MRAM Contact Resistance Layout for Uniform Write Current
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Solution Overview
Problem
In magnetoresistive random access memory (MRAM) devices, the variation in resistance value of wiring paths due to differing lengths of word and bit lines can lead to misreading and breakdown errors, affecting data reliability and storage integrity.
Innovation Solution
The memory device employs a configuration where the resistance value of contact plugs varies based on their proximity to selection circuits, with higher resistance values near selection circuits and lower values farther away, to stabilize the resistance value of wiring paths and reduce misreading errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the wiring path length is increased to connect more memory cells, then the memory capacity is improved, but the resistance value of the wiring path increases causing misreading errors
Solution Approach 1:
The patent applies local quality by making the resistance value of contact plugs position-dependent. Contact plugs connected to memory cells farther from the selection circuit are given lower resistance values, while those closer have higher resistance values. This local variation in resistance compensates for the cumulative resistance increase in longer wiring paths, maintaining uniform total resistance across all memory cell connections and eliminating misreading errors.
2Ease of manufacture
If uniform resistance values are assigned to all contact plugs, then the manufacturing process is simplified, but misreading errors occur due to wiring path resistance variations
Solution Approach 1:
The patent implements parameter changes by varying the resistance value parameter of contact plugs based on their positional parameters. Specifically, the resistance value is changed systematically according to the distance from the selection circuit, creating a gradient distribution that compensates for wiring path variations. This approach maintains manufacturing simplicity while significantly improving data retrieval accuracy by eliminating misreading errors.
3Reliability
If the resistance value of contact plugs is increased to compensate for long wiring paths, then the total resistance is stabilized, but the current density increases causing potential damage
Solution Approach 1:
The patent applies local quality by distributing the resistance compensation function across individual contact plugs based on their specific positional requirements. Each contact plug's resistance is optimized for its local wiring path length, preventing excessive current density at any single point. This localized optimization stabilizes total resistance while avoiding the harmful effects of uniformly high resistance values.
Data Source
AI summary
According to one embodiment, a memory device includes: a first memory cell; a second memory cell; a first circuit configured to supply a write current to the first memory cell and the second memory cell; a first wiring coupled to the first circuit; a first electrode configured to electrically couple the first memory cell to the first wiring; and a second electrode configured to electrically couple the second memory cell to the first wiring. A length of the first wiring from the first circuit to the first electrode is smaller than a length of the first wiring from the first circuit to the second electrode. A resistance value of the first electrode is higher than a second resistance value of the second electrode.