on this page

Metal and Semiconductor Wet Etching

Aluminum

Concentrations Etchants Rate (Å/sec) Temp
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 @ 35 C
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:K2B4O7.4H2O
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

  1. 1:1:30 - H2SO4:H2O2 - 60 angstroms/sec
  2. 8:3:400 - NH3:H2O2:H2O - 25 angstroms/sec
  3. 1:1:10 - HF:H2O2:H2o - 80 angstroms/sec

Aluminum Trioxide / Alumina / Sapphire

  1. 1:1:3 - NH4OH:H2O2:H2O - 80 C
  2. 10% Br2:MeOH
  3. 7ml:4g - H3PO:Cr2O3

Antimony

  1. 1:1:1 - HCl:HNO3:H2O
  2. 90:10:1 - H2O:HNO3:HF
  3. 3:3:1:1 - H3PO4:HNO3:CH3COOH:H2O<<3min/1000A@50C

Bismuth

  1. 10:1 - H2O:HCl

Brass

  1. FeCl3
  2. 20% NHSO5

Bronze

  1. 1% CrO3

Carbon

  1. H3PO4:CrO3:NaCN
  2. 50% KOH (or NaOH) - boiling
  3. HNO3 concentrated
  4. H2SO4 concentrated
  5. 3:1 - H2SO4:H2O2

Chromium

  1. 2:3:12 KMnO4:NaOH:H2O
  2. 3:1 - H2O:H2O2
  3. HCl concentrated and dilute
  4. 3:1 - HCl:H2O2
  5. 2:1 - FeCl:HCl
  6. Cyantek CR-7s (Perchloric based) 7 min/micron (24A/s new)
  7. 1:1 - HCl:glycerine 12min/micron after depassivation
  8. 1:3 - [50gNaOH+100mlH2O]:[30g K3Fe(CN)6+100mlH2O] 1hr/micron

Cobalt

  1. 1:1 H2O:HNO3
  2. 3:1 HCl:H2O2

Copper

  1. 30% FeCl3 saturated solution
  2. 20% KCN
  3. 1:5 - H2O:HNO3
  4. HNO3 concentrated and dilute
  5. 1:1 - NH4OH:H2O2
  6. 1:20 - HNO3:H2O2
  7. 4:1 - NH3:H2O2
  8. 1:1:1 - H3PO4:HNO3:HAc
  9. 5ml:5ml:4g:1:90ml - HNO3:H2SO4:CrO3:NH4Cl:H2O
  10. 4:1:5 - HCL:FeCl3:H2O

Epoxies

  1. General Polymer Etch
  2. 5:1 - NH4OH:H2O2 - 120 C
  3. Gold Epoxy
  4. 3:1:10 HNO3:HCl:H2O
  5. Silver Epoxy
  6. 1:3 - HF:HNO3
  7. Aluminum Epoxy
  8. H2SO4 - hot
  9. SU8 cured
  10. 3:1 - H2SO4:H2O2 - hot

Gallium Arsenide

  1. 1.5%-7.5% - Br2 in CH3OH
  2. 1:1 - NH4OH:H2O2
  3. 20:7:973 - NH4OH:H2O2:H2O
  4. 40:1:40 - H3PO4:H2O2:H2O
  5. 3:1:50 - H3PO4:H2O2:H2O
  6. 33-66% - HNO3 - red fuming etches more rapidly than white fuming
  7. 1:1 - HF:HNO3
  8. 1:1 - H2SO4:H2O2
  9. 1:1:30 - H2SO4:H2O2 - 60 angstroms/sec
  10. 8:3:400 - NH3:H2O2:H2O - 30 angstroms/sec, isotropic
  11. 1:1:10 - HF:H2O2:H2o - 80 angstroms/sec

Germanium

  1. HF:HNO3:H2O
  2. 1:1:1 - HF:HNO3:HAc
  3. 7:1:x HF:HNO3:glycerin 35c 75-100 microns/hour, 100C 775microns/hour
  4. KF - pH > 6
  5. 1:25 NH3OH:H2O2 1000 angstrom/min

