Cobalt-Tungsten Isolation Layer for Copper Diffusion Control
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Solution Overview
Problem
The existing methods for manufacturing semiconductor structures using metal wires, particularly with copper, face challenges in preventing copper atom diffusion to the substrate, leading to parasitic capacitance and reduced service life, as tantalum isolation layers are ineffective.
Innovation Solution
A method involving a physical vapor deposition process to create an isolation layer with cobalt atoms and tungsten barrier atoms at grain boundaries, which effectively prevents copper atom diffusion and enhances adhesion with the copper-containing metal layer, improving electron mobility and service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tantalum isolation layer is used to prevent copper atom diffusion, then the structure provides isolation between copper layer and substrate, but the isolation effect is poor and copper atoms still diffuse to substrate generating parasitic capacitance
Solution Approach 1:
The patent changes the material composition parameters of the isolation layer by incorporating cobalt atoms with specific concentration (5-20 at%) and controlling the grain boundary characteristics. This parameter modification transforms the isolation layer from ineffective tantalum to an effective cobalt-based barrier that prevents copper atom diffusion while maintaining low parasitic capacitance.
Solution Approach 2:
The patent creates a composite isolation layer structure combining cobalt atoms forming the matrix with barrier atoms concentrated at grain boundaries. This composite approach leverages the high resistance of cobalt to copper diffusion and the grain boundary barrier effect, achieving superior isolation performance compared to pure tantalum layers.
2Productivity
If the width of metal wires is reduced to improve integration, then the grain size of copper becomes smaller, but copper atoms become easier to diffuse to substrate
Solution Approach 1:
The patent applies local quality enhancement by concentrating barrier atoms specifically at the grain boundaries of the cobalt structure. This localized barrier placement is particularly effective for fine-pitch interconnects with small grain sizes, as it creates multiple localized barriers that prevent copper diffusion paths even when overall grain dimensions are reduced for higher integration.
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 reduces parasitic capacitance and extends the service life of semiconductor structures by preventing copper atom diffusion and improving the structural performance through high adhesion and low resistivity of the cobalt-tungsten alloy isolation layer.
Implementation Method 1
depositing an isolation layer on the insulating substrate by a physical vapor deposition process
Implementation Method 2
barrier atoms located at grain boundaries of the cobalt atoms; the diffusion of copper atoms from the grain boundaries of the cobalt to the insulating substrate can be prevented
Data Source
AI summary
An embodiment of the present application relates to the technical field of semiconductors, and discloses a method for manufacturing a semiconductor structure. In this embodiment, the method comprises: providing an insulating substrate (101); depositing an isolation layer (103) on the insulating substrate (101) by a physical vapor deposition process, the isolation layer (103) comprising cobalt atoms and barrier atoms located at grain boundaries of the cobalt atoms; and depositing a copper-containing metal layer (104) on the isolation layer (103).