Tetramethylammonium Hydroxide (TMAH)
(CH₃)₄NOH · CAS 75-59-2
Tetramethylammonium hydroxide (TMAH) is the universal photoresist developer for positive-tone resists in semiconductor lithography. The standard 2.38% w/w aqueous solution develops exposed positive chemically amplified resists at all lithography nodes. Also used as an anisotropic silicon etchant in MEMS fabrication.
Molecular Weight
91.15 g/mol
Boiling Point
> 100 °C
Density
1.02 g/mL (25%)
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 | G5 ★ |
|---|---|---|---|---|
| Assay (TMAH) | Titration | % | 2.35–2.40 | 2.37–2.39 |
| Total Metals | ICP-MS | ppb ea. | ≤0.5 | <0.1 |
| Na (Sodium) | ICP-MS | ppb | ≤1 | <0.1 |
| Cl⁻ (Chloride) | IC | ppb | ≤50 | ≤10 |
| Particles ≥0.2μm | LPC | ct/mL | ≤50 | ≤20 |
★ 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 Tetramethylammonium Hydroxide Is Used
Semiconductor Process
- Positive photoresist development (2.38% aqueous)
- KrF, ArF, EUV CAR photoresist developer
- Anisotropic silicon etching for MEMS (25% TMAH at 80°C)
- Aluminum etch at low concentration
- LCD array TFT photoresist development
- Post-develop rinse bath additive
Laboratory & Analytical
- Strong base for organic synthesis
- phase-transfer catalyst
Industrial & Other
- LCD TFT array photoresist development
- PCB solder mask development
Packaging & Supply
Available Container Formats
Related Products
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