Dual Metallic Liners for 3D Memory Interconnects
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in effectively forming multilevel memory arrays with reliable interconnects, particularly in achieving uniform and stable metallic liners that prevent copper diffusion and reflow, which can lead to word line shorts and reduced isolation between bit lines.
Innovation Solution
The implementation of a structure with a metal portion embedded in dielectric material layers, featuring a first metallic liner on the bottom and sidewalls and a second metallic liner on the top surface, both differing in composition, ensures comprehensive contact with the metal portion and prevents copper diffusion, while an air-gap dielectric layer is used to enhance isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single metallic liner is used to contact the metal portion, then the structure is simpler, but copper diffusion and reflow cannot be effectively prevented
Solution Approach 1:
The single metallic liner is segmented into two distinct metallic liners: a first metallic liner contacting the bottom surface and lower sidewalls, and a second metallic liner contacting the top surface and upper sidewalls. Each liner can be composed of different materials optimized for their specific functions, allowing effective prevention of copper diffusion and reflow through coordinated action of multiple liner segments
Solution Approach 2:
Different regions of the metal portion are provided with different metallic liners tailored to local requirements. The first metallic liner at the bottom provides diffusion barrier functionality, while the second metallic liner at the top provides reflow prevention and additional barrier properties. This local differentiation optimizes protection against copper migration in different spatial zones
2Reliability
If metallic liners contact only partial surfaces of the metal portion, then the manufacturing process is simpler, but isolation between bit lines is reduced
Solution Approach 1:
The metallic liner coverage extends from partial surface contact to complete envelopment of the metal portion in three dimensions. The first metallic liner covers the bottom surface and lower sidewalls, while the second metallic liner covers the top surface and upper sidewalls, achieving全方位 (all-around) contact that prevents copper diffusion in all directional dimensions
3Reliability
If the first and second metallic liners have the same composition, then the manufacturing process is simpler, but the ability to prevent both diffusion and reflow is compromised
Solution Approach 1:
The first metallic liner and second metallic liner are composed of different materials selected to optimize specific functions. The first liner material is optimized for diffusion barrier properties at the bottom interface, while the second liner material is optimized for reflow prevention and oxidation resistance at the top interface, with each composition tailored to its local environmental conditions
Solution Approach 2:
The interconnect structure employs a composite arrangement of two different metallic liner materials, each contributing unique properties. This composite liner system combines the advantages of different materials to simultaneously achieve diffusion barrier functionality and reflow prevention, which would be difficult to accomplish with a single material
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively prevents copper diffusion and reflow, reduces word line shorts, and improves isolation between bit lines, thereby enhancing the reliability and performance of three-dimensional memory devices.
Implementation Method 1
a first metallic liner comprising a first metallic material and contacting a bottom surface of the metal portion and at least lower portions of sidewalls of the metal portion; and a second metallic liner comprising a second metallic material and contacting a top surface of the metal portion
Implementation Method 2
The first metallic material and the second metallic material differ in composition, and the first metallic liner and the second metallic liner contact an entirety of all surfaces of the metal portion
Data Source
AI summary
An opening is formed through at least one dielectric material layer. A first metallic liner is formed on a bottom surface and sidewalls of the opening by depositing a first metallic material. A metal portion including an elemental metal or an intermetallic alloy of at least two elemental metals is formed on the first metallic liner. A second metallic liner including a second metallic material is formed directly on a top surface of the metal portion. The first metallic material and the second metallic material differ in composition. The first metallic liner and the second metallic liner contact an entirety of all surfaces of the metal portion. The first and second metallic liners can protect the metal portion from a subsequently deposited dielectric material layer, which may be formed as an air-gap dielectric layer after recessing the at least one dielectric material layer.