Wet Chemical Etching of Metals and Semiconductors
A comprehensive list of etchants for 44 different metals, semiconductors and cleanroom materials. Some etch rates are given. The ratios are volume ratios unless other units are specified.
Aluminum
| Concentrations | Etchants | Rate (angstroms/sec) | Temperature/Other |
|---|---|---|---|
| 1 : 1 | H2O : HF | ||
| 1 : 1 : 1 | HCl : HNO3 : H2O | ||
| dilute or concentrated | HCl | ||
| H3PO4 : HNO3 : HAc | |||
| 19 : 1 : 1 : 2 | H3PO4 : HAc : HNO3 : H2O | 40 | |
| 3 : 1 : 3 : 1 | H3PO4 : HAc : HNO3 : H2O | 8.7 @ >RT | @ 40 C <4 min/micron |
| 4 : 4 : 1 : 1 | H3PO4 : HAc : HNO3 : H2O | 5.6 | |
| 15 : 0 : 1 : 1-4 | H3PO4 : HAc : HNO3 : H2O | 1500 | 40 C |
| 8 : 1 : 1 | H3PO4 : H2O2 : H2O | 100 | @ 35C |
| 3 : 1 : 5 | H3PO4 : H2O : glycerin | ||
| 69 : 131 | HClO4 : HAc | ||
| 4 : 1 : 5 | HCl : FeCle : H2O | ||
| FeCl3 : H2O | 100 F | ||
| 10% | K3Fe(CN)6 | 100 | |
| KOH : K3Fe(CN)6: K 2B4O7.4H2O | |||
| 2 : 3 : 12 | KMnO4 : NaOH : H2O | ||
| 1 : 1 : 3 | NH4OH : H2O2 : H2O | ||
| 20% | NH4SO4 | ||
| dilute or concetrated | NaOH | ||
| 8-10% | KOH | ||
| CCl4 | boiling | ||
| 10% | Br2 : MeOH | warm |
Aluminum Gallium Arsenide
| Concentrations | Etchants | Rate (angstroms/sec) | Temperature/Other |
|---|---|---|---|
| 1 : 1 : 30 | H2SO4 : H2O2 | 60 angstroms/sec | |
| 8 : 3 : 400 | NH3 : H2O2 : H2O | 25 angstroms/sec | |
| 1 : 1 : 10 | HF : H2O2 : H2O | 80 angstroms/sec |
Aluminum Trioxide / Alumina / Sapphire
| Concentrations | Etchants | Rate (angstroms/sec) | Temperature/Other |
|---|---|---|---|
| 1 : 1 : 3 | NH4OH : H2O2 : H2O | 80 C | |
| 10% | Br2 : MeOH | ||
| 7ml : 4g | H3PO : Cr2O3 |
Antimony
| Concentrations | Etchants | Rate (angstroms/sec) | Temperature/Other |
|---|---|---|---|
| 1 : 1 : 1 | HCl : HNO3 : H2O | ||
| 90 : 10 : 1 | H2O : HNO3 : HF | ||
| 3 : 3 : 1 : 1 | H3PO4 : HNO3 : CH3COOH : H2O | 3min/1000A | 50C |
Bismuth
| Concentrations | Etchants | Rate (angstroms/sec) | Temperature/Other |
|---|---|---|---|
| 10 : 1 | H2O : HCl |
Brass
| Concentrations | Etchants | Rate (angstroms/sec) | Temperature/Other |
|---|---|---|---|
| FeCl3 | |||
| 20% | NHSO5 |
Bronze
| Concentrations | Etchants | Rate (angstroms/sec) | Temperature/Other |
|---|---|---|---|
| 1% | CrO3 |
Carbon
| Concentrations | Etchants | Rate (angstroms/sec) | Temperature/Other |
|---|---|---|---|
| H3PO4 : CrO3 : NaCN | |||
| 50% | KOH (or NaOH) | boiling | |
| concentrated | HNO3 | ||
| concentrated | H2SO4 | ||
| 3 : 1 | H2SO4 : H2O2 |
Chromium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 2 : 3 : 12 | KMnO4 : NaOH : H2O | ||
| 3 : 1 | H2O : H2O2 | ||
| concentrated and dilute | HCl | ||
| 3 : 1 | HCl : H2O2 | ||
| 2 : 1 | FeCl : HCl | ||
| Cyantek CR-7s (Perchloric based) | 7 min/micron (24A/s new) | ||
