Cell Contact Air Gap Structure for Lower Parasitic Capacitance
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Solution Overview
Problem
Semiconductor devices face challenges in scaling down while maintaining improved quality, yield, performance, and reliability, particularly due to increased parasitic capacitance between conductive features.
Innovation Solution
Incorporating air gaps in the semiconductor device design, specifically through the formation of a cell contact structure with a cell contact bottom conductive layer surrounded by a sacrificial segment and a cell contact top sealing layer, and additional air gaps between bit line spacers, to reduce parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semiconductor device dimensions are scaled down to increase computing ability, then device density and computing power are improved, but parasitic capacitance between conductive features increases
Solution Approach 1:
An air gap is introduced as an intermediary insulating structure between the bit line structure and cell contact structure. This air gap acts as a mediator that reduces the parasitic capacitance coupling between these conductive features while allowing the device dimensions to be scaled down for improved computing ability.
Solution Approach 2:
The air gap is selectively formed only in specific regions where parasitic capacitance reduction is most critical - between the bit line structure and cell contact structure. This localized approach reduces parasitic capacitance where it most impacts performance without requiring global redesign of the entire device structure.
2Reliability
If air gaps are incorporated to reduce parasitic capacitance, then device performance is improved, but device structure and fabrication process become more complex
Solution Approach 1:
A sacrificial layer is formed beforehand in the opening before depositing the bit line structure. This preliminary placement of the sacrificial layer enables subsequent formation of the air gap through selective removal, simplifying the overall process compared to attempting to create the air gap through more complex direct fabrication methods.
Solution Approach 2:
The sacrificial layer is temporarily introduced and then completely removed after serving its purpose of defining the air gap space. This extraction of the sacrificial material leaves behind the desired air gap structure without requiring complex in-situ air gap formation techniques.
3Object-affected harmful factors
If air gaps are formed using sacrificial layers and punch etching, then parasitic capacitance is reduced, but manufacturing process complexity increases
Solution Approach 1:
The sacrificial layer is conformally deposited to automatically self-align with the opening structure, and the punch etch process automatically removes it to form the air gap. This self-service approach eliminates the need for additional alignment steps or complex patterning processes that would otherwise be required to create the air gap structure.
Data Source
AI summary
The present application discloses a semiconductor device and a method for fabricating the semiconductor device. The semiconductor device includes a substrate; a drain positioned in the substrate; a top dielectric layer positioned on the substrate; a cell contact structure including a cell contact bottom conductive layer positioned in the top dielectric layer and on the drain, a cell contact top conductive layer positioned in the top dielectric layer and on the cell contact bottom conductive layer, and a cell contact top sealing layer positioned in the top dielectric layer, on the cell contact bottom conductive layer, and surrounding the cell contact top conductive layer; and a first air gap positioned in the top dielectric layer and surrounding the cell contact bottom conductive layer.