Graphene-Copper Interconnect Structure for Low-Leakage Semiconductor Wiring
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Solution Overview
Problem
Conventional semiconductor devices face issues of leakage current and increased resistance due to the miniaturization of semiconductor devices, primarily caused by the use of copper and aluminum, which have high diffusion coefficients and require denser barrier layers like tantalum nitride and titanium nitride, leading to increased resistance.
Innovation Solution
The use of a graphene-copper composite material with graphene flakes dispersed between copper atoms, forming covalent bonds, as the lower wiring layers in the semiconductor device, which suppresses copper diffusion and replaces the need for barrier layers, thereby reducing resistance and leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper and aluminum are used as metal materials in the back-end of line process, then good conductivity is achieved, but diffusion coefficients are large causing leakage current problems
Solution Approach 1:
The patent uses a graphene-copper composite material where graphene flakes are dispersed in the copper matrix. The graphene forms a barrier network that suppresses copper diffusion into dielectric layers while maintaining the high electrical conductivity of copper. This composite structure resolves the contradiction by combining the conductivity benefit of copper with the diffusion barrier property of graphene.
2Object-generated harmful factors
If denser barrier layers like tantalum nitride and titanium nitride are used to prevent short circuits, then leakage current is reduced, but resistance increases
Solution Approach 1:
The patent extracts and eliminates the traditional TaN and TiN barrier layers from the interconnect structure. Instead of adding barrier layers, it uses the graphene-copper composite material where graphene inherently provides diffusion barrier functionality. This removal of separate barrier layers directly reduces the overall resistance while maintaining leakage current protection.
3Productivity
If semiconductor device lines are miniaturized to follow Moore's Law, then integration density increases, but RC delay has significant impact on operating speed
Solution Approach 1:
The graphene-copper composite material provides both high electrical conductivity (reducing RC delay) and structural stability at miniaturized dimensions. The graphene reinforcement in the copper matrix maintains wiring integrity and reduces resistance even as line dimensions decrease, thereby preserving operating speed despite increased integration density.
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 graphene-copper composite material effectively suppresses copper diffusion, reduces resistance, and enhances stability, making the semiconductor device more stable and suitable for advanced processes like the 2 nm node, with low resistance and high thermal conductivity.
Implementation Method 1
graphene flakes dispersed between copper atoms, forming covalent bonds
Implementation Method 2
suppresses copper diffusion
Implementation Method 3
low resistance and high thermal conductivity
Implementation Method 4
high thermal conductivity
Data Source
AI summary
A semiconductor device includes a substrate, an ILD layer on the substrate, a contact electrode unit with a gate wiring layer and contacts in the ILD layer, a lower IMD layer on the ILD layer, a wiring unit with lower and upper wiring layers disposed on the lower IMD layer and connected to the contacts, interconnect units stacked along a height direction on the wiring unit, including an upper IMD layer, lower and upper wiring layers and interconnects in the upper IMD layer and connected to each other; and a bonding pad unit including an insulating layer, interconnects and an upper wiring layer in the insulating layer connected to each other. The lower wiring layer is made of a graphene-copper composite material having graphene flakes covalently bonded and dispersed between copper atoms. The graphene content is less than 3 wt % and the oxygen content is no more than 10 ppm.