MOSFET Fuse Programming via Resistance Feedback
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Solution Overview
Problem
Existing one-time-programmable (OTP) memory elements, such as E-fuses in integrated circuits, face issues with uncontrolled programming and physical damage to adjacent structures, leading to leakage currents and reduced programming yield when scaled to smaller design geometries, due to suboptimal programming conditions.
Innovation Solution
Characterizing at least one MOS parameter of a MOS fuse and measuring its resistance after programming to compare against a reference value, ensuring accurate determination of logic states and reducing the risk of improper programming through redundant storage and sensing circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If E-fuse programming is performed using conventional methods, then the fuse link is destroyed to create high resistance, but uncontrolled programming or physical damage to adjacent structures occurs, resulting in leakage currents and reduced programming yield
Solution Approach 1:
The patent introduces a specialized sensing circuit as an intermediary between the fuse link and the programming control system. This sensing circuit includes a sense amplifier that detects resistance changes and control logic that regulates programming current, acting as a mediator to prevent uncontrolled programming and physical damage to adjacent structures while maintaining reliable fuse programming
Solution Approach 2:
The patent implements a feedback mechanism where the sensing circuit continuously monitors the resistance of the fuse link during programming. The sense amplifier detects resistance changes and feeds this information back to control logic, which adjusts the programming current accordingly. This feedback loop prevents overprogramming and physical damage, improving programming yield and reliability
2Productivity
If ICs are scaled to smaller design geometries, then integration density increases, but programming conditions become suboptimal, reducing programming yield and increasing programming time
Solution Approach 1:
The patent employs dynamic programming conditions that adapt to different design geometries. The sensing circuit and control logic automatically adjust programming parameters such as current magnitude and pulse duration based on the detected fuse characteristics. This dynamic adaptation enables optimal programming across various IC scales and technologies, reducing programming time while maintaining high yield in scaled geometries
3Reliability
If the fuse link cross section is reduced to achieve higher resistance state, then Joule heating increases during programming, but control over programming becomes more difficult
Solution Approach 1:
The patent replaces direct current control with a sensing-based control system. Instead of relying solely on mechanical or electrical current regulation, the system uses the sensing circuit to detect resistance changes and translates these into control signals. This substitution of direct mechanical/electrical control with a sensing-feedback system enables precise control of programming even in fuse links with reduced cross sections, maintaining manufacturing precision while achieving reliable high resistance states
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
This approach enhances programming reliability and yield by accurately determining the logic state of MOS fuses, reducing the occurrence of tail bits and improving overall programming efficiency in integrated circuits.
Implementation Method 1
The fuse link has a relatively small cross section, which results in Joule heating of the link during programming to convert the E-fuse to a high resistance state.
Implementation Method 2
The temperature gradient and the carrier flux causes electro- and stress-migration to take place and drive material (e.g., silicide, dopant, and polysilicon) away from the fuse link.
Implementation Method 3
The temperature gradient and the carrier flux causes electro- and stress-migration to take place and drive material (e.g., silicide, dopant, and polysilicon) away from the fuse link.
Data Source
AI summary
At least one MOS parameter of a MOS fuse is characterized to provide at least one MOS parameter reference value. Then, the MOS fuse is programmed by applying a programming signal to the fuse terminals so that programming current flows through the fuse link. The fuse resistance is measured to provide a measured fuse resistance associated with a first logic value. A MOS parameter of the programmed MOS fuse is measured to provide a measured MOS parameter value. The measured MOS parameter value is compared to the reference MOS parameter value to determine a second logic value of the MOS fuse, and a bit value is output based on the comparison.