Electrical Fuse Self-Test and Repair Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrical fuses in integrated circuits are not scalable for deep submicron technologies due to pitch limitations and lack self-test and repair capabilities, leading to increased manufacturing costs and yield loss due to faulty fuses.
Innovation Solution
A self-test and repair module is integrated into the electrical fuse circuit, utilizing multiplexers and an indication bit to compare intended data with stored faulty unit information, allowing for electrical programming and inversion of data to correct faulty bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical fuse is tested on ATE, then testing capability is provided, but manufacturing cost increases and test time increases
Solution Approach 1:
The patent implements self-test functionality where the electrical fuse circuit tests itself using built-in test circuits and control logic. The system can detect faulty fuses and generate repair information without requiring external ATE equipment, enabling the circuit to serve its own testing needs and eliminating the need for expensive external testing equipment.
Solution Approach 2:
The patent performs testing and fault detection before the actual programming operation. By pre-testing the electrical fuse circuit and identifying potential faults in advance, the system can prevent defective fuses from being programmed, thereby avoiding manufacturing defects and reducing the need for costly rework or discarding entire chips.
2Reliability
If ATE is used for testing, then electrical testing is performed, but repair capability is lost and yield decreases
Solution Approach 1:
The patent implements a feedback mechanism where the testing results and fault locations are fed back to the control logic. The system identifies which specific fuses are faulty and generates repair information that can be used to correct the defects. This closed-loop feedback enables the system to not only detect faults but also initiate repair processes, transforming the one-way ATE testing into an interactive repair-capable system.
Solution Approach 2:
The patent introduces an intermediary repair information storage and processing mechanism between the testing phase and the programming phase. This intermediary component stores fault location data and repair instructions, acting as a mediator that enables correction of faulty fuses without requiring complete chip discarding. The intermediary layer facilitates the transition from detection to repair.
3Ease of manufacture
If laser-fuse is used, then programming is achieved, but pitch scalability is limited by laser wavelength
Solution Approach 1:
The patent replaces the optical/laser-based programming mechanism with an electrical current-based mechanism. Instead of using laser beams to evaporate metal or polysilicon links, the system applies electrical current through the fuse link to induce resistance changes. This substitution of electrical mechanism for optical mechanism eliminates the wavelength limitation and enables scaling to deeper submicron technologies.
Solution Approach 2:
The patent changes the fundamental programming parameter from optical energy (laser wavelength) to electrical parameters (current density and duration). By controlling electrical current density and application time, the system achieves programming without being constrained by optical wavelength limitations, thereby enabling pitch scaling below the laser wavelength threshold.
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
Enables efficient testing and repair of electrical fuses, reducing manufacturing costs and improving product yield by allowing for the identification and correction of faulty bits within the circuit.
Implementation Method 1
When programming the electrical fuse, a high current density, typically 600 mA/um2 for the silicided polysilicon, is applied to the electrical fuse link for a certain period of time. The resistance of the electrical fuse will rise due to the electrical stress in its fuse link.
Data Source
AI summary
A circuit for testing and repairing a fuse device having a plurality of fuse units and being able to serially input and output data is disclosed, the circuit comprises a first multiplexer configured to select either a true or an inverted data for being stored in the fuse device, a second multiplexer configured to select either a true or an inverted data being read out from the fuse device, a storage unit configured to store information of faulty fuse units, and an indication bit being programmed to reflect a comparison between the data intended to be stored in the fuse device and the stored faulty unit information, wherein when the indication bit is at a first state, the first and second multiplexers select the true data, and when the indication bit is at a second state, the first and second multiplexers select the inverted data.