Wet Etching Recipes

   

Material to be Etched

Chemicals

Ratio

Comments

Aluminum (Al)

H3PO4 : Water : Acetic Acid : HNO3

16:2:1:1

PAN Etch;

200 nm/min @ 25 C;

600 nm/min @ 40 C

Aluminum (Al)

NaOH : Water

1:1

may be used at 25 C but etches faster at a higher temperature

Aluminum (Al)

H3PO4

---

must be heated to 120 C

Chromium (Cr)

HCl : Water

3:1

---

Chromium (Cr)

HCl:Glycerin

1:1

---

Copper (Cu)

HNO3 : Water

5:1

---

Copper (Cu)

Ammonium Persulphate

---

---

Gold (Au)

KI : I : Water

115 g : 65 g : 100 ml

---

Gold (Au)

HCl :  HNO3

3:1

Aqua Regia;

discard after use

Iron (Fe)

HCl : Water

1:1

---

Iron (Fe)

HNO3 : Water

1:1

---

Lead (Pb)

Acetic Acid : H2O2

1:1

for dissolving solder connections

Lead (Pb)

Acetic Acid : H2O2 : Water

2:2:5

---

Molybdenum (Mo)

HCl : H2O2

1:1

---

Molybdenum (Mo)

H2SO4 : HNO3 : Water

1:1:1

---

Nichrome

H2SO4

---

use at 100 C

Nichrome

HCl :  HNO3 : Water

1:1:3

---

Nickel (Ni)

HCl :  HNO3

5:1

 ---

Nickel (Ni)

HF:  HNO3

1:1

 ---

Palladium (Pd)

HCl :  HNO3

3:1

Aqua Regia;

discard after use

Platinum (Pt)

HCl :  HNO3 : Water

3:1:4

use at 95 C

Platinum (Pt)

HCl :  HNO3

8:1

age for 1 hour;

use at 70 C

Polysilicon (Si)

HNO3 : Water : HF

50:20:1

remove oxide first;

540 nm/min @ 25C

Polysilicon (Si)

HNO3 : HF

3:1

remove oxide first;

high etch rate:

4.2 micron/min

         

Material to be Etched

Chemicals

Ratio

Comments

Silicon (Si)

HF : HNO3 : Water

2:2:1

---

Silicon (Si)

HNO3: HF : Acetic Acid

5:3:3

---

Silicon (Si)

NaOH in Water

---

for dissolving the die from the package to allow inspection of eutectic die attach;

16 hours @ a temperature near boiling point

Silicon dioxide (SiO2)-

thermally grown

NH4F:HF

6:1

Buffered HF;

120 nm/min @ 25 C

Silicon dioxide (SiO2)-

thermally grown

HF : Water

1:10

slower etch;

30 nm/min @ 25 C

Silicon dioxide (SiO2)-

thermally grown

HF : Water

1:100

very slow etch;

1.8 nm/min @ 25 C

Silicon dioxide (SiO2)-

thermally grown

HF

---

very rapid etch;

1.8 microns/min @ 25 C

Silicon dioxide (SiO2)-

CVD

HF : Water

1:10

---

Silicon dioxide (SiO2)-

Phosphorus-doped

HF : Water

1:10

---

Silicon nitride (Si3N4)

refluxing phosphoric acid

---

use at 180C;

6.5 nm/min @ 25 C;

will also etch Al rapidly; plasma etching is preferred for removing Si3N4

Silver (Ag)

NH4OH : H2O2

1:1

rapid etch

Silver (Ag)

HNO3 : Water

1:1

---

Tantalum (Ta)

HF : HNO3 : Water

2:2:5

---

Tin (Sn)

HF : HNO3

1:1

---

Tin (Sn)

H2SO4

---

use at 80 C

Titanium (Ti)

HF : H2SO4 : Water

1:30:69

use at 70 C

Titanium-Tungsten (TiW)

H2O2

---

very selective;

5 nm/min @ 25 C

Tungsten (W)

HF : HNO3

1:1

---

Vanadium (Va)

HF : HNO3 : Water

1:1:1

---

Reference: Failure and Yield Analysis Handbook, Technology Associates

 

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