Antenna Cell Layer Hopping for IC Net Antenna Violations
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Solution Overview
Problem
As technology nodes decrease, integrated circuits face challenges in routing nets due to reduced channel sizes, leading to antenna violations which conventional layer hopping and antenna diodes fail to address predictably, causing design rule checking convergence issues and signal delay variations.
Innovation Solution
Implementing an antenna cell as a predefined interconnect structure that remedies antenna violations by layer hopping to the top layer, reducing signal delay variations and improving design rule checking convergence without the need for antenna diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional layer hopping is used to remedy antenna violation, then antenna violation is addressed, but design rule checking convergence challenges occur and signal delay variations increase
Solution Approach 1:
The antenna cell is pre-configured with a specific layer hopping pattern (from lower layer to top layer) before routing completion. This preliminary configuration ensures predictable antenna violation remediation without causing design rule checking convergence issues, as the layer hopping behavior is predetermined rather than dynamically determined during DRC.
Solution Approach 2:
The invention changes the layer parameter of the antenna cell from a dynamic, context-dependent value to a fixed parameter (top layer). This parameter change makes the antenna cell's behavior predictable and consistent, eliminating signal delay variations and design rule checking convergence challenges that arise from unpredictable layer hopping.
2Reliability
If antenna diodes are positioned within channels to avoid antenna violation, then antenna violation is prevented, but channel size and die size increase
Solution Approach 1:
Instead of adding antenna diodes within the channel (horizontal dimension), the invention uses vertical layer hopping to the top layer to remedy antenna violations. This dimensional shift from horizontal channel space to vertical layer space eliminates the need for additional channel width while maintaining effective antenna violation prevention.
Solution Approach 2:
The invention extracts the antenna violation remediation function from the channel structure and relocates it to the top layer through the antenna cell. This separation removes the need for antenna diodes within channels, preserving channel size and reducing overall die area.
3Area of stationary object
If routing nets over macro circuits is performed to reduce channel size, then channel size and die size are reduced, but antenna violations occur that require remediation
Solution Approach 1:
The antenna cell serves as an intermediary structure between the routed net and the top layer. It provides a controlled mechanism for layer hopping that remedies antenna violations without requiring changes to the net routing path over macro circuits, thus maintaining reduced channel size while preventing antenna violations.
Solution Approach 2:
The invention segments the net into two parts: the routed segment over the macro circuit (maintaining reduced channel size) and the antenna cell segment (providing layer hopping to remedy antenna violation). This segmentation allows the net to benefit from compact routing while simultaneously addressing antenna violation through structured layer transitions.
Data Source
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Figure 3A~3B
AI summary
A method and system for fixing antenna violation of antenna in an integrated circuit. A pin of a macro circuit is selected, the pin being electrically coupled to a gate of a transistor. A gate area and an antenna ratio for a layer of the integrated circuit is determined and a net area of a net which avoids antenna violation in the integrated circuit is calculated. A length of the net with the net area based on the gate area and the antenna ratio is identified. The antenna cell is positioned across a remainder of a segment of the net in a layer resulting from a portion of the segment being removed, where a distance from the portion to the gate over the net is the length and where the antenna cell routes the net to a top layer of the integrated circuit independent of a position of the antenna cell in the integrated circuit.