Wet Etching Recipes
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Table of Wet Etching Recipes
Use the ↑ ↓ Arrows in the header row to sort the entire table by material, selectivity, etchant etc.
| Material | Etchant | Rate (nm/min) | Anisotropy | Selective to | Selectivity | Ref. | Notes | Confirmed By/Date |
|---|---|---|---|---|---|---|---|---|
| Photoresist, polymers/organics | H2SO4:H2O2 = 3:1 | typ. 5-10min etch for polymer residue | Cr, W, Au, Pt, Si, SiO2, SiN | Dangerous boiling hazard - see Piranha Solution
section below. Etches Ti |
Demis D. John, 2017 | |||
| InP | H3PO4:HCl = 3:1 | ~1000 | Highly | InGaAsP | High | Lamponi (p.102) | ||
| InGaAsP | To Be Added | InP | High | |||||
| InP | H3PO4:HCl = 3:1 | ~1000 | Highly | InGaAs | High | Lamponi (p.102) | ||
| InP | HCl:H2O = 3:1 | ~5000 | InGaAs
~200nm stop-etch |
High | Bubbles while etching | |||
| InGaAs | H2SO4:H2O2:H2O = 1:1:10 | ~600 | InP | High | Exothermic, may reduce selectivity if hot | |||
| GaAs | NH4OH:H2O2 = 1:30 | - | AlGaAs,
Al > 80% ~200nm stop-etch |
High | Garrett Cole | |||
| AlGaAs,
Al ≥80% |
HF:H2O = 1:20 | - | GaAs | High | Garrett Cole | |||
| Oxide of InP | NH4OH:H2O = 1:10 | 1min to remove | InP | unknown | Ning Cao | |||
| Oxide of GaAs | HCl:H2O = 1:10 | 1min to remove | GaAs | unknown | Demis D. John | |||
| Al2O3 (ALD Plasma 300C) | Developer: 300MIF | ~1.6 | None | Most non-Al Materials. | High | Measured in-house | Rate slows with time. | JTB |
| Al2O3 (ALD Plasma 300C) | Developer: 400K | ~2.2 | None | Most non-Al Materials. | High | Measured in-house | Rate slows with time. | JTB |
| Al2O3 (ALD Plasma 300C) | Developer: 400K (1:4) | ~1.6 | None | Most non-Al Materials. | High | Measured in-house | Rate slows with time. | JTB |
| Al2O3 (ALD Plasma 300C) | NH4OH:H2O2:H2O (1:2:50) | ~<0.5 | Measured in-house | Rate slows with time | JTB | |||
| Al2O3 (IBD) | HF ("Buffered HF Improved", Transene) | ~170 | None | Photoresist | High | Measured in-house | May need to increase adhesion with thin SiO2 layer, and 100°C baked HMDS. | Biljana Stamenic,
2017-12 |
| Al2O3 (IBD) | Developer: 726 MiF | 3.5 | None | Most non-Al Materials. | High | Measured in-house | Demis D. John,
2017-11 | |
| Al2O3 (AJA#4) | Developer: 300 MiF | 4.30 | None | Most non-Al Materials. | High | Measured in-house | Demis D. John
2018-02 | |
| SiO2 (PECVD #1) | HF ("Buffered HF Improved", Transene) | ~550 | None | Photoresist | High | Measured in-house | May need to increase adhesion with 100°C baked HMDS. | Biljana Stamenic
2023 |
| SiO2 (PECVD #2) | HF ("Buffered HF Improved", Transene) | ~680 | None | Photoresist | High | Measured in-house | May need to increase adhesion with 100°C baked HMDS. | Biljana Stamenic
2023 |
| SiO2 (IBD) | HF ("Buffered HF Improved", Transene) | ~260 | None | Photoresist | High | Measured in-house | Biljana Stamenic
2023 | |
| Si3N4 (PECVD#1) | HF ("Buffered HF Improved", Transene) | ~120 | None | Photoresist | High | Measured in-house | Biljana Stamenic
2023 | |
| Si3N4 (PECVD#2) | HF ("Buffered HF Improved", Transene) | ~35 | None | Photoresist | High | Measured in-house | Biljana Stamenic
2023 | |
| Si3N4 Low-Stress (PECVD#2) | HF ("Buffered HF Improved", Transene) | ~30 | None | Photoresist | High | Measured in-house | Biljana Stamenic
2023 | |
| Si3N4 (IBD) | HF ("Buffered HF Improved", Transene) | ~5 | None | Photoresist | High | Measured in-house | Biljana Stamenic
2023 | |
| Ta2O5 (IBD) | HF ("Buffered HF Improved", Transene) | 0.07 | None | Photoresist | High | Measured in-house | Biljana Stamenic
2023 | |
