铜互连的终结？

Core Viewpoint - The copper interconnect era may be nearing its end as copper is no longer the optimal metallization choice for interconnects with critical dimensions below 10 nanometers, despite its unmatched performance for larger feature sizes [2][3]. Group 1: Challenges of Copper Interconnects - Copper faces significant challenges in miniaturization, particularly as its resistivity increases dramatically when the line width is below 10 nanometers, with resistance increasing approximately tenfold compared to bulk material [2]. - The requirement for diffusion barrier layers complicates the manufacturing of extremely small features, as the actual copper line thickness is reduced to 2 to 4 nanometers when accounting for the barrier layer thickness of at least 3 to 4 nanometers [2]. Group 2: Alternative Conductors - Ruthenium is emerging as a potential alternative conductor due to its lower resistivity and superior electromigration resistance compared to copper, especially for lines with critical dimensions of 17 nanometers or smaller [5]. - Ruthenium's compatibility with copper is crucial, as copper will likely remain the preferred metal for lines wider than 20 nanometers, making the interface between any alternative conductor and copper critical for device success [5]. Group 3: Research and Development - Samsung's research team, in collaboration with IMEC, has demonstrated that reducing the thickness of the barrier layer can lower overall line resistance, and that copper does not mix with ruthenium at the bottom of vias [6]. - The use of ruthenium allows for more flexible process integration, as it is easier to etch compared to copper, although it presents challenges in deposition and removal [5][9]. Group 4: Future Prospects - The semiconductor industry is beginning to explore the deposition conditions and properties of ruthenium, with findings suggesting that lower deposition pressures can yield denser, lower-resistance films, although adhesion may suffer [9]. - The introduction of ruthenium as a via or line material could represent a significant transformation in semiconductor manufacturing, although such changes are expected to take time as the industry lays the groundwork for this transition [10].