Semiconductor Metal Contact Structure for Low-Resistance Copper Barriers
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Solution Overview
Problem
As semiconductor devices evolve to smaller feature sizes, the challenge lies in forming reliable and stable metal contacts with low resistance and preventing copper diffusion, which affects the reliability and performance of interconnect structures.
Innovation Solution
A method involving the formation of a silicide layer, a copper diffusion barrier layer, and a conformal protective layer using cobalt or nickel, along with a thermal treatment to create a low-resistance contact and prevent copper diffusion, employing techniques like physical vapor deposition and chemical vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used as the conductive material in interconnect structures, then electrical conductivity is improved, but copper diffusion into surrounding materials occurs causing reliability degradation
Solution Approach 1:
A cobalt layer is introduced as an intermediary between the copper conductive material and the surrounding dielectric or silicide layers. This cobalt layer acts as a diffusion barrier that prevents copper atoms from migrating into adjacent materials during thermal processing, while maintaining electrical conductivity through the copper-cobalt interface.
Solution Approach 2:
The interconnect structure employs a composite material system consisting of copper conductive material combined with cobalt barrier layers. This composite structure leverages the high conductivity of copper while utilizing cobalt's diffusion-blocking properties, creating a multi-functional material system that addresses both electrical performance and reliability concerns.
2Productivity
If feature sizes are reduced to increase device density, then productivity is improved, but manufacturing precision requirements increase due to smaller tolerances
Solution Approach 1:
The invention changes the material parameters by introducing cobalt layers with specific thicknesses (e.g., 1-10 nm) and controlled stoichiometry. These parameter changes enable the formation of reliable diffusion barriers at scaled dimensions, maintaining manufacturing feasibility even as feature sizes decrease to increase device density.
Solution Approach 2:
Cobalt barrier layers are formed preliminarily before copper deposition and subsequent thermal processing steps. This preliminary action establishes the diffusion barrier in advance, preventing copper migration during later manufacturing steps, which is critical for maintaining precision in scaled devices.
3Reliability
If thermal treatment is applied to form silicide layers and improve electrical contact, then electrical conductivity is improved, but copper diffusion into the silicide layer increases
Solution Approach 1:
The cobalt layer serves as a thermal-stable intermediary that remains intact during silicide formation thermal treatments. It prevents direct contact between copper and the silicide layer, blocking copper diffusion pathways even when high temperatures are applied to create low-resistance electrical contacts.
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
This approach results in effective electrical contacts with low resistance and improved thermal stability, reducing RC delay issues and ensuring reliable semiconductor device performance.
Implementation Method 1
employing techniques like physical vapor deposition and chemical vapor deposition
Implementation Method 2
employing techniques like physical vapor deposition and chemical vapor deposition
Implementation Method 3
A thermal treatment is performed to react the first metal layer with the second metal layer to form an amorphous layer there-between and to form a silicide layer between the first metal layer and the substrate
Data Source
AI summary
A semiconductor device and method of formation are provided. The semiconductor device comprises a silicide layer over a substrate, a metal plug in an opening defined by a dielectric layer over the substrate, a first metal layer between the metal plug and the dielectric layer and between the metal plug and the silicide layer, a second metal layer over the first metal layer, and an amorphous layer between the first metal layer and the second metal layer.