Gold

  1. Aqua Regia 3:1 - HCl:HNO3 10-15 microns/min RT, 25-50 microns/min 35 C
  2. Chrome Regia 3:10-20% HCl:CrO3
  3. H2SeO4 - Temp should be hot, etch is slow
  4. KCN in H20 - good for stripping gold from alumina, quartz, sapphire substrates, semiconductor wafers and metal parts
  5. 4g:2g:10ml - KI:I2:H2O Hot (70C) 280 nm/min
  6. 1:2:3 - HF:HAc:HNO3
  7. 30:30:50:0.6 - HF:HNO3:HAc:Br2
  8. NaCN:H2O2
  9. 7g:25:g:100ml - KI:Br2:H2O
  10. 9g:1g:50ml - KBr:Br2:H2O 800 nm/min
  11. 9g:1g:50ml - NaBr:Br2:H2O 400nm/min
  12. 400g:100g:400ml - I2:KI:H2O 55C 1270A/sec
  13. 1:2:10 - I2:KI:H2O
  14. Au mask etch 4g:1g:40ml - KI:I2:H2O 1min/micron

Hafnium

  1. 20:1:1 - H2O:HF:H2O2

Indium

  1. Aqua Regia 3:1 - HCl:HNO3 hot
  2. HCl boiling, fast
  3. IPA
  4. EOH
  5. MeOH
  6. Rare Earth Indium Etchants
      1. Br2:MeOH

Indium Gallium Arsenide

  1. 1:1:20 - H2SO4:H2O2:H2O - 30 angstroms/sec

Indium Gallium Phosphide

  1. conc HCl - fast

Indium Phosphide

  1. 1:1 - HCl:H3PO4

Indium Phosphide Oxide Etchants

  1. NH4OH

Indium Tin Oxide (ITO)

  1. 1:1 - HCl:H2O 8 angstroms/sec
  2. 1:1:10 - HF:H2O2:H2O 125 angstroms/sec

Iridium

  1. Aqua Regia 3:1 - HCl:HNO3 hot

Iron

  1. 1:1 - H2O:HCL
  2. 1:1 - H2O:HNO3
  3. 1:2:10 - I2:KI:H2O

Lead

  1. 1:1 - HAc:H2O2

Magnesium

  1. 10ml:1g - H2O:NaOH followed by 5ml:1g - H2O:CrO3

Molybendum

  1. 1:1 - HCl:H2O2

Nickel

  1. 1:1:1 - HNO3:HAc:Acetone
  2. 1:1 - HF:HNO3
  3. 30% FeCl3
  4. 3:1:5:1 - HNO3:H2SO4:HAc:H2O 85 C 10 microns/min
  5. 3:7 - HNO3:H2O
  6. 1:1 - HNO3:HAc
  7. 10% g/ml Ce(NH4)2(NO3)6:H20
  8. HF, concentrated - slow etchant
  9. H3PO4 - slow etchants
  10. HNO3 - rapid etchant
  11. HF:HNO3 - etch rate determined by ratio, the greater the amount of HF the slower the reaction
  12. 4:1 - HCl:HNO3 - increase HNO3 concentration increases etch rate
  13. 30% FeCl3
  14. 5g:1ml:150ml - 2NH4NO3.Ce(NO3)3.4(H2O):HNO3:H2O - decreasing HNO3 amount increases the etch rate
  15. 3:3:1:1 - H3PO4:HNO3:CH3COOH:H2O ~15min/micron @ RT with air exposure every 15 seconds

Niobium

  1. 1:1 - HF:HNO3

Palladium

  1. Aqua Regia 3:1 - HCl:HNO3 hot

Photoresist (AZ Type)