| 1 : 1 | HCl : glycerine | 12min/micron after depassivation | |
| 1 : 3 | [50gNaOH+100mlH2O] : [30g K3Fe(CN)6+100mlH2O] | 1hr/micron |
Cobalt
| Concentrations | Etchants | Rate (angstroms/sec) | Temperature/Other |
|---|---|---|---|
| 1 : 1 | H2O : HNO3 | ||
| 3 : 1 | HCl : H2O2 |
Copper
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 30% | FeCl3 saturated solution | ||
| 20% | KCN | ||
| 1 : 5 | H2O : HNO3 | ||
| concentrated and dilute | HNO3 | ||
| 1 : 1 | NH4OH : H2O2 | ||
| 1 : 20 | HNO3 : H2O2 | ||
| 4 : 1 | NH3 : H2O2 | ||
| 1 : 1 : 1 | H3PO4 : HNO3 : HAc | ||
| 5ml : 5ml : 4g : 1 : 90ml | HNO3 : H2SO4 : CrO3 : NH4Cl : H2O | ||
| 4 : 1 : 5 | HCL : FeCl3 : H2O |
Epoxies
| Concentrations | Etchants | Rate (angstroms/sec) | Temperature/Other |
|---|---|---|---|
| 5 : 1 | NH4OH : H2O2 | 120 C | |
| Gold Epoxy | |||
| 3 : 1 : 10 | HNO3 : HCl : H2O | ||
| Silver Epoxy | |||
| 1 : 3 | HF : HNO3 | ||
| Aluminum Epoxy | |||
| H2SO4 | hot | ||
| SU8 cured | |||
| 3 : 1 | H2SO4 : H2O2 | hot |
Gallium Arsenide
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1.5%-7.5% | Br2 in CH3OH | ||
| 1 : 1 | NH4OH : H2O2 | ||
| 20 : 7 : 973 | NH4OH : H2O2 : H2O | ||
| 40 : 1 : 40 | H3PO4 : H2O2 : H2O | ||
| 3 : 1 : 50 | H3PO4 : H2O2 : H2O | ||
| 33-66% | HNO3 | red fuming etches more rapidly than white fuming | |
| 1 : 1 | HF : HNO3 | ||
| 1 : 1 | H2SO4 : H2O2 | ||
| 1 : 1 : 30 | H2SO4 : H2O2 : H2O | 60 angstroms/sec | |
| 8 : 3 : 400 | NH3 : H2O2 : H2O | 30 angstroms/sec | isotropic |
| 1 : 1 : 10 | HF : H2O2 : H2O | 80 angstroms/sec |
Germanium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| HF : HNO3 : H2O | |||
| 1 : 1 : 1 | HF : HNO3 : HAc | ||
| 7 : 1 : | HF : HNO3 : glycerin | 35c 75-100 microns/hour, 100C 775microns/hour | |
| pH > 6 | KF | ||
| 1 : 25 | NH3OH : H2O2 | 1000 angstrom/min |
Gold
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 3 : 1 | Aqua Regia HCl : HNO3 10-15 | microns/min RT, 25-50 microns/min | 35 C |
| 3 : 10-20% | Chrome Regia HCl : CrO3 | ||
| H2SeO4 | etch is slow | Temp should be hot | |
| KCN in H2O | good for stripping gold from alumina, quartz, sapphire substrates, semiconductor wafers and metal parts | ||
| 4g : 2g : 10ml | KI : I2 : H2O | 280 nm/min | Hot (70C) |
| 1 : 2 : 3 | HF : HAc : HNO3 | ||
| 30 : 30 : 50 : 0.6 | HF : HNO3 : HAc : Br2 | ||
| NaCN : H2O2 | |||
| 7g : 25g : 100ml | KI : Br2 : H2O | ||
| 9g : 1g : 50ml | KBr : Br2 : H2O | 800 nm/min | |
| 9g : 1g : 50ml | NaBr : Br2 : H2O | 400nm/min | |
| 400g : 100g : 400ml | I2 : KI : H2O | 1270A/sec | 55C |
| 1 : 2 : 10 | I2 : KI : H2O | ||
| 4g : 1g : 40ml | Au mask etch KI : I2 : H2O | 1min/micron |
Hafnium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 20 : 1 : 1 | H2O : HF : H2O2 |
