Manganese Oxide Barrier Films for Copper Wiring Diffusion Control
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Solution Overview
Problem
In ultrafine and ultrahigh-speed semiconductor devices, the use of high-dielectric-constant barrier metal films leads to increased resistance and potential short circuits due to weak adhesion of manganese-silicon oxide diffusion barriers, and low-dielectric-constant porous films are prone to damage and oxidation during manufacturing, affecting the integrity of the barrier metal film and Cu wiring layer adhesion.
Innovation Solution
A semiconductor device with a multilayer wiring structure that includes a first insulating film, a first opening with a manganese oxide film on its inner wall, a copper wiring pattern, and a second manganese oxide film containing carbon, which enhances the diffusion barrier properties and adhesion to the Cu wiring layer by forming manganese oxide films with specific compositions and structures to prevent Cu atom diffusion and oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-dielectric-constant barrier metal film is used to prevent Cu diffusion, then diffusion barrier properties are improved, but adhesion to Cu wiring layer deteriorates and resistance increases
Solution Approach 1:
The barrier metal film is segmented into multiple layers with different functions: a lower barrier metal film (Ta/Ti/W) providing diffusion barrier properties, and an upper Cu-Mn alloy film providing adhesion to Cu wiring. This segmentation allows each layer to optimize its specific function without compromising the other.
Solution Approach 2:
The barrier metal structure uses composite materials by combining a high-melting-point metal (Ta/Ti/W) with a Cu-Mn alloy. The Cu-Mn alloy layer serves dual purposes: maintaining electrical conductivity and providing strong adhesion to the Cu wiring layer, while the underlying barrier metal film prevents Cu diffusion.
2Strength
If a Cu-Mn alloy layer is used as diffusion barrier, then adhesion to Cu wiring is improved, but the formed manganese-silicon oxide layer has weak adhesion and causes short circuits
Solution Approach 1:
The Cu-Mn alloy layer acts as an intermediary between the Cu wiring and the underlying barrier metal film. It forms a manganese-silicon oxide diffusion barrier that, while having lower adhesion, is compensated by the strong adhesion of the Cu-Mn alloy to the Cu wiring layer, creating a multi-functional interface structure.
3Speed
If low-dielectric-constant porous films are used to reduce signal delay, then RC delay is reduced, but the films are damaged by plasma and oxidized during manufacturing
Solution Approach 1:
The Cu-Mn alloy layer is deposited on the low-dielectric-constant porous film before plasma processing and oxidation steps. This preliminary action creates a protective interface that prevents direct interaction between the porous film and harsh manufacturing conditions, preserving film integrity while maintaining the low-k properties for reduced RC delay.
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 manganese oxide films with carbon compositions effectively prevent Cu atom diffusion, reducing short circuits and improving the adhesion and durability of the barrier metal film, thereby enhancing the performance and reliability of the semiconductor device.
Implementation Method 1
Mn atoms contained in a Cu—Mn alloy layer react with Si and oxygen atoms contained in an interlayer insulating film and thus a manganese-silicon oxide layer having a thickness in the range of 2 nm to 3 nm and a composition of MnSixOy is formed inside the Cu—Mn alloy layer as a diffusion barrier film
Implementation Method 2
a second manganese oxide film formed on the first copper wiring containing carbon
Data Source
AI summary
A semiconductor device has a first insulating film formed over a semiconductor substrate, a first opening formed in the first insulating film, a first manganese oxide film formed along an inner wall of the first opening, a first copper wiring embedded in the first opening, and a second manganese oxide film formed on the first copper wiring including carbon.