Acetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2 O3 ; Ga; GaAs; GaN; In; Fe; Pb; Ni; NiO, Ni2 O3 ; Sn; SnO2 ; Ti; Zn Hydrofluoric Acid (HF): GaAs; Ni; SiO2 ; Ti Nitric Acid (HNO 3 ): C; Cu; GaAs; In; Fe; Pb; Ni; Ag; Pd; Pt; Sn; Ti; Zn; ZnO Phosphoric Acid (H3 PO4 ): Al; Cu; GaAs; GaN; Fe; Ni; SiN; ZnO Potassium Hydroxide (KOH): Al; C; Cu; Ag; GaAs; Si; Ti Sodium Hydroxide (NaOH): Al; Cu; Ag; Ti; GaAs; GaN Sulfuric Acid (H 2SO4 ): C; Cu; GaAs; Fe; Pb; Ni; Ti Aqua Regia (3 HCl : 1 HNO 3 ) etches all metals Etchant ? Rate Also etches— Aluminum (Al) 19 H3 PO4 : 1 HAc : 1 HNO3 : 2 H2 O 40 Å/s SiN, M 10% K3 Fe(CN) 6 100 Å/s Aluminum Oxide (Al2O3) 1 NH4 OH : 1 H2 O2 : 3 H2 O @ 80 ºC Al, Poly Brass (alloy Cu : Zn) FeCl3 Cu, Ni 20% NH4 SO5 Al Bronze (alloy Cu : Sn) 1% CrO3 Carbon (C) H3 PO4 : CrO3 : NaCN SiN Chromium (Cr) 2 KMnO4 : 3 NaOH : 12 H2 O Al Copper (Cu) 30% FeCl3 Ni 20% KCN Ag, Au Gallium Arsenide (GaAs) 5% Br2 in CH3 OH Fe 1 NH4 OH : 1 H2 O2 Al, Ag, Poly Gold (Au) 1 I2 : 2 KI : 10 H2 O Fe KCN Ag, Cu Iron (Fe) 1 I2 : 2 KI : 10 H2 O Au Nickel (Ni) 30% FeCl3 Cu Polymers (e.g.: photoresist, wax, epoxies) 5 NH4 OH : 1 H2 O2 @ 120 ºC Al Silicon (Si) 64 HNO3 : 3 NH4 F : 33 H2 O 100 Å/s M 61 EDA : 11 C6 H4 (OH) 2 : 28 H2 O 78 Å/s Poly Silicon Oxide (SiO 2) 1 HF : 5 NH4 HF : 5 H2 O (BOE) 20 Å/s M, SiO2 Silver (Ag) 1 NH4 OH : 1 H2 O2 Al, Poly Stainless Steel (alloy Fe : C : Cr) 1 HF : 1 HNO3 M Tin (Sn) 2 HClO4 : 7 HAc Doesn’t etch— SiO2 , Si, PR ZnO, SiO2 , SiN, Si, M, PR SiO2 , SiN, Si, M SiO2 , SiN, Si, M, PR SiO2 , SiN, Si, M, PR SiO2 , SiN, Si, PR SiO2 , Si, PR SiO2 , SiN, Si, M, PR SiO2 , SiN, Si, M, PR Al2 O3 , SiO2, SiN, Si, M, PR SiO2 , SiN, Si, M SiO2 , SiN, Si, M SiO2 , SiN, Si, M, PR Al2 O3 , SiO2, SiN, Si, M, PR SiO2 , SiN, Si, M, PR SiO2 , SiN, Si, M, PR SiO2 , SiN, Si, M SiN, PR SiO2 , SiN, M SiN, Si SiO2 , SiN, Si, M SiN, PR SiO2 , SiN, Si, PR H2 O HCl HF HNO3 H2 SO4 H3 PO4 HAc HClO4 H2 O2 NH4 OH NH4 F CH3 OH EDA C6 H4 (OH) 2 NaOH KOH KCN NaCN KFe(CN) 6 KMnO4 FeCl3 NH4 SO5 KI I2 Br2 CrO3 : : : : : : : : : : : : : : : : : : : : : : : : : : deionized (DI) water (l) hydrochloric acid (38%, aq) hydrofluoric acid (49%, aq) nitric acid (70%, aq) sulfuric acid (96%, aq) phosphoric acid (85%, aq) acetic acid (l, H3 COOH) perchloric acid (68%, aq) hydrogen peroxide (30%, aq) ammonium hydroxide (30%, aq) ammonium fluoride (40%, aq) methanol (l) ethylenediamine (l, NH2 O(CH2 ) 2 NH2 ) pyrocatechol (s) sodium hydroxide (s) potassium hydroxide (s) potassium cyanide (s) sodium cyanide (s) potassium ferrocyanide (s) potassium permanganate (s) ferric chloride (s) ammonium persulfate (s) potassium iodide (s) iodine (s) bromine (l) chromic oxide (s) SiO2 SiN Si M PR Poly : : : : : : silicon oxide silicon nitride (Si3 N4 , Si9 N12) mono- or polycrystalline silicon metals photoresist (cured) other polymers