Vertical Diffusion Barriers in IC Interconnects for Electromigration Resistance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

As integrated circuits are scaled to smaller dimensions, their interconnects become increasingly susceptible to electromigration, leading to mechanical stress, delamination, and electrical shorts due to the accumulation of metal atoms under unidirectional electrical current, which existing solutions fail to adequately address.

Innovation Solution

The implementation of vertical diffusion barriers within the interconnect structure, where the liner material of the via extends completely through the metal line, acting as a diffusion blocking boundary to suppress mass transport along grain boundaries and utilize the Blech effect for electromigration resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If integrated circuits are scaled to smaller dimensions to increase density and performance, then device speed and circuit functionality are improved, but interconnects become more susceptible to electromigration effects

Engineering Contradiction:

Improvedevice speed and circuit functionalityVSAvoidelectromigration resistance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The via is divided into multiple segments: an upper via portion, a lower via portion, and an intermediate portion extending through the metal line. This segmentation allows the intermediate portion to act as a diffusion barrier that interrupts grain boundary pathways and creates mechanical backflow to counteract electromigration-induced mass transport

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The intermediate portion of the via, filled with barrier material, serves as an intermediary element between the upper and lower via portions. It mediates the electromigration effect by creating a diffusion barrier that blocks metal atom transport along grain boundaries while maintaining electrical connectivity through the metal line

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If via depth is increased to improve via fill control and reduce void formation, then manufacturing precision is improved, but stress gradients and electromigration effects are exacerbated

Engineering Contradiction:

Improvevia fill controlVSAvoidstress gradients and electromigration

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The via structure is segmented into three distinct portions with different functions: the upper and lower portions provide electrical connectivity, while the intermediate portion acts as a stress-relief and diffusion-barrier element. This segmentation allows each portion to be optimized independently for its specific function

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the via are assigned different local qualities: the intermediate portion is filled with barrier material to create a diffusion barrier, while the upper and lower portions are filled with conductive material for electrical connectivity. This local differentiation allows the structure to simultaneously reduce stress gradients and maintain electrical performance

Inventive Principle:

Principle #3Local quality

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 approach effectively suppresses electromigration-induced mass flow by creating a mechanical backflow, significantly improving the lifetime of integrated circuit chips by interrupting continuous grain boundary pathways and reducing stress gradients, thereby enhancing electromigration resistance.

Implementation Method 1

the one or more vertical diffusion barriers correspond to a liner material of a via formed above the metal line... suppressing mass transport along grain boundaries

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

Electromigration is a term referring to the phenomenon of mass transport of metallic atoms... as a result of unidirectional or DC electrical current conduction therethrough

Methodology Applied

Scientific EffectElectromigration:

Implementation Method 3

utilize the Blech effect for electromigration resistance... creating a mechanical backflow, significantly improving the lifetime

Methodology Applied

Scientific EffectMechanical backflow:

Implementation Method 4

interrupting continuous grain boundary pathways and reducing stress gradients, thereby enhancing electromigration resistance

Methodology Applied

Scientific EffectStress gradient reduction:

Data Source

PatentUS8232646B2Interconnect structure for integrated circuits having enhanced electromigration resistance

Publication Date: 2012.07.31 GLOBALFOUNDRIES US INC

AI summary

An interconnect structure for an integrated circuit (IC) device includes a metal line formed within a dielectric layer, the metal line having one or more vertical diffusion barriers therein; wherein the one or more vertical diffusion barriers correspond to a liner material of a via formed above the metal line, with the via extending completely through a thickness of the metal line such that a bottom most portion of the via comprises a portion of the metal line.