flushing (15 min for skin/eyes) |
Comparison with Alternative Developers
| Developer | TMAH vs. Alternatives |
|---|
| KOH | Higher metal contamination, less controllable |
| Tetraethyl Ammonium Hydroxide | More expensive, slower development |
| Sodium Hydroxide | Unsuitable for semiconductors (ionic contamination) |
Process Conditions (Photoresist Development)
| Parameter | Typical Range |
|---|
| Concentration | 2.38–5% |
| Temperature | 20–23°C |
| Development Time | 30–90 sec (spin process) |
| Rinse | DI water |
Market & Supply Chain
| Aspect | Details |
|---|
| Global Demand | ~50.000 tons/year (25% sol. basis) |
| Price (25% sol.) | $15–30/kg (Electronic Grade) |
| Major Suppliers | Tama Chemicals, Sachem, Fujifilm, TOK |
Key Advantages and Limitations
| Advantages | Limitations |
|---|
| Ultra-high purity for nodes <10nm | Highly toxic (requires strict handling) |
| Excellent photoresist selectivity | Decomposes at ~130°C |
| Low metal contamination | Expensive purification process |
Summary
TMAH is the industry-standard developer for advanced semiconductor and LCD manufacturing due to its ultra-high purity, controllable development rate, and compatibility with modern photoresists. Despite its toxicity, no equally effective alternative exists for sub-10nm processes. Future trends focus on closed-loop recycling and lower-concentration formulations to reduce costs and hazards.
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