Cu-Mn Alloy Barrier Layer for Semiconductor Wiring
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Solution Overview
Problem
Conventional barrier layers in semiconductor devices fail to effectively prevent copper diffusion into insulating films, leading to increased resistance and reduced reliability due to inadequate adhesion and diffusion barriers.
Innovation Solution
A semiconductor device with a barrier layer made of Mn-based oxide, where the atomic concentration of manganese is maximized in the central part, and copper concentration decreases monotonically from the wiring to the insulating film, enhancing adhesion and barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional barrier layer of Ta or TaN is formed to suppress Cu diffusion, then the insulating film is protected from Cu diffusion, but the effective resistance of the wiring increases due to the high resistance of the barrier layer occupying a larger ratio of the wiring width
Solution Approach 1:
The invention changes the material composition parameters of the barrier layer by forming a Cu-rich alloy layer with specific composition (Cu: 70-95 at%, Mn: 5-30 at%) and controlling the atomic concentration distribution after heat treatment to achieve optimal resistance characteristics
Solution Approach 2:
The invention uses a composite structure consisting of a Cu-Mn alloy barrier layer integrated with the Cu wiring, where the barrier layer contains Cu-rich regions for low resistance and Mn-rich regions for diffusion prevention, combining the benefits of both conductive and barrier materials
2Productivity
If the width of the wiring is decreased to increase the degree of integration, then the integration density increases, but the ratio of the thickness of the barrier layer occupied in the wiring width increases, inevitably increasing the effective resistance of the wiring
Solution Approach 1:
The invention changes the barrier layer material from conventional high-resistance Ta/TaN to a Cu-Mn alloy with controlled composition and atomic distribution, achieving lower resistance that allows narrower wiring widths without excessive resistance penalty
Solution Approach 2:
The invention creates local quality variations within the barrier layer by controlling the atomic concentration distribution of Cu and Mn, with Cu-rich regions providing low resistance pathways and Mn-rich regions providing diffusion barriers, allowing the barrier layer to serve multiple functions simultaneously
3Strength
If a Cu alloy film is heated to self-matchingly form a barrier layer, then the adhesion with the insulating film is enhanced, but sufficient barrier property against Cu diffusion cannot be secured and Si diffusion increases wiring resistance
Solution Approach 1:
The invention precisely controls the composition parameters (Cu: 70-95 at%, Mn: 5-30 at%) and heat treatment conditions to achieve the optimal atomic concentration distribution, where Mn atoms form a dense sub-oxide layer that provides both adhesion and diffusion barrier properties simultaneously
Solution Approach 2:
The invention creates a replicated atomic structure at the interface by forming a barrier layer with the same Cu-Mn alloy composition as the underlying wiring, ensuring continuous atomic distribution and preventing abrupt interfaces that would facilitate diffusion while maintaining strong adhesion
4Manufacturing precision
If the barrier layer is made thinner to reduce its occupation ratio in the wiring width, then the effective resistance of the wiring decreases, but the barrier property against Cu diffusion becomes insufficient
Solution Approach 1:
The invention changes the barrier mechanism from relying on physical thickness to relying on controlled atomic concentration distribution, where the Cu-rich alloy layer with specific composition provides diffusion barrier properties through compositional gradient rather than thickness alone
Solution Approach 2:
The invention creates a composite Cu-Mn alloy barrier layer where Cu provides low resistance and Mn provides diffusion barrier functionality, allowing the barrier layer to be thin while maintaining both low resistance and effective diffusion prevention through the synergistic combination of materials
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 solution effectively suppresses copper and silicon diffusion, reducing resistance and improving the reliability of semiconductor devices by forming a thermally stable, compact barrier layer that maintains low electric power consumption.
Implementation Method 1
heating a film of Cu alloy, such as an alloy of Cu and manganese (Mn) (Cu—Mn-based alloy), deposited on an insulating film to self-matchingly form a barrier layer
Implementation Method 2
a sputtering target for use in the fabrication method
Data Source
AI summary
A semiconductor device enables a barrier layer to fully acquire a barriering property against the diffusion of Cu from a wiring main body and the diffusion of Si from an insulating film, enhances the adhesiveness of the barrier layer and the insulating film and excels in reliability of operation over a long period of time. In this invention, a semiconductor device 1 provided on an insulating film 3 with a wiring includes the insulating film 3 containing silicon (Si), a wiring main body 8 formed of copper (Cu) in a groove-like opening 4 disposed in the insulating film 3, and a barrier layer 7 formed between the wiring main body 8 and the insulating film 3 and made of an oxide containing Cu and Si and Mn in such a manner that the atomic concentration of Cu decreases monotonously from the wiring main body 8 side toward the insulating film 3 side, the atomic concentration of Si decreases monotonously from the insulating film 3 side toward the wiring main body 8 side, and the atomic concentration of Mn is maximized in the region in which the atomic concentration of Cu and the atomic concentration of Si are approximately equal.