PCRAM Cell with Same-Conductivity Selector for Write Disturb
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Solution Overview
Problem
Phase-change random access memory (PCRAM) devices experience write disturb in non-selected and half-selected cells due to voltage relationships, leading to potential write errors in selected cells, necessitating a solution to prevent these issues while maintaining write efficiency.
Innovation Solution
The semiconductor storage device incorporates a memory cell configuration with a selector and memory element of the same conductivity type, utilizing the Peltier effect to concentrate current and reduce switching voltages, thereby preventing write disturb in non-selected cells and improving write efficiency in selected cells by optimizing electrode diameters and biasing methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If standard memory cell configuration is used, then device complexity is low, but write disturb occurs in non-selected and half-selected cells
Solution Approach 1:
The memory cell is segmented into two distinct functional components: a memory element for data storage and a selector for current control. This segmentation allows the selector to specifically target and control current flow to selected cells only, preventing write disturb in non-selected and half-selected cells while maintaining a relatively simple overall structure.
2Reliability
If higher current or voltage is applied to selected cell to ensure write accuracy, then write error is prevented, but write disturb occurs in non-selected and half-selected cells
Solution Approach 1:
By assigning opposite conductivity types to the memory element and selector, the patent creates local electrical characteristics that enable the selector to block current in non-selected cells even when high voltage is applied to the selected cell. This local quality differentiation allows high current flow to the selected cell for accurate writing while preventing current leakage to adjacent cells.
Solution Approach 2:
The selector serves as an intermediary that controls and regulates current flow based on selection signals. It ensures that high current or voltage applied to the selected cell for accurate writing does not propagate to non-selected or half-selected cells, thus preventing write disturb while maintaining write accuracy.
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 configuration effectively reduces switching voltages for selected cells, prevents write errors, and minimizes current flow into non-selected and half-selected cells, enhancing write efficiency and preventing write disturb across the memory array.
Implementation Method 1
utilizing the Peltier effect to concentrate current and reduce switching voltages
Data Source
AI summary
According to one embodiment, a semiconductor includes a first wiring, a second wiring, a first electrode, a second electrode and a memory cell. The first wiring extends in a first direction. The second wiring extends in a second direction crossing the first direction. The first electrode is connected to the first wiring. The second electrode is connected to the second wiring. The memory cell is arranged between the first electrode and the second electrode. The memory cell includes a memory element electrically connected to the first electrode, and a selector provided between the memory element and the second electrode and electrically connected to the second electrode, and the memory element and the selector are of a same conductivity type.