Liner Layer Adhesion for Low-k Dielectric Interconnects
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Solution Overview
Problem
Low-k dielectric materials in semiconductor fabrication exhibit poor adhesion with metal barrier layers due to their inherent properties, such as low mechanical strength, high moisture absorption, and poor surface roughness, which can affect the reliability of interconnect structures during copper fabrication processes.
Innovation Solution
A liner layer with different materials on the sidewalls and bottom surfaces of openings in the low-k dielectric layer is formed to improve adhesion, comprising nitrogen-free materials on sidewalls and nitrogen-containing materials on bottom surfaces, followed by a conformal conductive barrier layer and conductive layer filling the openings, enhancing surface smoothness and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If low-k dielectric materials are used to reduce RC delay, then signal transferring performance is improved, but adhesion between the low-k dielectric layer and metal barrier layer deteriorates
Solution Approach 1:
A liner layer is introduced as an intermediary between the low-k dielectric layer and the metal barrier layer. This liner layer serves as a mediator that improves interfacial adhesion and provides a smoother surface for subsequent metal barrier layer deposition, resolving the adhesion problem caused by using low-k dielectric materials.
Solution Approach 2:
The surface properties of the interface between low-k dielectric and metal barrier layers are modified by introducing the liner layer. This changes the physical and chemical parameters of the interface, including surface roughness and composition, thereby improving adhesion while maintaining the low-k dielectric's electrical performance.
2Speed
If low-k dielectric materials with porosity are used to reduce dielectric constant, then RC delay is reduced, but surface roughness of sidewalls deteriorates
Solution Approach 1:
The liner layer acts as an intermediary that covers the rough sidewalls formed by porous low-k dielectric materials. It provides a smoother surface for metal barrier layer deposition, eliminating the adverse effect of sidewall roughness while preserving the low dielectric constant property.
Solution Approach 2:
The liner layer is selectively formed on the sidewalls and specific regions where surface smoothness is critical for adhesion. This local modification improves surface quality in specific areas without changing the overall porous structure and low-k properties of the dielectric material.
3Reliability
If low-k dielectric materials are used, then mechanical strength and moisture resistance deteriorate, but adhesion can be improved by liner layer
Solution Approach 1:
The liner layer serves as a protective intermediary that compensates for the poor adhesion inherent in low-k dielectric materials. It provides a stable interface for metal barrier layer attachment, thereby improving overall structural reliability despite the low-k material's intrinsic weaknesses.
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
The solution significantly improves the adhesion between low-k dielectric and diffusion barrier layers, leading to more reliable interconnect structures with reduced surface roughness and increased mechanical stability, addressing issues like line-to-line leakage, TDDB, RC delay, and electromigration.
Implementation Method 1
A liner layer is formed on sidewalls of the low-k dielectric layer exposed by the trench and via protions and a bottom surface exposed by the trench via portion
Data Source
AI summary
Interconnect structures are provided. An exemplary embodiment of an interconnect structure comprises a substrate with a low-k dielectric layer thereon. A via opening and a trench opening are formed in the low-k dielectric layer, wherein the trench opening is formed over the via opening and the via opening exposes a portion of the substrate. A liner layer is formed on sidewalls of the low-k dielectric layer exposed by the trench and via protions and a bottom surface exposed by the trench via portion, wherein the portion of the liner layer on sidewalls of the low-k dielectric layer exposed by the trench and via protions and the portion of the liner layer formed on a bottom surface exposed by the trench portion comprise different materials. A conformal conductive barrier layer is formed in the trench and via openings, covering the liner layer and the exposed portion of the substrate. A conductive layer is formed on the conductive barrier layer, filling in the trench and via openings.