Asymmetric Bit Line Capping for Reliable Semiconductor Contacts
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Solution Overview
Problem
As semiconductor devices shrink in size for higher integration, the process difficulty and defect rate increase due to the challenges in manufacturing smaller circuit patterns, particularly in forming reliable contacts and maintaining structural integrity.
Innovation Solution
A semiconductor device design featuring a substrate with an active region, overlapping word and bit lines, a direct contact, and a buried contact, along with a spacer structure, where the bit line capping layer has asymmetric shapes to enhance connectivity and structural support, and a manufacturing method involving sequential material layer deposition and patterning to form these features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If circuit patterns are reduced in size for higher integration, then device integration is improved, but manufacturing precision deteriorates
Solution Approach 1:
The contact structure is divided into multiple segments: buried contact at the bottom, direct contact extending upward, and bit line capping layer on top. This segmentation allows each part to be optimized independently for its specific function while maintaining overall miniaturization
Solution Approach 2:
The contact structure transitions from two-dimensional planar patterns to three-dimensional vertical stacking. The direct contact extends vertically from the buried contact through multiple layers, utilizing the vertical dimension to achieve higher integration without compromising lateral pattern precision
2Length of moving object
If contact structures are miniaturized, then device size is reduced, but reliability deteriorates
Solution Approach 1:
The contact structure uses composite materials with different properties: doped polysilicon for the direct contact providing good electrical conductivity and mechanical strength, and silicon nitride for the bit line capping layer providing structural support and stress management. This composite approach maintains reliability while enabling miniaturization
Solution Approach 2:
The bit line capping layer is formed in advance before final bit line patterning. This preliminary action ensures the contact structure is established and protected early in the process, preventing damage during subsequent processing steps and improving contact formation reliability
3Stability of the object's composition
If bit line capping layer has asymmetric shape, then structural integrity is improved, but device complexity increases
Solution Approach 1:
The bit line capping layer has different widths at different locations: wider at the center where it covers the direct contact for enhanced structural support, and narrower at the sides. This local quality variation optimizes structural integrity at each specific location without requiring complex structures throughout the entire device
Data Source
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AI summary
A semiconductor device includes a substrate including an active region, a word line and a bit line that overlap the active region while crossing the active region, a bit line capping layer that is disposed on the bit line, a direct contact that connects the active region and the bit line, and a buried contact that is connected to the active region. Opposite sides of the bit line capping layer have asymmetric shapes.