Etching is the process of using chemical and physical methods to selectively remove unwanted materials from the surface of a silicon wafer.

Boron trifluoride is an important catalyst widely used in organic synthesis and petrochemical industry. It is used in many organic chemical reactions such as alkylation, polymerization, isomerization, addition, synthesis and decomposition.

standard gas is a mixture of gases with an accurate known concentration

Helium is a colorless, odorless, and very stable gas that occurs in nature in very small amounts. Although it is not one of our most common elements, helium has a wide range of applications in science, industry and medicine.