Ruthenium Precursors for the Semiconductor Industry

The advancements in digitalization, artificial intelligence, autonomous driving and high performing end-devices have given rise to smaller and yet more powerful logic chips. Therefore, the scaling of high-end technology nodes is moving forward - leading to smaller transistors and interconnects. While research continues to develop smaller transistors, difficulties occur when creating finer & thinner interconnects made from copper.

There are 3 main pitfalls with downsizing copper interconnects:

• Copper wires need to be encased with barrier layers to avoid a corruption of the neighboring materials. Barrier layers are thus an obstacle in reducing copper wires’ sizes.
• The thinner a copper wire becomes, the more likely electromigration occurs.
• With the shrinking dimensions of the interconnects, the resistivity of copper increases.

Due to the above-mentioned disadvantages, new materials for interconnects needs to be considered. One of the most promising candidates replacing copper is ruthenium as the researchers Wan et. al. have shown in their IITC conference paper Subtractive Etch of Ruthenium for Sub-5nm Interconnect.

Metallic ruthenium films - made from volatile precursors by evaporation - show superior material properties when being applied in wire diameters of few nanometers or less.

The advantages of using ruthenium include:

• Resistance to thermal and electrical degradation - improving longevity of the transistors
• High melting point - allowing for heat prone applications
• Potential to create barrierless interconnects – allowing for smaller device architectures and reducing the number of process steps
• Low resistivity – facilitating higher performing chips with faster switching time

You can choose out of 8 ruthenium compounds which can be applied via atomic layer deposition or chemical vapor deposition as new interconnect material. In addition, our ruthenium precursors can be used for hard masking.

Applying precious metal-based compounds in the metallization of the chip is new to the semiconductor industry. Heraeus can support you with its in-depth experience in precious metal chemistry and extensive experience in precious metal services.