IMS- Micro/Nano Fabrication Facility
Metal and Semiconductor Wet Etching

Aluminum

Aluminum Gallium Arsenide

Aluminum Trioxide / Alumina / Sapphire

Antimony

Bismuth

Brass

Bronze

Carbon

Chromium

Cobalt

Copper

Epoxies

Gallium Arsenide

Germanium

Gold

Hafnium

Indium

Indium Gallium Arsenide

Indium Gallium Phosphide

Indium Phosphide

Indium Phosphide Oxide Etchants

Indium Tin Oxide (ITO)

Iridium

Iron

Lead

Magnesium

Molybendum

Nickel

Niobium

Palladium

Photoresist (AZ type)

Platinum

Polymer (I)

Polymer (II)

Rhenium, Rhodium and Ruthenium

Silicon

Silicon Dioxide / Quartz / Glass

Silicon Nitride

Silver

Stainless Steel

Tantalum

Tin

Titanium

Tungsten

Vanadium

Zinc

Zinc Oxide

Zirconium

  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
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