Alignment Key DRC for Abutting Cell Placement Accuracy
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Solution Overview
Problem
In semiconductor design, the placement of pre-defined cells in integrated circuits (ICs) often results in errors due to the increasing complexity of advanced node technologies and the incorporation of third-party intellectual property (IP), making it difficult to ensure correct alignment and orientation, which can impact manufacturability and functionality.
Innovation Solution
The method involves creating alignment key shapes for each cell, stored in a software alignment layer, which are graphically superimposed to determine correct placement. These key shapes are checked using design rule checks (DRC) to identify and correct disallowed placements, ensuring that the cells form pre-defined shapes indicating correct orientation and interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cells are placed in physical layout design using traditional methods, then design flexibility is maintained, but placement errors occur due to increasing complexity and third-party IP incorporation
Solution Approach 1:
The patent applies preliminary action by pre-defining correct alignment key shapes and placement rules before the actual cell placement process. The alignment key shapes are created and stored in a database with their correct geometric configurations established in advance, allowing the DRC tool to automatically verify placements against these pre-established standards, thereby preventing errors before they occur despite increasing design complexity
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of alignment key shapes that serve as mediators between the cell placement process and the verification process. These alignment keys are graphical representations that mediate the complex verification task by providing a simplified visual and computational method for checking placement correctness, enabling automatic validation without requiring manual inspection of complex third-party IP cells
2Measurement precision
If alignment verification is performed manually, then placement correctness can be checked, but time consumption increases and errors may be missed
Solution Approach 1:
The patent implements self-service by enabling the DRC tool to automatically perform alignment verification without requiring manual intervention. The system serves itself by using the pre-defined alignment key shapes and placement rules to automatically check and validate cell placements, providing both high verification accuracy and rapid processing. The tool independently identifies mismatches between actual placements and correct alignment keys, eliminating the need for time-consuming manual verification while maintaining precision
Solution Approach 2:
The patent replaces the mechanical manual verification process with an automated computational system. Instead of relying on manual visual inspection and physical measurement methods, the system uses computer-based DRC tools to automatically compare placement geometries against pre-defined alignment key shapes, substituting human manual operations with automated mechanical/computational verification that is both faster and more accurate
3Productivity
If third-party IP cells are incorporated to reduce design time, then productivity increases, but placement errors increase due to unfamiliarity with cell geometry
Solution Approach 1:
The patent applies universality by creating a universal alignment key verification system that works with all cell types, including third-party IP cells. The DRC tool uses the same alignment key shapes and verification rules regardless of the cell source, making the system universally applicable to both proprietary and third-party cells. This universal approach allows rapid incorporation of third-party IP while maintaining placement correctness through automated verification that does not require designer familiarity with specific cell geometries
Solution Approach 2:
The patent implements feedback by providing immediate automated verification results when third-party IP cells are placed. The DRC tool continuously checks placements against the pre-defined alignment key shapes and provides real-time feedback on correctness, allowing designers to quickly identify and correct placement errors. This feedback mechanism enables the rapid use of third-party IP cells while maintaining high placement accuracy through continuous automated validation
Data Source
AI summary
Methods and a computer program product are described for placing, by an electronic design tool, a first alignment key shape of a first cell and a second alignment key shape of a second cell positioned on a common edge where the first cell abuts the second cell in a physical layout design. An abutting alignment key shape is formed by placement of the first alignment key shape and the second alignment key shape in the physical layout design. The abutting alignment key shape is checked by a design rule to identify a disallowed cell placement of the first cell relative to the second cell when the abutting alignment key shape does not form a pre-defined shape of a correct size. The disallowed cell placement is corrected, by a designer, through substitution of an allowed cell placement to provide a corrected physical layout design for manufacture of the IC.