DRAM Field Region Conformal Layer for Row Hammer Mitigation
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Solution Overview
Problem
Dynamic random-access memory (DRAM) devices experience data corruption due to 'row hammer failure' caused by repeated access to a single row of memory cells, leading to charge migration and data bit failure, especially in devices with smaller geometries like the 32 nanometer process.
Innovation Solution
A DRAM cell array design that includes trenches in active and field regions with specific dielectric and conductive layers, where a second conformal layer with a different composition in the field region acts as a work function layer to reduce interference from neighboring active regions, thereby minimizing data bit failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If repeated access to a single row of memory cells is performed, then processing speed and access frequency are improved, but charge migration occurs causing data corruption in non-accessed rows
Solution Approach 1:
A conformal layer with specific work function is introduced as an intermediary between the bit line contact and the active region. This intermediary layer prevents charge migration from the accessed row to the non-accessed row by acting as a barrier, thus maintaining data integrity while allowing high-speed access operations to continue
Solution Approach 2:
The work function of the conformal layer is specifically engineered to have a value that creates an energy barrier against charge migration. By changing the material composition or thickness parameters of the conformal layer, the work function is optimized to prevent charge leakage while maintaining electrical connectivity for normal read/write operations
2Quantity of substance
If smaller geometries are used to increase storage density, then storage capacity is improved, but row hammer failure probability increases
Solution Approach 1:
The conformal layer with specific work function is selectively applied in the field region adjacent to the active region, creating a localized protection zone. This local quality enhancement prevents charge migration at the critical interface without affecting the overall small geometry dimensions, thus maintaining high storage density while reducing row hammer failures
Solution Approach 2:
The memory structure is segmented into distinct regions with different material properties: the active region for data storage, the field region for isolation, and the conformal layer as a protective interface. This segmentation allows each region to be optimized independently, enabling small geometries for high density while incorporating protective features to reduce failure probability
Data Source
AI summary
Embodiments of the present disclosure generally relate to a storage device. More specifically, embodiments described herein generally relate to a dynamic random-access memory and the method of making thereof. In one embodiment, a cell array includes at least an active region and a field region adjacent to the active region. The active region includes at least one trench, a dielectric layer disposed in the trench, a first conformal layer disposed on the dielectric layer, and a conductive material disposed on the first conformal layer. The field region includes a trench, a dielectric layer disposed in the trench, a second conformal layer disposed on the dielectric layer, and a conductive material disposed on the second conformal layer. The second conformal layer has a different composition than the first conformal layer.