| TiO2 (IBD) | HF ("Buffered HF Improved", Transene) | 1.0–2.0 | None | Photoresist | High | Measured in-house | Biljana Stamenic
2014-12 | |
| Si (<100> crystalline) | KOH (45%) @ 87°C | ~730 | High, Crystallographic, ~55° | Low-Stress Si3N4 - either PECVD #2 or Commercial LPCVD Si3N4
Other Si3N4 also OK. |
LS-SiN: High
PR etches quickly, SiO2 etches slowly. |
Measured In-House
- Search online. |
Use the Covered, Heated vertical bath (Dedi cated bath in Bay 4). Slight Bubbler. | Brian Thibeault
2017 |
| Material | Etchant | Rate (nm/min) | Anisotropy | Selective to | Selectivity | Ref. | Notes | Confirmed By/Date |
Wet Etching References
- Etch rates for Micromachining Processing (IEEE Jnl. MEMS, 1996) - includes tables of etch rates of numerous metals vs. various wet and dry etchants.
- Etch rates for micromachining-Part II (IEEE Jnl. MEMS, 2003) - expanded tables containing resists, dielectrics, metals and semiconductors vs. many wet etch chemicals.
- Guide to references on III±V semiconductor chemical etching - exhaustive list of wet etchants for etching various semiconductors, including selective etches.
- Transene's Chemical Compatibility Chart provides a useful quick-reference for which Transene etchants attack which materials.
- As a side-note, Transene provides many pre-mixed solutions that you can order, saving you the time and uncertainty of measuring/mixing such chemicals yourself. Make sure you check with us before ordering so we know how to handle the chemical before it arrives.
Compound Semiconductor Etching
Guide to references on III±V semiconductor chemical etching
Please add any confirmed etches from this reference to the The Master Table of Wet Etching (Include All Materials).
Metal Etching
- Selective Wet Etch of Cr over Ta using Cr Etchant
- Wet Etch of ITO using Heated, Diluted HCl Solution
Silicon etching
Etch rates for micromachining processing
Etch rates for micromachining processing-part II
Please add any confirmed etches from this reference to the The Master Table of Wet Etching (Include All Materials).
Organic removal
Piranha Solution
- Careful! Read about how to prepare and handle this safely:
- MIT's Piranha Solution safety document
- Harvard EHS's Handling Document
- Used for etching away Photoresist residues after dry etching.
PureStrip (Transene)
- Heat to @ 70°C
- Vertical heated bath on Wafer Toxic-Corrosive bench in Bay 4
- After a few days heated, it loses potency - must drain + replenish with fresh solution.
- ~30-90min will remove stubborn, microscopic PR residues from dry etching.
Gold Plating Bench (Technic SEMCON 1000)
Standard plating recipes are described and taught during the equipment training for this tool.
Electroplating first requires a Gold seed layer to be present on all surfaces to be plated. Common ways to produce this are to:
- Sputter-coat a thin (~10nm) Au layer on all surfaces of the wafer, being careful to consider shadowing effects during the dep (eg. in high-aspect ratio trenches).
- Perform photolithography to protect (and prevent plating) in desired areas - areas with no photoresist will be plated.
- Perform the electroplating on the Technic SemCon, contacting the seed layer with electrodes and executing the program for the desired current/time to achieve the plating thickness (typically microns).
- Strip the photoresist using standard solvents.
- Use the Oxford Ion Mill to blanket etch the 10nm seed layer all over the wafer (the 10nm removed from the plated regions will be negligible).
Chemi-Mechanical Polishing (CMP)
To Be Added
Mechanical Polishing (Allied)
To Be Added