Reprogrammable eFuse Design Using Differential Resistance Tuning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current electrical programmable fuses (eFuses) are not reprogrammable, limiting their use in applications requiring reversible data writing and erasing, such as EEPROMs, where they must be written, read, and erased in a reprogrammable manner.
Innovation Solution
A reprogrammable eFuse design that uses a pair of eFuses with differential resistance tuning, where a first eFuse is programmed with a smaller incremental current and a second eFuse with a larger incremental current, allowing for multiple cycles of programming and sensing with a sensing amplifier to determine logical states, enabling reprogrammability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional eFuse technology is used with high DC current pulse to program fuses, then programming capability is achieved, but reprogrammability is lost
Solution Approach 1:
The patent divides the fuse programming into two distinct phases: an initial high-current pulse phase that sets the basic fuse state, and subsequent low-current programming phases that enable reprogrammability. This segmentation allows the fuse to be programmed multiple times while maintaining reliability, as each phase serves a specific function in the programming process.
Solution Approach 2:
The patent introduces dynamic current control during the programming process. The current magnitude is adjusted based on the programming stage: high current for initial programming and low current for subsequent reprogramming. This dynamic adjustment enables the fuse to transition between programmed and unprogrammed states multiple times, achieving reprogrammability while maintaining the reliability of permanent programming when needed.
2Productivity
If high DC current pulse is applied to program eFuse, then fuse programming is achieved, but energy consumption increases
Solution Approach 1:
The patent employs periodic action by alternating between high-current initial programming pulses and low-current subsequent programming pulses. This periodic pattern allows fast initial programming while minimizing overall energy consumption, as the high current is applied only briefly during the initial set and then replaced by lower current operations for any reprogramming.
Solution Approach 2:
The patent performs preliminary action by using a high current pulse during the initial programming phase to quickly establish the fuse state. Once this preliminary programming is complete, subsequent operations use much lower current, significantly reducing the total energy consumption while maintaining high productivity for the initial programming task.
3Adaptability or versatility
If single fuse structure is used, then simplicity is maintained, but reprogrammability cannot be achieved
Solution Approach 1:
The patent applies universality by designing a fuse structure that serves multiple functions: it can be programmed initially with high current, reprogrammed with low current, and maintained in its state. This multi-functional design achieves reprogrammability without requiring entirely new fuse structures, thereby limiting the increase in device complexity while gaining the versatility needed for repeated programming operations.
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 multiple cycles of programming and reading, maintaining control over resistance changes until high resistance values are reached, making eFuses suitable for applications requiring reprogrammability like EEPROMs.
Implementation Method 1
A DC current pulse of approximately 10 mA in amplitude and duration of 200 μsec is required to program the fuse 110. This high current programs the fuse 110 by dynamically increasing the resistance of the polysilicon link.
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
An apparatus and method for providing a reprogrammable electrically programmable fuse (eFuse) are provided. With the apparatus and method, a pair of eFuses are provided coupled to programming current sources and sensing current sources. When the pair of eFuses is to be programmed, a first programming current is applied to a first eFuse to thereby increase the resistance of the first eFuse by an incremental amount. When the pair of eFuses is to be returned to an unprogrammed state, a second programming current source is applied to a second eFuse to thereby increase a resistance of the second eFuse to be greater than the resistance of the first eFuse. When the sensing current is applied to the eFuses, a difference in the resulting voltages across the eFuses is identified and used to indicate whether the reprogrammable eFuse is in a programmed state or unprogrammed state.