Ruthenium-on-Cobalt Deposition to Prevent Co-Ru Interface Resistance
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Solution Overview
Problem
The direct stacking of a ruthenium film on a cobalt film in semiconductor manufacturing leads to interfacial diffusion and increased electrical resistance due to the formation of a Co-Ru alloy during high-temperature annealing, which is exacerbated by the formation of an oxide layer when boron-containing gases are used.
Innovation Solution
A method involving the alternately repeated deposition of ruthenium thin films and boron compound gases to form a ruthenium film with boron, preventing interfacial diffusion and oxide layer formation by controlling the thickness and structure of the ruthenium film, thereby maintaining low electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ruthenium film is directly formed on a cobalt film, then the ruthenium film can be deposited, but interfacial diffusion occurs during high-temperature annealing forming a Co-Ru alloy that increases electrical resistance
Solution Approach 1:
A boron-containing intermediate layer is introduced between the ruthenium film and cobalt film to prevent direct interfacial diffusion. The boron layer acts as a diffusion barrier that stops Co and Ru atoms from mixing during high-temperature annealing, thereby preventing alloy formation and maintaining low electrical resistance at the interface.
Solution Approach 2:
The boron-containing layer is formed on the cobalt film surface before ruthenium deposition. This preliminary action creates a protective barrier in advance that prevents interfacial diffusion during subsequent annealing processes, avoiding the need for post-processing corrections.
2Strength
If boron-containing gas is supplied to increase adhesion, then adhesion between Ru film and SiCOH film improves, but oxide layer formation increases electrical resistance
Solution Approach 1:
The boron-containing gas is supplied in a nitrogen atmosphere that prevents oxidation. The nitrogen environment acts as an inert barrier that stops oxygen from reacting with boron to form oxide layers, while still allowing the boron to diffuse into the ruthenium film to improve adhesion.
Solution Approach 2:
The oxidation state of the boron-containing layer is controlled by adjusting process parameters such as gas composition, temperature, and pressure. By optimizing these parameters, the boron layer provides adhesion enhancement without forming resistive oxide layers.
3Reliability
If multiple deposition cycles are performed, then film quality and diffusion prevention improve, but manufacturing time increases
Solution Approach 1:
Instead of performing multiple complete deposition cycles, the patent uses a single or reduced number of cycles with optimized boron-containing gas supply timing. The boron gas is supplied at critical moments during deposition to achieve sufficient adhesion and diffusion prevention without requiring excessive processing time.
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 effectively prevents the formation of a Co-Ru alloy and oxide layers, maintaining low electrical resistance and ensuring the integrity of the ruthenium film on the cobalt film, even under annealing conditions.
Implementation Method 1
forming a ruthenium thin film by supplying a ruthenium raw material gas to the substrate on which the conductive film is formed
Implementation Method 2
the conductive film includes a metal that increases an electrical resistance between the conductive film and the ruthenium film by interfacial diffusion between the conductive film and the ruthenium film
Data Source
AI summary
A method for manufacturing a semiconductor device that includes forming a ruthenium film on a conductive film formed on a substrate for manufacture of the semiconductor device, wherein the conductive film includes a metal that increases an electrical resistance between the conductive film and the ruthenium film by interfacial diffusion between the conductive film and the ruthenium film, and wherein the method comprises forming the ruthenium film on the conductive film by alternately repeating a plurality of times: forming a ruthenium thin film by supplying a ruthenium raw material gas to the substrate on which the conductive film is formed; and then supplying a boron compound gas to the ruthenium thin film.