Macro Cell Based Process Design Kit Layout Dependent Effects
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Solution Overview
Problem
Traditional process design kits (PDKs) lack accurate modeling of layout-dependent effects and density gradients in advanced semiconductor processes, leading to variations in device performance and increased re-spin efforts during integrated circuit design.
Innovation Solution
An enhanced PDK that includes macro-cell libraries and dynamic electrical characteristics to simulate layout impacts, such as mismatch and parasitics, allowing for pre-simulation estimation of layout density and intelligent layout transformation to prevent design rule check violations, thereby reducing the gap between pre- and post-simulation results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional PDKs are used for circuit simulation, then the design process is simple, but layout-dependent effects and density gradients are not accurately modeled leading to device performance variations
Solution Approach 1:
The PDK is segmented into multiple hierarchical levels: device-level models for individual component behavior and macro-cell level models that capture layout-dependent effects. This segmentation allows accurate modeling of layout effects without requiring the entire PDK to be overly complex, as each segment handles specific aspects of the simulation.
Solution Approach 2:
Macro-cells are introduced as intermediary structures between traditional device models and full layout simulations. These macro-cells pre-compute and encapsulate layout-dependent effects, acting as mediators that provide accurate modeling without requiring direct integration of complex layout geometry into every simulation.
2Productivity
If layout impacts are guessed or estimated in simulation phase, then the design process is faster, but re-spin efforts increase during manufacturing
Solution Approach 1:
Layout-dependent effects and density gradients are pre-computed and embedded in macro-cell models before the actual circuit simulation. This preliminary action allows designers to use accurate models during simulation without performing complex layout analyses at that stage, maintaining speed while improving reliability.
Solution Approach 2:
The PDK incorporates feedback mechanisms where simulation results inform layout adjustments, and updated layout information refines the macro-cell models. This iterative feedback loop enables accurate prediction of layout impacts while allowing for corrections before manufacturing, reducing re-spin efforts.
3Quantity of substance
If feature size is continuously reduced to increase integration density, then more components fit on wafer, but physical and layout effects become more significant and harder to model
Solution Approach 1:
The PDK applies local quality by creating region-specific macro-cell models that account for local layout conditions and density variations. Different parts of the wafer can have different macro-cell models tailored to their specific layout characteristics, enabling accurate modeling of layout effects even as feature sizes shrink and density increases.
Data Source
AI summary
The present disclosure provides a system and method of designing an integrated circuit. A plurality of devices are selected and properties assigned to each of the plurality of devices. These plural devices having assigned properties are then combined into a macro cell whereby a density gradient pattern is generated for the macro cell. Layout dependent effect (LDE) parameters are determined for the macro cell as a function of the combination of plural devices, and electrical performance characteristics for the macro cell are simulated. A layout distribution of the plurality of devices within the macro cell can then be determined as a function of one or more of the simulated electrical performance characteristics, determined LDE parameters, and generated density gradient pattern. A design layout of an integrated circuit can be generated corresponding to the layout distribution for the macro cell.