Indium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 3 : 1 | Aqua Regia HCl : HNO3 | hot | |
| HCl | fast | boiling | |
| IPA | hot | ||
| EOH | hot | ||
| MeOH | hot |
Rare Earth Indium Etchants Br2 : MeOH
Indium Gallium Arsenide
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 : 20 | H2SO4 : H2O2 : H2O | 30 angstroms/sec |
Indium Gallium Phosphide
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| concentrated | HCl | fast |
Indium Phosphide
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | HCl : H3PO4 | fast |
Indium Phosphide Oxide
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| NH4OH |
Indium Tin Oxide
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | HCl : H2O | 8 angstroms/sec | |
| 1 : 1 : 10 | HF : H2O2 : H2O | 125 angstroms/sec |
Iridium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 3 : 1 | Aqua Regia HCl : HNO3 | hot |
Iron
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | H2O : HCL | ||
| 1 : 1 | H2O : HNO3 | ||
| 1 : 2 : 10 | I2 : KI : H2O |
Lead
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | HAc : H2O2 |
Magnesium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 10ml : 1g | H2O : NaOH | followed by | |
| 5ml : 1g | H2O : CrO3 |
Molybendum
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | HCl : H2O2 |
Nickel
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 : 1 | HNO3 : HAc : Acetone | ||
| 1 : 1 | HF : HNO3 | ||
| 30% | FeCl3 | ||
| 3 : 1 : 5 : 1 | HNO3 : H2SO4 : HAc : H2O | 10 microns/min | 85 C |
| 3 : 7 | HNO3 : H2O | ||
| 1 : 1 | HNO3 : HAc | ||
| 10% g/ml | Ce(NH4)2(NO3)6 : H2O | ||
| concentrated | HF | slow etchant | |
| H3PO4 | slow etchant | ||
| HNO3 | rapid etchant | ||
| HF : HNO3 | etch rate determined by ratio, the greater the amount of HF the slower the reaction | ||
| 4 : 1 | HCl : HNO3 | increase HNO3 concentration increases etch rate | |
| 30% | FeCl3 | ||
| 5g : 1ml : 150ml | 2NH4NO3.Ce(NO3)3.4(H2O) : HNO3 : H2O | decreasing HNO3 amount increases the etch rate. | |
| 3 : 3 : 1 : 1 | H3PO4 : HNO3 : CH3COOH : H2O | ~15min/micron | RT with air exposure every 15 seconds |
Niobium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | HF : HNO3 |
Palladium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 3 : 1 | HCl : HNO3 (Aqua Regia) | Hot |
Photoresist (AZ Type)
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| General Polymer | |||
| Acetone | |||
| 5 : 1 | NH4OH : H2O2 | 120 C | |
| 5 : 1 | H2SO4 : H2O2 | ||
| H2SO4 : (NH4)2S2O8 |
Platinum
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 3 : 1 | HCl : HNO3 (Aqua Regia) | Hot | |
| Molten Sulfur |
Polymer
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 5 : 1 | NH4OH : H2O2 | 120 C | |
| 3 : 1 | H2SO4 : H2O2 | ||
| 1 : 1 | HF : H2O | ||
| 1 : 1 | HF : HNO3 | ||
