Self-Aligned Contact Pads for Semiconductor Integration Density
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Solution Overview
Problem
The increasing integration of semiconductor devices leads to challenges in stably separating bit lines and lower electrodes of capacitors, resulting in increased parasitic capacitance and insufficient contact margins, which complicates the bit line forming process.
Innovation Solution
The semiconductor device design includes a substrate with field areas defining active regions, buried gates, gate capping fences, bit line trenches, insulator structures, and contact pads self-aligned with the gate capping fences, allowing for the formation of damascene bit lines and reducing contact misalignment by ensuring stable separation between bit lines and lower electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the degree of integration of semiconductor devices is increased, then the design rule of components is reduced, but it becomes difficult to stably separate bit lines and lower electrodes of capacitors, increasing parasitic capacitance
Solution Approach 1:
The device structure is segmented into distinct regions with gate capping fences creating physical separation between the bit line area and capacitor area. The gate capping fence divides the substrate into a bit line region and a capacitor region, ensuring stable separation even as overall device dimensions are reduced for higher integration.
Solution Approach 2:
The gate capping fence acts as an intermediary structure between the bit line and the lower electrode of the capacitor. This intermediate element provides the necessary separation and defines the contact margin, preventing direct interaction that would increase parasitic capacitance while allowing both components to exist in a highly integrated layout.
2Productivity
If the degree of integration is increased, then component density improves, but the contact margin between active area and lower electrode becomes insufficient, complicating the bit line forming process
Solution Approach 1:
The gate capping fence is formed in advance during the gate formation process, before the bit line formation process. This preliminary structure pre-defines the contact margin and separation boundaries, making the subsequent bit line formation process simpler and more reliable even at high integration densities.
Solution Approach 2:
The gate capping fence automatically defines the contact margin and separation boundaries through its geometric relationship with the active area and bit line trench. This self-aligning feature eliminates the need for additional alignment steps or complex process controls, allowing the structure to serve its own alignment function.
3Productivity
If design rules are reduced for higher integration, then device density increases, but parasitic capacitance between bit line and lower electrode increases
Solution Approach 1:
The harmful parasitic capacitance is eliminated by extracting or removing the direct coupling path between the bit line and lower electrode. The gate capping fence physically separates these two components, preventing the formation of parasitic capacitance even when they are in close proximity for high density integration.
Data Source
AI summary
A semiconductor device includes a substrate having a field area that defines active areas, gate trenches in the substrate and extending in a first direction, a buried gate in a respective gate trench, gate capping fences in a respective gate trench over a respective buried gate, the gate capping fences protruding from top surfaces of the active areas and extending in the first direction, bit line trenches in the gate capping fences, a respective bit line trench crossing the gate capping fences and extending in a second direction perpendicular to the first direction, an insulator structure on inner walls of a respective bit line trench, bit lines and bit line capping patterns stacked on the insulator structures in a respective bit line trench, contact pads self-aligned with the gate capping fences and on the substrate between the adjacent bit lines, and a lower electrode of a capacitor on a respective contact pad.