DRAM Bit Line Isolation Seam Layout for Reliable Cell Connections
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The shrinking size of dynamic random access memory (DRAM) devices makes it increasingly difficult to establish reliable electrical connections between memory cells, with varying structural designs of transistors and capacitors complicating the manufacturing process.
Innovation Solution
A semiconductor memory device is fabricated with a substrate, bit lines, strip-shaped isolation structures, columnar isolation structures, and conductive plugs, where the conductive residue in the seam of the strip-shaped isolation structure is etched to prevent continuous electrical connections, and the same conductive material is used for both the conductive residue and plugs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of DRAM is continuously reduced to improve integration, then device density increases, but it becomes more difficult to build reliable electrical connections between memory cells
Solution Approach 1:
The isolation structure is segmented into a strip-shaped isolation structure with a seam that divides the conductive material distribution. This segmentation prevents continuous conductive paths from forming across the isolation structure, ensuring reliable electrical isolation between adjacent bit lines while maintaining small device dimensions for high density.
Solution Approach 2:
The seam in the strip-shaped isolation structure creates a localized region where conductive material is intentionally interrupted. This local modification of the isolation structure's conductive properties ensures that electrical connections are prevented only where needed (at the seam location) while maintaining proper isolation elsewhere, enabling reliable connections in scaled-down devices.
2Adaptability or versatility
If transistors and capacitors have varying structural designs to meet product requirements and cell density, then device functionality is optimized, but the manufacturing process becomes more complex
Solution Approach 1:
The strip-shaped isolation structure with a seam serves multiple functions: it provides electrical isolation between bit lines, controls conductive material distribution, and prevents unwanted electrical connections. This universal isolation structure can be applied across different memory cell designs (varying transistor and capacitor configurations) without requiring modification, simplifying the manufacturing process while maintaining design flexibility.
3Reliability
If conductive material is deposited to fill gaps and seams, then electrical connections are established, but continuous distribution of conductive material may create unnecessary electrical connections
Solution Approach 1:
The seam in the strip-shaped isolation structure extracts or removes the continuity of the isolation structure at a specific location. This intentional discontinuity prevents conductive material from forming continuous paths across the isolation structure, thereby eliminating unnecessary electrical connections while allowing controlled connections in the intended areas (conductive plugs between bit lines).
Data Source
AI summary
The present invention discloses a semiconductor memory device and a forming method thereof. The semiconductor memory device includes a substrate, a plurality of bit lines, a strip-shaped isolation structure, a conductive residue, a plurality of columnar isolation structures and a plurality of conductive plugs. The bit lines are located on the substrate and extend along the first direction. The strip-shaped isolation structure is located at the ends of the bit lines and extends along the second direction, and the strip-shaped isolation structure includes a seam. In particular, the conductive residue is disposed in the seam. The columnar isolation structures are separated from each other and disposed between the bit lines. The conductive plugs are separated from each other and disposed between the bit lines, in which the conductive plugs and the conductive residue include the same conductive material.