Table 1 Comparison of Co alloy elements for self-forming diffusion barrier (SFB): six design rules were used to determine which of the five dopants is suitable as a self-forming barrier material. The activity coefficient and solubility of the dopant are thermodynamically calculated values. The resistivity of each metal represents the bulk value of the resistivity.
From: Robust Co alloy design for Co interconnects using a self-forming barrier layer
Design rule of Co self-forming barrier | Cr | Zn | Mn | Fe | Sn |
|---|---|---|---|---|---|
Oxide enthalpy of formation | Moderate | Moderate | Moderate | Moderate | Moderate |
Reaction phase with Co/SiO2 at 450 °C | Cr2O3 | Zn2SiO4 | MnSiO3, CoSiO3 | Fe–Co–Si compound | SnO2 |
Intermetallic compound (IMC) formation at 450 °C | Not formed | Not formed | Not formed | Not formed | Formed |
Solubility at 450 °C (at%) | 0.31 | 4.88 | 8.11 | 10.11 | 2.12 |
Activity coefficient of dopant | 68.572 | 0.997 | 0.463 | 0.263 | 2.653 |
Resistivity (μΩ∙cm) | 12.50 | 5.90 | 144 | 9.61 | 22.8 |
