Recipe for 6:1 Buffered Oxide Etch (BOE) with Surfactant

 

 

Chemicals Required:

·      100 g Ammonium Fluoride (NH4F)

·      150 ml DI Water

·      25 ml 49% Hydrofluoric Acid (HF)

·      100 ml 0.1% Triton

 

Safety Preparation:

Be sure to wear protective lab gear (acid gloves, lab coat, eye protection, etc.) when preparing BOE because of its high HF content.

 

Procedure:

Begin by weighing out 100 g of NH4F into a glass beaker. Add 150 ml of DI water and apply heat while stirring to speed up the dissolution of NH4F. Once completely dissolved and solution has cooled to a lukewarm temperature, transfer it into a Teflon beaker (or a beaker of another material impervious to HF) and move the beaker into a chemical hood. Add 25 ml of 49% HF into the solution and stir until mixed thoroughly. Lastly, add 100 ml of 0.1% Triton to the solution and stir BOE until it appears transparent. Store BOE in a Teflon or polymer bottle for long-term storage.