SRAM Boost Capacitor Short Circuit Detection
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Solution Overview
Problem
In SRAMs, the increasing narrow spacing between metal lines in boost capacitors due to process variations can lead to short circuits, resulting in IC yield loss and potential failure.
Innovation Solution
A circuit and method are implemented to detect short circuits in the boost capacitor of an SRAM's assist circuit using a sense circuit and sample circuit, which monitor state changes indicative of a short circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If metal lines spacing is reduced to improve floor planning efficiency, then IC area utilization improves, but short circuit risk increases
Solution Approach 1:
The patent implements a detection circuit that performs preliminary detection of short circuits in the boost capacitor before they cause IC failure. The sense circuit continuously monitors the voltage on the second plate, and the sample circuit periodically samples this voltage to detect short circuit conditions early, enabling preventive action before reliability is compromised.
Solution Approach 2:
The patent introduces an intermediary detection system consisting of the sense circuit and sample circuit that mediates between the narrow-spaced metal lines and the potential short circuit failure. This intermediary monitoring mechanism allows the system to operate with narrow spacing while maintaining reliability through continuous surveillance and early detection of abnormal conditions.
2Productivity
If metal lines spacing is reduced due to process variations, then manufacturing density improves, but manufacturing precision requirements increase
Solution Approach 1:
The detection circuit provides self-service monitoring of the boost capacitor's health status. The sense circuit automatically detects voltage changes on the second plate that indicate short circuit conditions, and the sample circuit periodically samples this information without requiring external intervention. This self-monitoring system compensates for the increased precision risks associated with narrow metal line spacing.
Solution Approach 2:
The patent implements a feedback mechanism where the sense circuit continuously monitors the voltage on the second plate and provides this information to the sample circuit. When a short circuit is detected through voltage state changes, the system can trigger appropriate responses. This feedback loop enables the manufacturing system to maintain high density while managing precision risks through continuous monitoring and adaptive control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively detects short circuits in the boost capacitor, enabling timely mitigation to prevent IC failure and improve yield, thereby ensuring reliable SRAM operation.
Implementation Method 1
a boost capacitor coupled to boost a voltage on the conductive line. The boost capacitor includes first and second plates
Implementation Method 2
a sense circuit having an input coupled to one of the first and second plates of the boost capacitor and an output
Implementation Method 3
a sample circuit coupled to the output of the sense circuit. The sample circuit is configured to detect a short circuit in the boost capacitor based on a state change at the output of the sense circuit
Data Source
AI summary
An integrated circuit includes a semiconductor substrate and integrated circuitry on the semiconductor substrate. The integrated circuitry includes a static random access memory (SRAM) array including a conductive line and an assist circuit having a boost capacitor coupled to boost a voltage on the conductive line. The boost capacitor includes first and second plates. The integrated circuit further includes a sense circuit having an input coupled to one of the first and second plates of the boost capacitor and an output and a sample circuit coupled to the output of the sense circuit. The sample circuit is configured to detect a short circuit in the boost capacitor based on a state change at the output of the sense circuit.