sicoh

**SiCOH** (Carbon-doped Oxide, CDO) is the **industry-standard low-k dielectric material** — a modified form of SiO₂ where some Si-O bonds are replaced with Si-CH₃ groups, reducing the film density and polarizability to lower the dielectric constant to $kappa approx 2.5-3.0$. **What Is SiCOH?** - **Composition**: Silicon, Carbon, Oxygen, Hydrogen in an amorphous network. - **Deposition**: PECVD using organosilicon precursors (DEMS, OMCTS). - **$kappa$ Tuning**: More carbon (methyl groups) = lower $kappa$ but weaker mechanical properties. - **Porous SiCOH**: Adding porosity pushes $kappa$ below 2.5 (ULK region). **Why It Matters** - **Workhorse**: Used in every advanced logic process from 90nm to 3nm. - **Compatibility**: Integrates well with existing BEOL processes (etch, CMP, barrier deposition). - **Trade-off**: Lower $kappa$ variants are increasingly fragile, requiring careful process optimization. **SiCOH** is **the backbone of modern BEOL** — the engineered glass that insulates billions of copper wires running through every advanced processor.