Self-Terminating OTP Memory Fuse Programming via Feedback
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Solution Overview
Problem
One-time programmable (OTP) memories face challenges in reliably programming silicided polysilicon fuses due to variations in process, voltage, and temperature, leading to inconsistent resistance changes and increased costs from frequent incorrect programming and reliability issues.
Innovation Solution
A circuit design that includes a logic circuit, a fuse core, and a sense circuit, which applies a constant current and monitors the sense voltage to self-terminate programming when the desired resistance threshold is reached, allowing for faster programming and accounting for variations in process and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed voltage is applied across the fuse for a predefined period to program it, then the fuse can be programmed to store data, but the programming time must be precisely controlled to avoid re-flow or incomplete programming
Solution Approach 1:
The patent implements a feedback mechanism where a sense circuit continuously monitors the resistance of the fuse during programming. The sense amplifier compares the sense voltage (across the fuse) to a reference voltage and generates a sense signal that feeds back to the programming circuit. This feedback allows the circuit to detect when the fuse has reached the desired resistance level and automatically terminate programming, preventing re-flow while ensuring complete programming. The feedback loop dynamically adjusts programming duration based on real-time fuse state, resolving the contradiction between reliable programming and time efficiency.
Solution Approach 2:
The fuse programming process is made self-terminating through the feedback mechanism. The sense circuit automatically detects when the fuse reaches the target resistance state and signals the programming circuit to stop applying voltage. This self-service approach eliminates the need for external timing control and ensures that programming terminates precisely when the fuse is properly programmed, avoiding both incomplete programming and re-flow issues while optimizing programming duration.
2Reliability
If multiple redundant OTP memory cells are used to account for programming failures, then the reliability of data storage is improved, but the device complexity and cost increase
Solution Approach 1:
The feedback mechanism in the patent enables single-cell reliable programming by automatically detecting and preventing programming failures. The sense circuit monitors each fuse's resistance in real-time and provides feedback to terminate programming at the optimal moment, eliminating the need for redundant cells to compensate for programming errors. This feedback-based quality control reduces device complexity while maintaining or improving data storage reliability compared to traditional approaches requiring multiple redundant cells.
3Manufacturing precision
If the programming time is extended to ensure complete fuse programming, then programming completeness is improved, but the risk of re-flow and programming errors increases
Solution Approach 1:
The feedback mechanism provides real-time monitoring of fuse resistance during programming, allowing the circuit to detect when the desired resistance level is achieved and automatically terminate voltage application. This prevents excessive programming time that could cause re-flow, while ensuring complete programming by continuously verifying fuse state. The feedback loop dynamically balances programming duration to achieve manufacturing precision without introducing harmful re-flow effects.
Solution Approach 2:
The fuse programming system is self-regulating through the sense circuit that automatically detects programming completion and terminates voltage application. This self-service mechanism ensures programming completeness by monitoring until the fuse reaches target resistance, while simultaneously preventing re-flow by stopping voltage application at the optimal moment. The self-terminating approach eliminates the trade-off between extended programming time and re-flow risk.
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 enables reliable, self-terminating programming of OTP memory cells, reducing the risk of re-flow and allowing for faster programming times, even across a range of temperatures, thereby improving the accuracy and efficiency of OTP memory cell programming.
Implementation Method 1
The current source provides a substantially constant current through a programmable fuse in the fuse core at a value set by the voltage reference, eventually causing the desired highest resistance phase transition in the fuse
Implementation Method 2
A circuit design that includes a logic circuit, a fuse core, and a sense circuit, which applies a constant current and monitors the sense voltage to self-terminate programming when the desired resistance threshold is reached
Data Source
AI summary
A one-time programmable memory includes a first one-time programmable memory cell including a fuse core having an input terminal for receiving a trim signal, an output terminal for providing a sense signal, and a fuse. The fuse core conducts current through the fuse in response to the trim signal. The one-time programmable memory cell also includes a sense circuit having an input terminal coupled to the output terminal of the fuse core, and an output terminal for providing a termination signal, and a logic circuit having a first input terminal for receiving a program enable signal, a second input terminal for receiving a data signal, a third input terminal coupled to the output terminal of the sense circuit for receiving the termination signal, and an output terminal coupled to the input terminal of the fuse core for providing the trim signal.