| 1 : 1 | Sodium Carbonate | boiling | |
| conc | HF |
Rhenium, Rhodium, and Ruthenium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 3 : 1 | HCl : HNO3 (Aqua Regia) | Hot |
Silicon
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 64 : 3 : 33 | HNO3 : NH4F : H2O | 100 angstroms/s | |
| 61 : 11 : 28 | ethylenediamine : C6H4(OH)2 : H2O | 78 angstroms/s | |
| 108ml : 350g : 1000ml | HF : NH4F : H2O | slow - 0.5 angstroms/min | |
| 1 : 1 : 50 | HF : HNO3 : H2O | slow etch | |
| KCl dissolved in H2O | |||
| KOH : H2O : Br2/I2 | |||
| KOH | see section on KOH etching | ||
| 1 : 1 : 1.4 : 0.15% : 0.24% | HF : HNO3 : HAc : I2 : triton | ||
| 1 : 6 : 3 | HF : HNO3 : HAc and 0.19 g NaI per 100 ml solution |
||
| 1 : 4 | Iodine Etch : HAc | ||
| 0.010 N | NaI | ||
| NaOH | |||
| HF : HNO3 | |||
| 1 : 1 : 1 | HF : HNO3 : H2O |
Silicon Dioxide / Quartz / Glass
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| BOE 1 : 5 : 5 | HF : NH4HF : H2O | 20 angstroms/sec | |
| HF : HNO3 | |||
| 3 : 2 : 60 | HF : HNO3 : H2O | 2.5 angstroms/sec | Room Temp |
| BHF 1 : 10, 1 : 100, 1 : 20 | HF : NH4F(sat) | ||
| 3ml : 15g : 22ml | HF : NH4F : H2O | ||
| Secco etch 2 : 1 | HF : 1.5M K2Cr2O7 | ||
| 5 : 1 | NH4.HF : NaF/L (in grams) | ||
| 1g : 1ml : 10ml : 10ml | NH4F.HF : HF : H2O : glycerin | ||
| HF | Hot | ||
| 1 : 1, 1 : 15, 1 : 100 | HF : H2O | ||
| 5 : 43, 1 : 6 | HF : NH4F(40%) | ||
| NaCO3 | 296 microns/h | 100 C | |
| 5% | NaOH | 3.8 mm/h | 100 C |
| 5% | HCl | 12.7 microns/day | 95 C |
| KOH | see KOH etching of silicon dioxide |
Silicon Nitride
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 60 or 1 : 20 | HF : H2O | 1000-2000 A/min | |
| BHF 1 : 2 : 2 | HF : NH4F : H2O | slow attack – but faster for silicon oxynitride | |
| 1 : 5 or 1 : 9 | HF : NH4F (40%) | 0.01-0.02 microns/second | |
| 3 : 25 | HF : NH4F.HF(sat) | ||
| 50ml : 50g : 100ml : 50ml | HF : NH4F.HF : H2O : glycerin | glycerin provides more uniform removal | |
| BOE | HF : NH4F : H2O | ||
| 18g : 5g : 100ml | NaOH : KHC8H4O4 : H2O | 160 A/min, better with silicon oxynitride | boiling |
| 9g : 25ml | NaOH : H2O | 160A/min | boiling |
| 18g : 5g : 100ml | NaOH : (NH4)2S2O8 : H2O | 160 A/min | boiling |
| A) 5g : 100ml | NH4F.HF : H2O; | ||
| B)1g : 50ml : 50ml | I2 : H2O : glycerin | 180 A/min | RT – mix A and B 1 : 1 when ready to use. |
Silver
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | NH4OH : H2O2 | ||
| 3 : 3 : 23 : 1 | H3PO4 : HNO3 : CH3COOH : H2O | ~10min/100A | |
| 1 : 1 : 4 | NH4OH : H2O2 : CH3OH | .36micron/min resist | |
| 1 : 1 : 1 | HCl : HNO3 : H2O | ||
| 1-8 : 1 | HNO3 : H2O | ||
| 1 M | HNO3 + light |
Stainless Steel
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | HF : HNO3 |
Tantalum
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | HF : HNO3 |
