Abstract:
With the ongoing miniaturization of device sizes inintegrated circuit component, traditional copper (Cu) interconnects encounter performance limitations below the 5 nm technology node due to the size-induced increase in resistivity. This challenge highlights the need for novel interconnect materials and fabrication techniques. This study utilized ALD with a Ru(EtCp)
2/O
2 system on SiO
2 substrates to examine the influence of optimizing critical process parameters on ruthenium (Ru) film growth and conductive network formation. These parameter include ALD cycles, precursor/oxygen pulse durations, and deposition temperature. The objective was to provide experimental insights for refining the ALD process to produce high-conductivity Ru interconnect films. Results indicated that Ru films deposited with fewer than 200 ALD cycles exhibited discrete island-like structures. A continuous conductive network formed when the cycle count reached 500. The metallic Ru film purity exceeded 90%. On SiO
2 substrates, the deposited Ru film thickness was 19.7 nm, with a corresponding resistivity of 25.6 μΩ·cm. Optimizing the precursor and oxygen pulse durations to 5 s and 10 s, respectively, increased the deposition rate to 0.510 Å/cycle. Temperature regulation, which influenced grain boundary diffusion, revealed that at 325 ℃, the conductive network remained stable, yielding a sheet resistance of 18 Ω. In contrast, at 350 ℃, thermal stress induced grain coarsening and network fragmentation, increasing the sheet resistance to 59 Ω.