Aluminum Interconnect Structure With Migration Barrier Against Voiding
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Solution Overview
Problem
Aluminum structures in semiconductor devices are prone to voiding due to vacancy diffusion, especially under thermal cycling, which increases the risk of yield degradation and reliability issues such as electro migration (EM) and stress migration (SM), particularly in narrow structures where stress gradients are higher.
Innovation Solution
Incorporating an inert aluminum oxide, aluminum nitride, or aluminum oxynitride layer as a migration barrier between aluminum layers, formed by interrupting the aluminum deposition process with vacuum exposure and plasma treatment, to block vacancy diffusion and reduce voiding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum layers are deposited without interruption to maintain process simplicity, then manufacturing ease is improved, but vacancy diffusion occurs leading to voiding and reduced reliability
Solution Approach 1:
The continuous aluminum deposition process is segmented into interrupted stages with vacuum exposure in between. This segmentation allows the formation of a migration barrier layer without adding separate deposition steps, resolving the contradiction by using process interruption rather than structural addition.
Solution Approach 2:
Vacuum exposure acts as an intermediary mechanism that transforms the aluminum surface in-situ during deposition. This creates a migration barrier layer that prevents vacancy diffusion without requiring additional material layers or complex process equipment.
2Reliability
If aluminum deposition is interrupted with vacuum exposure to form migration barrier, then voiding is reduced, but manufacturing complexity increases
Solution Approach 1:
The aluminum layer itself serves the dual function of being both the conductive material and the source of the migration barrier. Vacuum exposure triggers self-transformation of the aluminum surface without requiring external materials or complex additional steps, making the process self-serving and easier to manufacture.
Solution Approach 2:
The deposition process parameters are dynamically changed by introducing vacuum exposure intervals. This parameter change transforms the aluminum surface properties in-situ to create a migration barrier, achieving improved reliability through parameter modulation rather than process complexity.
3Length of moving object
If narrow aluminum structures are used to reduce device size, then device miniaturization is improved, but stress gradients increase leading to higher voiding risk
Solution Approach 1:
The migration barrier property is applied locally at the aluminum surface where vacancy diffusion occurs. This local quality enhancement provides targeted protection against stress migration in narrow structures without requiring overall structural changes, maintaining miniaturization while improving reliability.
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 introduction of a migration barrier layer reduces electro migration and stress migration, enhancing the thermal stability and reliability of semiconductor devices by minimizing void formation and improving performance.
Implementation Method 1
Aluminum structures are prone to voiding due to vacancy diffusion
Implementation Method 2
formed by interrupting the aluminum deposition process with vacuum exposure and plasma treatment
Data Source
AI summary
Devices with aluminum structures and methods of fabrication are provided. An exemplary device includes an interconnect structure and an aluminum structure electrically connected to the interconnect structure. The aluminum structure includes a first aluminum layer, a migration barrier layer over the first aluminum layer, and a second aluminum layer over the migration barrier layer.