Tin
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | HF : HCL | ||
| 1 : 1 | HF : HNO3 | ||
| 1 : 1 | HF : H2O | ||
| 2 : 7 | HClO4 : HAc |
Titanium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 50 : 1 : 1 | H2O : HF : HNO3 | ||
| 20 : 1 : 1 | H2O : HF : H2O2 | ||
| RCA-1 5 : 1 : 1 | H2O : 27% NH4OH : 30% H2O2 | ~100 min/micron | |
| x%Br2 : ethyl acetate | HOT | ||
| x%I2 : MeOH | HOT | ||
| HF : CuSO4 | |||
| 1 : 2 | NH4OH : H2O2 | ||
| 1 : 4 : 5 | HF : HNO3 : H2O | 18 microns/min | |
| 1 : 2 : 7, 1 : 5 : 4, 1 : 1 : 50 | HF : HNO3 : H2O | ||
| any concentration | COOHCOOH : H2O | ||
| 1 : 1 : 20 | HF : H2O2 : HNO3 | ||
| 1 : 9 | HF : H2O | 12 A/min | |
| HF : HCL : H2O | |||
| conc | HCL | ||
| conc | %KOH | ||
| conc | %NaOH | ||
| 20% | H2SO4 | 1 micron/min | |
| CCl3COOC2H5 | |||
| 25% | HCOOH | ||
| 20% | H3PO4 | ||
| HF |
Tungsten
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | HF : HNO3 | thin films | |
| 3 : 7 | HF : HNO3 | ||
| 4 : 1 | HF : HNO3 | rapid attack | |
| 1 : 2 | NH4OH : H2O2 | thin films good for etching tungsten from stainless steel, glass, copper and ceramics. Will etch titanium as well. | |
| 305g : 44.5g : 1000ml | K3Fe(CN)6 : NaOH : H2O | rapid etch | |
| HCl | slow etch (dilute or concentrated) | ||
| HNO3 | very slow etch (dilute or concentrated) | ||
| H2SO4 | slow etch (dilute or concentrated) | ||
| HF | slow etch (dilute or concentrated) | ||
| H2O2 | |||
| 1 : 2 | NH4OH : H2O2 | ||
| 4 : 4 : 3 | HF : HNO3 : HAc | ||
| CBrF3 RIE etch | |||
| 305g : 44.5g : 1000ml | K3Fe(CN)6 : NaOH : H2O | very rapid etch | |
| 3 : 1 | HCL : HNO3 (Aqua Regia) | slow attack | when hot or warm |
| Alkali with oxidizers (KNO3 and PbO2) | rapid etch |
Vanadium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | H2O : HNO3 | ||
| 1 : 1 | HF : HNO3 |
Zinc
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 1 | HCl : H2O | ||
| 1 : 1 | HNO3 : H2O |
Zinc Oxide
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 1 : 60 | HCl : H2O | 1.9 microns/min | |
| 1 : 200 | HCl : H2O | 0.9 microns/min | |
| 1 : 500 | HCl : H2O | 0.4 microns/min | |
| 1 : 900 | HCl : H2O | 0.2 microns/min | |
| 1 : 100 | HNO3 : H2O | 0.9 microns/min | |
| 1 : 7 | BOE | .06 microns/min | |
| 1 : 7 | BOE | .06 microns/min | |
| 1 : 1 : 30 | H3PO4 : C6H8O7 : H2O | 2.2 microns/min | |
| 1 : 5 : 60 | H3PO4 : C6H8O7 : H2O | 1.8 microns/min | |
| 1 : 1 : 80 | H3PO4 : C6H8O7 : H2O | 1.4 microns/min | |
| 1 : 1 : 150 | H3PO4 : C6H8O7 : H2O | 1 micron/min | |
| 1 : 1 : 200 | H3PO4 : C6H8O7 : H2O | 0.8 microns/min | |
| 1 : 2 : 300 | H3PO4 : C6H8O7 : H2O | 0.65 microns/min |
Zirconium
| Concentrations | Etchants | Rate | Temperature/Other |
|---|---|---|---|
| 50 : 1 : 1 | H2O : HF : HNO3 | ||
| 20 : 1 : 1 | H2O : HF : H2O2 |