DRAM Bit Line Fabrication via Segmented Buried Gate and Direct Contact Isolation
Solution Overview
Problem
Current DRAM devices with buried gate structures face limitations in fabrication capability, affecting their performance and reliability due to challenges in integrating higher density and miniaturization.
Innovation Solution
A method for fabricating semiconductor devices involves forming a first bit line structure on a substrate, adjacent spacers, an interlayer dielectric layer, and a storage node contact isolation structure, which directly contacts the bit line and spacer, enhancing the fabrication process for DRAM devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DRAM units with planar gate structures are used, then fabrication is simpler, but carrier channel length is shorter leading to increased capacitor leakage
Solution Approach 1:
The bit line structure is segmented into multiple layers including a first bit line structure and a second bit line structure formed at different levels. This segmentation allows the buried gate to extend longer along the carrier channel while maintaining manageable fabrication processes for each individual layer
Solution Approach 2:
The invention transitions from a planar gate structure to a buried gate structure by moving the gate into the substrate dimension. This dimensional change enables the gate to extend longer along the carrier channel (improving reliability) while the multi-layer bit line approach keeps fabrication complexity manageable
2Productivity
If DRAM units are designed for higher integration and density, then miniaturization is achieved, but fabrication capability limitations affect performance and reliability
Solution Approach 1:
The fabrication process is segmented into distinct stages with each bit line structure formed separately. This allows standard fabrication processes to be applied to each layer individually, achieving high integration density without exceeding manufacturing precision capabilities
Solution Approach 2:
The first bit line structure is formed preliminarily before the second bit line structure. This preliminary action allows subsequent structures to be built upon established foundations, enabling higher integration while maintaining manufacturing precision through controlled sequential fabrication
3Ease of manufacture
If storage node contact isolation structure contacts bit line and spacer directly, then fabrication process is enhanced, but structure complexity increases
Solution Approach 1:
The storage node contact isolation structure merges the functions of isolation and contact formation by directly contacting both the bit line structure and spacer. This consolidation simplifies the fabrication process by reducing the number of separate structures needed, even though the contact geometry becomes more complex
Data Source
AI summary
A method for fabricating semiconductor device includes the steps of: forming a first bit line structure on a substrate; forming a first spacer adjacent to the first bit line structure; forming an interlayer dielectric (ILD) layer adjacent to the first spacer; removing part of the ILD layer and part of the first spacer to expose a sidewall of the first bit line structure; and forming a first storage node contact isolation structure adjacent to the first bit line structure, wherein the first storage node contact isolation structure contacts the first bit line structure and the first spacer directly.