Introduction to GDSII and OASIS

Semiconductor design relies heavily on accurate physical layout data. The two most critical formats are GDSII and OASIS. GDSII (Graphic Design System II) has been the industry standard for decades, storing design information like shapes and layers. However, the increasing complexity of modern packaging, specifically 2.5D and 3D ICs, requires advanced interconnectivity and metadata capabilities that GDSII cannot provide. OASIS (Open-Architecture Standard for Inter-Chip Interconnect) has emerged as the best-in-class solution. It provides a much richer, extended payload capacity for attaching behavioral models, design flow metadata, and connectivity information alongside the raw geometric data. Understanding this crucial difference—GDSII focuses on geometry; OASIS focuses on system-level interoperability—is key to modern EDA flows.

Key Aspects of OASIS Implementation

Implementing OASIS requires a deep understanding of the full chip stack and the surrounding interfaces. The process isn't just about converting formats; it's about structuring the data model itself. Our process involves ingesting raw GDSII layers, mapping them to the correct OASIS blocks, and then enriching them with behavioral information derived from SPICE simulations and formal verification reports. For instance, we can attach timing constraints directly to a net segment in the OASIS file, something GDSII cannot do efficiently. This ability to co-locate physical and electrical information is critical for advanced verification and automated sign-off. Our tooling handles this schema mapping seamlessly across various node technologies, accelerating design closure by preventing format-driven back-and-forth review cycles.

Best Practices for Flow Integration

To maximize the benefits of OASIS, your design flow must be structured around data handoff, not file handoff. Ensure that the output of your physical verification tools (like Calibre and Assura) is tagged with machine-readable metadata that can be consumed by the OASIS toolchain. Specifically, when migrating from GDSII, validate that all critical nets (the ones carrying signal integrity information) are identified and tagged with their source process corner, via the OASIS structure. We recommend integrating automated checks immediately after layout generation to ensure metadata completeness, which dramatically reduces the risk of missing design intent and subsequent tape-out delays. This advanced level of integration transforms layout data into actionable, verifiable design records.

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