nickel silicide (nisi)

**Nickel Silicide (NiSi)** is the **current industry-standard contact silicide** — offering the lowest resistivity, lowest silicon consumption, and lowest formation temperature among common silicides, making it ideal for advanced nodes with ultra-shallow junctions. **What Is NiSi?** - **Resistivity**: ~15-20 $muOmega$·cm (comparable to CoSi₂). - **Si Consumption**: Only 1.8 nm of Si per nm of Ni (vs. 3.6 for CoSi₂). Critical for shallow S/D junctions. - **Formation Temperature**: ~350-450°C (first anneal). Much lower thermal budget than CoSi₂ or TiSi₂. - **Challenge**: NiSi is metastable. At T > 700°C, it transforms to NiSi₂ (high resistivity). Thermal budget must be carefully managed. **Why It Matters** - **Shallow Junctions**: Low Si consumption preserves ultra-shallow S/D regions at 45nm and below. - **Low Thermal Budget**: Compatible with high-k/metal gate, strained silicon, and other thermally sensitive features. - **Agglomeration**: Prone to morphological instability at high temperatures — a key reliability concern. **NiSi** is **the modern workhorse of contact metallurgy** — delivering the lowest contact resistance with minimal disturbance to the delicate structures underneath.