Copper Wiring Formation via PVD and Annealing
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Solution Overview
Problem
Current methods for forming copper wiring in fine trenches or holes face challenges such as void formation, incomplete filling, and high impurity levels, especially with the miniaturization of semiconductor devices, and require additional equipment and processes like copper plating, which increases complexity and costs.
Innovation Solution
A method using Physical Vapor Deposition (PVD) to form copper wiring by creating a barrier film and a ruthenium film, followed by copper film deposition while annealing the substrate, ensuring copper migration into the trench or hole without voids, and employing a two-stage film-forming process with controlled bias power and temperature to achieve complete embedding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma sputtering is used to form barrier film and seed film in fine trenches or holes, then the films can be formed on the substrate, but overhang is generated in the opening of the trench or hole, resulting in incomplete filling and void formation during subsequent Cu plating
Solution Approach 1:
The patent extracts the plating process from the overall Cu wiring formation process, achieving complete filling of fine trenches and holes using PVD alone. By removing the plating step, the method eliminates overhang formation and void issues while simplifying the process flow.
Solution Approach 2:
The patent changes the deposition parameters by using a dual-frequency RF sputtering system with specific power ratios (e.g., 13.56 MHz and 27.12 MHz frequencies). By controlling the ionization rate and deposition rate through parameter adjustment, complete filling is achieved without overhang, eliminating the need for plating.
2Manufacturing precision
If Cu plating is used to embed Cu in fine trenches or holes, then embedment can be improved, but a plating apparatus is required in addition to PVD apparatus, increasing equipment costs and process complexity
Solution Approach 1:
The patent merges the barrier film formation, seed film formation, and Cu filling processes into a single PVD system. By combining multiple functions into one apparatus, the method eliminates the need for separate plating equipment while maintaining high embedment quality in fine trenches and holes.
Solution Approach 2:
The PVD apparatus is designed with multi-functionality to perform barrier film deposition, seed film deposition, and Cu filling in a single system. This universal approach replaces the need for dedicated plating equipment, reducing equipment costs and process complexity.
3Manufacturing precision
If Cu plating is used to form Cu wiring, then the trench or hole can be filled, but a large quantity of impurities is introduced, preventing sufficient reduction of wiring resistance
Solution Approach 1:
The patent replaces the chemical plating process with a physical vapor deposition process. By substituting chemical reactions with physical sputtering and thermal migration, the method achieves complete filling without introducing plating impurities, thereby reducing wiring resistance.
Solution Approach 2:
The patent changes the deposition mechanism from chemical plating to PVD with thermal migration. By controlling temperature and sputtering parameters, pure Cu is deposited and migrated into the trench or hole, achieving complete filling without impurity contamination.
4Device complexity
If only PVD is used to form Cu wiring in narrow trenches or holes, then equipment costs and process complexity are reduced, but it has not been realized that Cu can be completely embedded without voids
Solution Approach 1:
The patent achieves complete embedment using only PVD by optimizing deposition parameters including dual-frequency RF power ratios, pressure control, and temperature management. These parameter changes enable thermal migration of Cu atoms to completely fill narrow trenches and holes without void formation.
Solution Approach 2:
The patent performs preliminary actions by forming a Ru film on the barrier film before Cu deposition. This preliminary Ru layer facilitates Cu migration and ensures complete filling during the subsequent PVD process, achieving void-free embedment in fine features.
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 allows for the formation of copper wiring with lower resistance and reduced impurities, completely filling fine trenches or holes without voids, and eliminates the need for copper plating, simplifying the process and reducing equipment costs.
Implementation Method 1
forming a barrier film on the surface of the concave portion
Implementation Method 2
forming a Ru film on the barrier film
Implementation Method 3
embedding Cu in the concave portion by forming a Cu film on the Ru film using PVD
Implementation Method 4
while annealing the substrate such that migration of Cu into the concave portion occurs
Implementation Method 5
migration of Cu into the concave portion occurs
Data Source
AI summary
A method of forming a Cu wiring in a trench or hole formed in a substrate is provided. The method includes forming a barrier film on the surface of the trench or hole, forming a Ru film on the barrier film, and embedding Cu in the trench or hole by forming a Cu film on the Ru film using PVD while annealing the substrate such that migration of copper into the trench or hole occurs.