Fuse Circuit Potential Control for Semiconductor Memory Reliability
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Solution Overview
Problem
Semiconductor memory devices face reliability and productivity issues due to reconnection of cut fuses, which can occur through electrical and chemical migration, leading to defective products and increased costs from abandoning devices with single memory cell failures.
Innovation Solution
A fuse circuit with a control signal generation unit, potential control unit, and fuse output unit that initializes and controls the potentials of both ends of a fuse after a power-up operation, enabling detection of whether the fuse is cut or not and maintaining the cutting state to prevent reconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuse is cut using laser beam to program the fuse circuit, then the fuse can be programmed to detect memory cell failures, but the cut fuse may subsequently undergo electrical and chemical migration causing reconnection
Solution Approach 1:
The patent applies preliminary anti-action by controlling the potentials of both ends of the fuse after cutting to prevent electrical and chemical migration before it can occur. The potential control unit actively maintains appropriate potential differences to counteract the migratory forces that would otherwise cause reconnection, thereby preventing the harmful effect before it manifests.
Solution Approach 2:
The patent implements preliminary action by initializing the fuse output unit and controlling potentials immediately after the fuse cutting operation. This ensures that the fuse is properly programmed and its ends are stabilized before the device undergoes subsequent manufacturing or operation, preventing migration-related reconnection issues from developing.
2Measurement precision
If the fuse cutting state is not properly controlled after power-up, then the circuit cannot detect whether the fuse is cut or not, but controlling potentials requires additional control circuits
Solution Approach 1:
The potential control unit serves multiple functions: it controls potentials to prevent migration, initializes the fuse output unit, and enables accurate fuse state detection. By combining these functions into a single control mechanism, the patent achieves precise measurement without proportionally increasing device complexity.
Solution Approach 2:
The fuse output unit is initialized automatically by the potential control unit in response to the power-up signal, without requiring separate initialization circuits. The control system serves itself by integrating the initialization function into the existing potential control mechanism, reducing overall circuit complexity while maintaining detection accuracy.
3Reliability
If fuse reconnection occurs during test operation at high temperature and high voltage, then the failure cannot be detected before packaging, but detecting and correcting such failures is difficult after packaging
Solution Approach 1:
The patent performs preliminary action by controlling fuse potentials and initializing the output unit before the device undergoes packaging. This ensures that fuse cutting states are stable and properly established prior to packaging, enabling failure detection to occur before the device is sealed, thereby avoiding the time loss and difficulty associated with post-packaging failure analysis.
Data Source
AI summary
A fuse circuit includes a control signal generation unit configured to generate a control signal that is enabled after a moment when a power-up signal is enabled, a potential control unit configured to control potentials of both ends of a fuse in response to the control signal, and a fuse output unit configured to be initialized in response to the power-up signal and output a fuse signal in response to whether the fuse is cut or not.