Silicon Carbide Semiconductor Device Nickel Diffusion Barrier
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Solution Overview
Problem
Traditional silicon carbide semiconductor devices face challenges in preventing nickel diffusion into interlayer insulating films during the formation of nickel silicide contacts, leading to reduced dielectric strength and semiconductor reliability.
Innovation Solution
A method involving the formation of a titanium nitride film with a columnar crystal structure and grain size of 20 nm to 50 nm, which is heat-treated to increase grain size and reduce interstices, is used to cover the interlayer insulating film and prevent nickel intrusion during the formation of nickel silicide contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nickel film is formed on the silicon carbide substrate to create an ohmic contact, then the electrical contact performance is improved, but nickel diffuses into the interlayer insulating film causing reduced dielectric strength and reliability
Solution Approach 1:
A titanium nitride film is introduced as an intermediary barrier layer between the nickel film and the interlayer insulating film. The titanium nitride film has a columnar crystal structure with controlled grain size (20-50 nm) that acts as a diffusion barrier, preventing nickel atoms from migrating into the insulating film while allowing the nickel film to maintain its ohmic contact function with the silicon carbide substrate.
Solution Approach 2:
The grain size of the titanium nitride film is precisely controlled within the range of 20-50 nm through specific deposition conditions. This parameter optimization creates a columnar crystal structure with reduced interstices, which effectively blocks nickel diffusion pathways while maintaining the barrier film's structural integrity and electrical properties.
2Strength
If a titanium nitride film is formed to prevent nickel diffusion, then the dielectric strength is maintained, but the film may exhibit peeling and cracking due to stress
Solution Approach 1:
The grain size of the titanium nitride film is optimized to 20-50 nm, creating a columnar crystal structure that reduces internal stress and prevents peeling and cracking. This specific grain size range maintains the film's structural stability while preserving its function as a nickel diffusion barrier.
Solution Approach 2:
The titanium nitride film exhibits different structural characteristics at different locations: columnar grains are oriented vertically with their growth direction perpendicular to the substrate surface. This local structural arrangement reduces stress concentration and prevents film degradation while maintaining effective nickel diffusion blocking at the grain boundaries.
3Object-generated harmful factors
If the titanium nitride film has small grain size to prevent nickel diffusion, then the barrier effectiveness is improved, but the film becomes more susceptible to peeling and cracking
Solution Approach 1:
The grain size is optimized to a specific range of 20-50 nm, which is small enough to provide effective nickel diffusion barriers through reduced interstices but large enough to maintain sufficient mechanical strength and prevent film peeling and cracking. This parameter optimization balances diffusion blocking effectiveness with structural integrity.
Solution Approach 2:
The titanium nitride film forms a composite structure with columnar grains arranged vertically, creating a unique microarchitecture that combines the benefits of fine-grained diffusion barriers with the mechanical strength of a cohesive film structure. The columnar arrangement provides both diffusion blocking pathways and stress distribution characteristics.
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 suppresses nickel penetration into the interlayer insulating film, maintaining dielectric strength and improving semiconductor reliability by ensuring a stable ohmic contact and reducing the likelihood of peeling and cracking in the titanium nitride film.
Implementation Method 1
the titanium nitride film is heat-treated so as to increase a grain size of the titanium nitride film
Implementation Method 2
heat treatment whereby at the contact hole, a nickel silicide film forming an ohmic contact is formed on the front surface of the silicon carbide substrate
Implementation Method 3
The silicon carbide substrate and the nickel film are caused to react by heat treatment whereby at the contact hole, a nickel silicide film forming an ohmic contact is formed
Data Source
AI summary
After a titanium nitride film is formed to cover an interlayer insulating film, a first nickel film is formed on a front surface of a silicon carbide base exposed in a contact hole, so as to extend on the titanium nitride film. Next, the silicon carbide base and the first nickel film are reacted by rapid thermal annealing at a temperature of 800 to 1100 degrees C. to form a nickel silicide film that forms an ohmic contact. Grains of the titanium nitride film are enlarged by the rapid thermal annealing, making a grain size of the titanium nitride film 20 nm to 50 nm. Thus, interstices of the grains of the titanium nitride film become smaller than before the rapid thermal annealing or are eliminated, enabling the intrusion of nickel from the first nickel film into the interstices of the columnar grains of the titanium nitride film to be suppressed.