sulfur dioxide (SO₂)

Sulfur dioxide (SO₂) is a specialized gas in semiconductor manufacturing, primarily utilized for its unique reactive properties in etching, surface treatment, and material modification. While not as ubiquitous as silane or ammonia, it plays a critical role in high-precision fabrication.

1. Plasma Etching and Selectivity Enhancement

Trenches are formed in silicon using an anisotropic chemical or reactive ion etch process upon a masked silicon substrate. Chemistries for etching silicon typically utilize combinations of such chemicals as hydrogen bromide (HBr), chlorine (Cl₂), oxygen (O₂), nitrogen fluoride (NF₃), sulfur hexafluoride (SF₆), and nitrogen (N₂).

2.  Photoresist Stripping and Ashing

3. Surface Cleaning and Passivation

It can be used in specialized gas-phase cleaning to remove metallic contaminants or to passivate sensitive surfaces. The copper surfaces to prevent oxidation and improve the adhesion of subsequent dielectric layers.