Metal and Semiconductor Wet Etching
    1. Aluminum

      1. 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
    2. 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
    3. Aluminum Trioxide / Alumina / Sapphire

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

      1. 10:1 - H2O:HCl
    6. Brass

      1. FeCl3
      2. 20% NHSO5
    7. Bronze

      1. 1% CrO3
    8. Carbon

      1. H3PO4:CrO3:NaCN
      2. 50% KOH (or NaOH) – boiling
      3. HNO3 concentrated
      4. H2SO4 concentrated
      5. 3:1 - H2SO4:H2O2
    9. 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
    10. Cobalt

      1. 1:1 H2O:HNO3
      2. 3:1 HCl:H2O2
    11. 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
    12. 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
    13. 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
    14. 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
    15. 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
    16. Hafnium

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

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

      1. 1:1:20 - H2SO4:H2O2:H2O - 30 angstroms/sec
    19. Indium Gallium Phosphide

      1. conc HCl - fast
    20. Indium Phosphide

      1. 1:1 - HCl:H3PO4 - fast
    21. Indium Phosphide Oxide Etchants

      1. NH4OH
    22. Indium Tin Oxide (ITO)

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

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

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

      1. 1:1 - HAc:H2O2
    26. Magnesium

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

      1. 1:1 - HCl:H2O2
    28. 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
    29. Niobium

      1. 1:1 - HF:HNO3
    30. Palladium

      1. Aqua Regia 3:1 - HCl:HNO3 hot
    31. Photoresist (AZ type)

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

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

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

      1. 1:1 - HF:H2O
      2. 1:1 - HF:HNO3
      3. Sodium Carbonate boiling
      4. HF conc
    35. Rhenium, Rhodium and Ruthenium

      1. Aqua Regia 3:1 - HCl:HNO3 - Hot
    36. 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
    37. 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)
      5. Secco etch 2:1 HF:1.5M K2Cr2O7
      6. 5:1 NH4.HF:NaF/L (in grams)
      7. 1g:1ml:10ml:10ml NH4F.HF:HF:H2O:glycerin
      8. HF – hot
      9. 1:1 1:15, 1:100 HF:H2O
      10. BOE HF:NH4F:H2O
      11. 1:6 BOE:H2O
      12. 5:43, 1:6 HF:NH4F(40%)
      13. NaCO3 100 C 8.8 mm/h
      14. 5% NaOH 100 C 150 mm/h
      15. 5% HCl 95 C 0.5mm/day
      16. KOH see KOH etching of silicon dioxide and silicon nitride
    38. 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
    39. 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
    40. Stainless Steel

      1. 1:1 HF:HNO3
    41. Tantalum

      1. 1:1 HF:HNO3
    42. Tin

      1. 1:1 HF:HCL
      2. 1:1 HF:HNO3
      3. 1:1 HF:H2O
      4. 2:7 HClO4:HAc
    43. 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. CCl3COOC2H5
      18. 25%HCOOH
      19. 20%H3PO4
      20. HF
    44. 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
    45. Vanadium

      1. 1:1 H2O:HNO3
      2. 1:1 HF:HNO3
    46. Zinc

      1. 1:1 HCl:H2O
      2. 1:1 HNO3:H2O
    47. 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
    48. Zirconium

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