How to Clean Silicon Wafers

Silicon WafersSilicon wafers form the foundation of electronics manufacturing. Almost every electronic device that you use today uses them. As such, it is helpful to learn about silicon wafer polishing and the cleaning process.


Silicon wafers are very sensitive pieces–they can be contaminated simply by being exposed to air. As such, cleaning the wafers is an indispensable step in the manufacturing process. Thanks to standardization, there is an industry-recognized, three-step process for cleaning. We will summarize it here.


The Cleaning Process

The first step is solvent cleaning. The wafers are dipped in acetone to eliminate oils and contaminants. Then, the wafers move to a container with methanol. The first step involves two liquids because the solvent (acetone) can leave a residue that might contaminate the wafer. Methanol removes leftover residue.


After getting rinsed with DI water and blow-dried with nitrogen, the wafer undergoes RCA-1 cleaning. This step oxidizes the wafer. The RCA-1 solution is a mixture of ammonium hydroxide and DI water.


Finally, the wafers are placed in a hydrofluoric acid dip. The acid dip removes the oxidized layer formed form the second step. Hydrofluoric acid is highly volatile, so the step requires protective equipment.


This standardized cleaning procedure purges the wafer of contaminants, ensuring they are ready to proceed with the manufacturing process. Many wafer manufacturing firms offer this service as part of their silicon wafer polishing solutions.