Semiconductor Memory Bit Line Direct Contact Structure
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Solution Overview
Problem
Semiconductor memory devices face challenges with increased resistance and reduced manufacturing margins, affecting their integration and reliability.
Innovation Solution
The semiconductor memory device design includes a cell active portion in a semiconductor substrate with a cell gate dielectric layer and electrode, doped regions, interlayer insulating layers, a data storage element, and a bit line that directly contacts the top surface of the data storage element, optimizing the structure to reduce resistance and enhance integration and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the semiconductor memory device is highly integrated, then the manufacturing margin is reduced, but the resistance of the memory cell increases
Solution Approach 1:
The bit line is configured to directly contact the top surface of the data storage element, transitioning from a lateral connection approach to a vertical/direct contact approach. This dimensional change in the connection path reduces the resistance between the bit line and data storage element, addressing the resistance increase problem caused by high integration density.
Solution Approach 2:
The patent establishes proper alignment margins between the bit line and data storage element during the manufacturing process. By pre-defining the spatial relationship and contact geometry, the design ensures low resistance connection is achieved without requiring additional process steps, thus resolving the contradiction between high integration and reliable low-resistance connections.
2Reliability
If the bit line directly contacts the top surface of the data storage element, then the resistance is reduced, but the alignment precision must be improved
Solution Approach 1:
The patent applies different quality requirements to different regions: the bit line width is optimized for direct contact at the contact point, while the overall alignment margin is designed with sufficient tolerance. The local contact area is precisely defined, but the broader alignment requirements remain relaxed, allowing high resistance performance without excessive manufacturing precision demands.
Solution Approach 2:
The patent optimizes the geometric parameters of the bit line and data storage element interface. By adjusting the contact area size, bit line width, and depth of contact, the design achieves low resistance connection while maintaining reasonable alignment margins. The parameter optimization allows the system to meet both low resistance and manufacturing precision requirements simultaneously.
Data Source
AI summary
A semiconductor memory device includes a cell gate dielectric layer and a cell gate electrode disposed in a gate recess region crossing a cell active portion of a substrate, first and second doped regions disposed in the cell active portion at both sides of the gate recess region, respectively, at least one interlayer insulating layer covering the substrate, a data storage element electrically connected to the second doped region through a contact plug penetrating the at least one interlayer insulating layer, a mold layer covering the data storage element, and a bit line disposed in a cell groove formed in the mold layer. The bit line is in direct contact with a top surface of the data storage element.