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Overview
IBM is pioneering semiconductor innovation by exploring alternative interconnect metals to overcome the limitations of traditional copper at advanced technology nodes. To accelerate material discovery and evaluation, IBM collaborated with Synopsys and leveraged the QuantumATK simulation platform. This partnership enabled IBM to efficiently screen and analyze new metal candidates, supporting the development of next-generation interconnects for higher performance and reliability.
Challenges
- Material Screening: Efficiently narrowing down a wide range of metal candidates to those with the right combination of conductivity and reliability.
- Process Compatibility: Integrating new materials without disrupting established manufacturing processes or device architectures.
- Experimental Correlation: Aligning simulation results with physical measurements to ensure predictive accuracy and practical viability.
Solution
IBM Research and Synopsys collaborated to deploy a comprehensive, simulation-based workflow for evaluating new interconnect metals. Key elements included:
- Atomic-scale Simulation: Utilized QuantumATK to model new-generation metals (Ru, Co, W) at the atomic level, accounting for grain boundary and surface scattering effects.
- Systematic Screening: Developed a methodology to go beyond bulk resistivity comparison, incorporating the impact of adhesion liners, wetting, and diffusion barrier layers on overall conductor performance.
- Automated Grain Boundary Analysis: Leveraged Sentaurus Materials Workbench (SMW) to automate the construction and relaxation of a large set of grain boundaries, enabling accurate extraction of reflection coefficients and grain boundary resistivity.
- Comprehensive Metal and Via Characterization: Assessed line and via resistance as a function of conductor width and liner thickness, identifying the impact of different encapsulation materials.
- Integrated Simulation Workflow: Passed simulation parameters from QuantumATK and SMW to Raphael FX, which, in combination with Process Explorer, enabled early RC parasitic assessment of new metals in complex 3D interconnect structures.
- Design Technology Co-Optimization (DTCO): Enabled technology development teams to efficiently identify and validate promising interconnect candidates for experimental integration into advanced logic and memory processes.
Figure 1. Complete and systematic workflow in QuantumATK for characterizing and screening new interconnect metals.
Results
The joint study revealed that the face-centered cubic (fcc) phase of ruthenium could be a superior alternative to copper for interconnects below 21nm line width. QuantumATK simulations showed that fcc Ru lines, when combined with optimized thin adhesion liners, deliver lower line and via resistance compared to copper, enabling improved performance at advanced nodes.
Key findings include:
- Superior Conductor Performance: Fcc Ru demonstrated lower line and via resistance than copper in tight-pitched interconnects, primarily due to reduced conductor volume lost to surrounding layers.
- Comprehensive Metal Screening: The QuantumATK-to-Raphael FX workflow provided a systematic, automated process for screening new interconnect metals, accounting for bulk properties, grain boundary scattering, and interface effects.
Actionable Technology Insights: The simulation results enabled IBM and Synopsys teams to efficiently identify promising metal candidates for experimental validation and integration into future logic and memory processes.
Impact
Through this collaboration, IBM and Synopsys have pioneered a robust, computationally-driven approach to interconnect innovation. The ability to accurately model and screen alternative metals at the atomic scale accelerates the development of next-generation semiconductor technologies, helping the industry overcome scaling challenges and achieve higher performance in advanced logic devices.
