Multilayer RRAM Read Stability via Preliminary Anti-Action
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Resistance-change nonvolatile memory devices face instability during reading operations due to resistance value changes caused by read voltages, leading to potential issues with subsequent writing operations and accurate foaming determination.
Innovation Solution
A resistance-change nonvolatile memory device with a multilayer memory cell array, where each memory cell has a selection element, a first electrode, a first resistance change layer, and a second resistance change layer, with the read circuit applying specific voltages to prevent resistance value increases during reading, ensuring stable operation by controlling the polarity and direction of electric current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a read voltage is applied to perform a reading operation, then the resistance state can be detected, but the resistance value of the resistance change element changes due to read disturbance
Solution Approach 1:
The patent applies a preliminary counter-voltage to the resistance change element before the reading operation to pre-compensate for the expected resistance increase caused by read disturbance. This preliminary anti-action prevents the resistance value from changing during the reading operation, thereby maintaining both measurement precision and reliability simultaneously
2Ease of operation
If the resistance value changes due to read disturbance, then reading can be performed, but subsequent writing operations become problematic
Solution Approach 1:
By applying a counter-voltage that compensates for read disturbance before reading, the patent prevents resistance value changes that would otherwise interfere with subsequent writing operations. This ensures both reading capability and writing reliability are maintained
3Measurement precision
If read voltage is applied to detect resistance state, then data can be read, but the read window for resistance-state determination becomes narrow
Solution Approach 1:
The patent applies a preliminary counter-voltage to prevent resistance increase during reading, thereby maintaining the original resistance states and expanding the read window margin for more reliable resistance-state determination
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
The solution enables stable reading operations by preventing resistance value increases, ensuring sufficient voltage for writing operations and expanding the read window for resistance-state determination, thus enhancing the reliability of the memory device.
Implementation Method 1
the read circuit applies a voltage to the selected memory cell to perform the reading operation, which causes the second electrode to become positive with reference to the first electrode in the selected memory cell
Implementation Method 2
A resistance change element has properties in which its resistance value changes reversibly in accordance with an electrical signal, and is also capable of storing data corresponding to this resistance value in a nonvolatile manner
Data Source
AI summary
A selection circuit that selects a memory cell from a memory cell array and a read circuit for reading a resistance state of a resistance change element in the selected memory cell are provided. In memory cells of odd-numbered-layer and even-numbered-layer memory cell arrays that constitute a multilayer memory cell array, each memory cell in any of the layers has a selection element, a first electrode, a first resistance change layer, a second resistance change layer, and a second electrode that are disposed in the same order. Whether the selected memory cell is located in any layer of the multilayer memory cell array, the read circuit applies a voltage to the selected memory cell to perform the reading operation. The voltage applied to the selected memory cell causes the second electrode to become positive with reference to the first electrode in the selected memory cell.