Protective Wiring Layers for Electromigration-Resistant Semiconductors
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Solution Overview
Problem
As semiconductor devices become smaller and more integrated, the reduced size of transistors and their connecting wirings leads to issues such as void formation, surface metal migration, electromigration, and stress migration, which can break the conductive layers due to low activation energy and mechanical strength.
Innovation Solution
Incorporating a protective layer with a metal material having higher activation energy and mechanical strength than the conductive layer, covering the upper and side surfaces of the wiring, along with an interfacial alloy layer to enhance the interface strength, thereby reducing breakage and migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of transistors and wirings is reduced to increase integration, then device integration is improved, but the wiring becomes more susceptible to breakage and migration due to low activation energy and mechanical strength
Solution Approach 1:
The patent applies composite materials by creating a multi-layer wiring structure consisting of a conductive layer (first material) and a protective layer (second material) with different properties. The conductive layer provides electrical conductivity, while the protective layer with higher activation energy and mechanical strength prevents breakage and migration. This composite structure resolves the contradiction by maintaining small wiring dimensions for high integration while ensuring reliability through the protective layer's superior mechanical and thermal properties.
Solution Approach 2:
The patent applies local quality by providing different materials with different properties at different locations within the wiring structure. The protective layer is specifically positioned on the upper surface and side surfaces of the conductive layer where stress and migration are most problematic. This localized protection allows the wiring to maintain small dimensions for high integration while having enhanced reliability at critical locations susceptible to breakage and migration.
2Reliability
If a protective layer with higher activation energy and mechanical strength is added to prevent breakage and migration, then wiring reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the wiring into functionally distinct layers: a conductive layer for electrical conduction and a protective layer for mechanical strength and migration prevention. This segmentation allows each layer to be optimized for its specific function, improving reliability while keeping the overall structure manageable. The clear functional division makes the complex multi-layer structure easier to manufacture and analyze compared to a monolithic wiring design.
Solution Approach 2:
The protective layer serves multiple functions simultaneously: it provides mechanical strength to prevent breakage, supplies hydrogen to suppress void formation, and prevents surface metal migration. This multi-functionality reduces device complexity by consolidating multiple protective mechanisms into a single layer, eliminating the need for separate components for each function.
3Length of moving object
If the conductive layer is made thinner to reduce wiring size, then device miniaturization is improved, but the conductive layer becomes more prone to void formation and breakage
Solution Approach 1:
The patent applies the intermediary principle by introducing a protective layer as a mediator between the thin conductive layer and the external environment. This protective layer acts as a shield that prevents void formation and breakage in the thin conductive layer by providing mechanical support and supplying hydrogen to stabilize the interface. This allows the conductive layer to maintain its thin dimensions for device miniaturization while the protective layer compensates for the reduced strength.
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 protective layer and interfacial alloy layer strengthen the wiring, preventing breakage and migration, enhancing the reliability and longevity of the semiconductor device.
Implementation Method 1
an oxide layer covering the wiring pattern and formed on the insulating layer, wherein the oxide layer includes hydrogen
Implementation Method 2
the protective layer includes a metal material having an activation energy that is higher than that of a metal material of the conductive layer
Data Source
AI summary
A semiconductor device includes: a lower structure including a device and a lower wiring structure; an insulating layer on the lower structure; a via penetrating the insulating layer; a wiring pattern on the insulating layer and the via; and a silicon oxide layer covering the wiring pattern, and including hydrogen, wherein the wiring pattern includes first and second conductive layers, an upper surface protective layer, and a side surface protective layer, wherein the second conductive layer is on the first conductive layer, wherein the upper surface protective layer covers an upper surface of the second conductive layer, and the side surface protective layer covers side surfaces of the first and second conductive layers, and wherein each of the upper surface protective layer and the side surface protective layer includes a metal material having an activation energy higher than that of a metal material of the second conductive layer.