  1. General Polymer
  2. 5:1 - NH4OH:H2O2 - 120 C
  3. 5:1 - H2SO4:H2O2
  4. H2SO4:(NH4)2S2O8
  5. Acetone

Platinum

  1. Aqua Regia 3:1 - HCl:HNO3 Hot
  2. Molten Sulfur

Polymer

  1. 5:1 - NH4OH:H2O2 - 120 C
  2. 3:1 - H2SO4:H2O2

Polymer

  1. 1:1 - HF:H2O
  2. 1:1 - HF:HNO3
  3. Sodium Carbonate boiling
  4. HF conc

Rhenium, Rhodium, and Ruthenium

  1. Aqua Regia 3:1 - HCl:HNO3 - Hot

Silicon

  1. 64:3:33 - HNO3:NH4F:H2O 100 angstroms/s
  2. 61:11:28 - ethylenediamine:C6H4(OH)2:H2O 78 angstroms/s
  3. 108ml:350g:1000ml - HF:NH4F:H2O slow 0.5 angstroms/min
  4. 1:1:50 - HF:HNO3:H2O slow etch
  5. KCl dissolved in H2O
  6. KOH:H2O:Br2/I2
  7. KOH - see section on KOH etching of silicon
  8. 1:1:1.4:0.15%:0.24% - HF:HNO3:HAc:I2:triton
  9. 1:6:3 - HF:HNO3:HAc and 0.19 g NaI per 100 ml solution
  10. 1:4 - Iodine Etch:HAc
  11. 0.010 N NaI
  12. NaOH
  13. HF:HNO3
  14. 1:1:1 - HF:HNO3:H2O

Silicon Dioxide / Quartz / Glass

  1. BOE 1:5:5 HF:NH4HF:H2O 20 angstroms/s
  2. HF:HNO3
  3. 3:2:60 HF:HNO3:H20 2.5 angstroms/sec at RT
  4. BHF 1:10, 1:100, 1:20 HF:NH4F(sat)
    • 3ml:15g:22ml HF:NH4F:H2O
  5. Secco etch 2:1 HF:1.5M K2Cr2O7
  6. Secco etch 2:1 HF:1.5M K2Cr2O7
  7. 5:1 NH4.HF:NaF/L (in grams)
  8. 1g:1ml:10ml:10ml NH4F.HF:HF:H2O:glycerin
  9. HF - hot
  10. 1:1 1:15, 1:100 HF:H2O
  11. BOE HF:NH4F:H2O
  12. 1:6 BOE:H2O
  13. 5:43, 1:6 HF:NH4F(40%)
  14. NaCO3 100 C 8.8 mm/h
  15. 5% NaOH 100 C 150 mm/h
  16. 5% HCl 95 C 0.5mm/day
  17. KOH see KOH etching of silicon dioxide and silicon nitride

Silicon Nitride

  1. 1:60 or 1:20 HF:H2O 1000-2000 A/min
  2. BHF 1:2:2 HF:NH4F:H2O slow attack - but faster for silicon oxynitride
  3. 1:5 or 1:9 HF:NH4F (40%)0.01-0.02 microns/second
  4. 3:25 HF:NH4F.HF(sat)
  5. 50ml:50g:100ml:50ml HF:NH4F.HF:H2O:glycerin - glycerin provides more uniform removal
  6. BOE HF:NH4F:H2O
  7. 18g:5g:100ml NaOH:KHC8H4O4:H2O boiling 160 A/min, better with silicon oxynitride
  8. 9:g25ml NaOH:H20 - boiling 160A/min
  9. 18g:5g:100ml NaOH:(NH4)2S2O8:H2O - boiling 160 A/min
  10. A) 5g:100ml NH4F.HF:H2O B)1g:50ml:50ml I2:H2O:glycerin - mix A and B 1:1 when ready to use. RT 180 A/min

Silver

  1. 1:1 NH4OH:H2O2
  2. 3:3:23:1 H3PO4:HNO3:CH3COOH:H2O ~10min/100A
  3. 1:1:4 NH4OH:H2O2:CH3OH .36micron/min resist
  4. 1:1:1 HCl:HNO3:H2O
  5. 1-8:1HNO3:H2O
  6. 1 M HNO3 + light

