Cu-X Alloy Wiring with Aluminum Oxide Barrier for Semiconductor Reliability
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Solution Overview
Problem
In display devices using transistors, the variation in voltage applied due to wiring resistance leads to issues like display unevenness and grayscale defects, particularly with copper (Cu) wiring materials, where diffusion into semiconductor layers causes transistor deterioration and high contact resistance.
Innovation Solution
A semiconductor device with Cu—X alloy films (X = Mn, Ni, Cr, Fe, Co, Mo, Ta, or Ti) is used for wiring, where the alloy films are structured with specific inclination angles and connected through manganese oxide-containing insulating films to prevent Cu diffusion and reduce contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier layer of titanium nitride, tungsten nitride, or tantalum nitride is provided on the Cu wiring to prevent Cu diffusion, then Cu diffusion into the semiconductor layer is prevented, but contact resistance between wirings increases and wiring delay is caused
Solution Approach 1:
An aluminum oxide layer is introduced as an intermediary barrier between the Cu wiring and the oxide semiconductor layer. This aluminum oxide layer serves as the primary diffusion barrier, allowing the use of low-resistance Cu wiring while preventing Cu diffusion into the semiconductor. The intermediary barrier approach resolves the contradiction by decoupling the diffusion prevention function from the wiring material selection.
Solution Approach 2:
The wiring structure employs a composite material system consisting of Cu wiring combined with an aluminum oxide barrier layer. This composite structure leverages the low resistance of Cu while the aluminum oxide component provides effective diffusion prevention, achieving both low contact resistance and reliable Cu diffusion blocking.
2Manufacturing precision
If Cu film is used as wiring material to reduce resistance, then wiring resistance is reduced, but adhesion to base film is low and Cu diffusion into semiconductor layer causes transistor deterioration
Solution Approach 1:
The aluminum oxide layer acts as a mediator between the Cu wiring and the oxide semiconductor layer, enabling the use of low-resistance Cu wiring while preventing harmful Cu diffusion into the transistor. This intermediary barrier preserves the electrical performance benefits of Cu wiring while protecting transistor reliability.
Solution Approach 2:
The aluminum oxide barrier layer is formed in advance before any Cu diffusion can occur into the oxide semiconductor layer. This preliminary protective action prevents transistor deterioration by blocking Cu diffusion pathways before they can form, allowing Cu wiring to be used without compromising device reliability.
Data Source
AI summary
To provide a novel semiconductor device which includes a transistor and a metal film containing Cu for a wiring, a signal line, or the like. The semiconductor device includes a first wiring, a second wiring, a first transistor, and a second transistor. The first wiring is electrically connected to a source or a drain of the first transistor, and the second wiring is electrically connected to a gate of the second transistor. The first wiring and the second wiring each include a Cu—X alloy film (X is Mn, Ni, Cr, Fe, Co, Mo, Ta, or Ti). The Cu—X alloy film in the first wiring is connected to the Cu—X alloy film in the second wiring.