Bit Line Air Spacer Structure for Lower Parasitic Capacitance
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Solution Overview
Problem
As semiconductor devices become smaller and more integrated, parasitic capacitance increases, degrading the operation performance of these devices.
Innovation Solution
The semiconductor device incorporates an air spacer in the insulating spacer structure covering the bit line, which helps reduce parasitic capacitance by creating a gap between the bit line and the buried contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If high degree of integration is implemented to make electronic devices smaller, then device size is reduced, but parasitic capacitance increases
Solution Approach 1:
An air spacer structure is introduced as an intermediary element between the bit line and the buried contact. This air spacer creates a physical gap filled with air (low dielectric constant material) that mediates the electrical interaction between the bit line and buried contact, thereby reducing parasitic capacitance while maintaining the high integration layout
Solution Approach 2:
The air spacer is selectively positioned only in critical regions where parasitic capacitance most significantly impacts performance - specifically between the bit line and buried contact. This localized application of the air gap strategy reduces parasitic capacitance where needed without compromising overall device integration and functionality
2Productivity
If design rule is reduced to increase integration, then device density increases, but parasitic capacitance degrades operation performance
Solution Approach 1:
The air spacer acts as a mediator that allows the bit line and buried contact to be placed in close proximity (enabling high density) while simultaneously preventing harmful electrical interaction (maintaining performance). The air-filled gap provides electrical isolation that preserves signal integrity even when design rules are reduced
3Reliability
If air spacer is introduced to reduce parasitic capacitance, then operation performance is improved, but device complexity increases
Solution Approach 1:
The spacer structure is segmented into multiple functional portions: a first spacer portion extending from the bit line sidewall, and a second spacer portion extending from the buried contact sidewall. This segmentation allows each portion to be formed through separate process steps with optimized dimensions, managing structural complexity while achieving the performance benefit of reduced parasitic capacitance
Data Source
AI summary
A semiconductor device includes bit line structures disposed on a substrate, each bit line structure comprising a bit line and an insulating spacer structure, buried contacts which fill lower portions of spaces between bit line structures in the substrate, and landing pads which fill upper portions of the spaces, extend from upper surfaces of the buried contacts to upper surfaces of the bit line structures, and are spaced apart from each other by insulating structures. A first insulating structure is disposed between a first landing pad and a first bit line structure. The first insulating structure includes a sidewall extending along a sidewall of the first landing pad toward the substrate. In a direction extending toward the substrate, the sidewall of the first insulating structure gets closer to a first sidewall of the first bit line structure.