Wet etching and cleaning area The equipment in the wet etching and cleaning area is divided into spin and bath equipment: Silicon oxide etching equipment This equipment is intended for etching silicon oxide with hydrofluoric acid (HF) solution buffered by ammonium fluoride (NH4F), known as BOE (Buffered Oxide Etch). The chemical solution is loaded manually. It is made of natural polypropylene, the piping of Polyvinylidene fluoride (PVDF), which has good acid resistance. Silicon nitride etching equipment This equipment is intended for etching silicon nitride (Si3N4), with 80% phosphoric acid solution (H3PO4) at 160-165°C. The chemical solution is loaded manually. The general design of this equipment is almost similar to that for silicon oxide etching. It is made of natural polypropylene, the piping of Polyvinylidene fluoride (PVDF), which has good acid resistance. SPRAY SOLVENT TOOL (SST) It is manual loading equipment designed for the use of flammable solvents for the removal of photosensitive resins, etching of polymers, polyamides and organic contaminants. It is made of stainless steel, a material resistant to the attack of organic solvents. SPRAY ACID TOOL (SAT) It is designed for cleaning, stripping & etching processes: Piranha (H2SO4: H2O2) SC1 (NH4OH : H2O2 : H2O) SC2 (HCl : H2O2 : H2O) DHF (HF : H2O). Spin Rinser Dryer (SRD) This equipment is dedicated to the final rinsing and drying of wafers after any process has been carried out. Rinsing the wafers with ultra pure water and drying with hot nitrogen which evaporates the water and moisture from the surface. The chemicals used The chemicals used are: HF at 21°C with and without direct contact NH4F at 21 °C in direct contact H3PO4 at 160 °C in direct contact H2SO4 at 90°C no direct contact NH4OH at 60°C no direct contact HCl at 60°C no direct contact H2O2 at 60°C, and 90°C no direct contact EKC commercial solution at 70°C no direct contact IPA Personal protective equipment In the case of baths such as etching oxide and silicon nitride, PPE is mandatory, given the direct contact with the chemical solution, and is the apron, glasses, mask and chemical-resistant gloves.