DRAM Contact Air-Gap Structure for Lower RC Delay
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Solution Overview
Problem
The shrinking critical dimension of dynamic random-access memory (DRAM) devices leads to increased capacitance between bit lines and contacts, resulting in slower resistance-capacitance delay (RC delay) and reduced operating speed.
Innovation Solution
Incorporating air gaps surrounding the contacts to reduce capacitance between bit lines and contacts, achieved through a manufacturing process involving the formation of sacrificial layers, etching, and planarization to create air gaps that encapsulate conductive structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the critical dimension of DRAM is shrunk to achieve lightweight and compact design, then the device size is reduced, but the capacitance between bit lines and contacts increases leading to slower RC delay
Solution Approach 1:
Air gaps are introduced as intermediary structures between the bit lines and contacts. These air gaps act as mediators that reduce the capacitance coupling between bit lines and contacts by providing electrical isolation through the low-dielectric-constant air medium, thereby reducing RC delay and improving operating speed while maintaining the scaled-down device dimensions
Solution Approach 2:
The patent utilizes air gaps (porous structures) surrounding the contacts to reduce parasitic capacitance. The air-filled spaces provide electrical isolation between conductive elements, reducing the capacitive coupling effect that would otherwise slow down signal propagation in the scaled device
2Speed
If air gaps are introduced to reduce capacitance, then operating speed increases, but device complexity increases due to additional manufacturing steps
Solution Approach 1:
A sacrificial layer is formed in advance around the contacts before finalizing the contact structure. This preliminary action allows the sacrificial material to be subsequently removed to create air gaps, simplifying the overall process by pre-positioning the structure that will define the air gap boundaries rather than attempting to create air gaps directly through complex lithography or deposition techniques
Data Source
AI summary
Provided is a memory device including a substrate, a plurality of contacts, and a plurality of air gaps. The substrate has a plurality of active areas. The contacts are respectively disposed on ends of the active areas. The air gaps respectively surround the sidewalls of the contacts.