Stainless Steel

  1. 1:1 HF:HNO3

Tantalum

  1. 1:1 HF:HNO3

Tin

  1. 1:1 HF:HCL
  2. 1:1 HF:HNO3
  3. 1:1 HF:H2O
  4. 2:7 HClO4:HAc

Titanium

  1. 50:1:1 H2O:HF:HNO3
  2. 20:1:1 H2O:HF:H2O2
  3. RCA-1 ~100 min/micron
  4. x%Br2:ethyl acetate - HOT
  5. x%I2:MeOH - HOT
  6. HF:CuSO4
  7. 1:2 NH4OH:H2O2
  8. 1:2:7, 1:5:4, 1:4:5(18 microns/min), 1:1:50 HF:HNO3:H2O
  9. COOHCOOH:H2O - any concentration
  10. 1:1:20 HF:H2O2:HNO3
  11. 1:9 HF:H2O - 12 A/MIN
  12. HF:HCL:H2O
  13. HCL - conc
  14. %KOH - conc
  15. %NaOH- conc
  16. 20% H2SO4 1 micron/min
  17. CCl3COOC2h3
  18. 25%HCOOH
  19. 20%H3PO4
  20. HF

Tungsten

  1. 1:1 HF:HNO3
  2. 1:1 HF:HNO3 - thin films
  3. 3:7 HF:HNO3
  4. 4:1 HF:HNO3 - rapid attack
  5. 1:2 NH4OH:H2O2 - thin films good for etching tungsten from stainless steel, glass, copper and ceramics. Will etch titanium as well.
  6. 305g:44.5g:1000ml K3Fe(CN)6:NaOH:H2O - rapid etch
  7. HCl - slow etch (dilute or concentrated)
  8. HNO3 - very slow etch (dilute or concentrated)
  9. H2SO4 - slow etch (dilute or concentrated)
  10. HF - slow etch (dilute or concentrated)
  11. H2O2
  12. 1:1, 30%:70%, or 4:1 HF:HNO3
  13. 1:2 NH4OH:H2O2
  14. 4:4:3 HF HNO3:HAc
  15. CBrF3 RIE etch
  16. 305g:44.5g:1000ml K3Fe(CN)6:NaOH:H2O - very rapid etch
  17. HCl solutions - slow attack
  18. HNO3 - slight attack
  19. Aqua Regia 3:1 HCL:HNO3 - slow attack when hot or warm
  20. H2SO4 dilute and concentrated - slow etch
  21. HF dilute and concentrated - slow etch
  22. Alkali with oxidizers (KNO3 and PbO2) - rapid etch
  23. H2O2

Vanadium

  1. 1:1 H2O:HNO3
  2. 1:1 HF:HNO3

Zinc

  1. 1:1 HCl:H2O
  2. 1:1 HNO3:H2O

Zinc Oxide

  1. 1:60 HCl:H2O - 1.9 microns/min
  2. 1:200 Hcl:H2O - 0.9 microns/min
  3. 1:500 HCl:H2O - 0.4 microns/min
  4. 1:900 HCl:H2O - 0.2 microns/min
  5. 1:100 HNO3:H2O - 0.9 microns/min
  6. 1:7 BOE - .06 microns/min
  7. 1:1:30 H3PO4:C6H8O7:H2O - 2.2 microns/min
  8. 1:5:60 H3PO4:C6H8O7:H2O - 1.8 microns/min
  9. 1:1:80 H3PO4:C6H8O7:H2O - 1.4 microns/min
  10. 1:1:150 H3PO4:C6H8O7:H2O - 1 micron/min
  11. 1:1:200 H3PO4:C6H8O7:H2O - 0.8 microns/min
  12. 1:2:300 H3PO4:C6H8O7:H2O - 0.65 microns/min

Zirconium

  1. 50:1:1 H2O:HF:HNO3
  2. 20:1:1 H2O:HF:H2O2