Silicon Carbide Doping Layout to Suppress Annealing Diffusion
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Solution Overview
Problem
The challenge in manufacturing semiconductor devices using silicon carbide is the diffusion of impurities during heat treatment, which hinders the scaling-down of devices and degrades the performance of components like PiN Schottky diodes and MOSFETs due to carbon vacancies in the silicon carbide layer.
Innovation Solution
A method involving ion implantation of carbon to create a carbon region wider than the impurity implantation range, followed by heat treatment, which reduces carbon vacancies and suppresses impurity diffusion, thereby maintaining device performance and enabling device scaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed to activate impurities in silicon carbide, then impurity activation is improved, but impurity diffusion occurs due to carbon vacancies
Solution Approach 1:
Carbon ions are implanted into the silicon carbide substrate before the heat treatment process. This preliminary carbon implantation ensures that carbon is present in the lattice structure prior to heating, preventing carbon vacancies from forming during the heat treatment that would otherwise cause impurity diffusion. The carbon implantation dose and energy are carefully controlled to achieve the desired carbon concentration without creating excessive defects.
Solution Approach 2:
The patent modifies the carbon concentration parameter in the silicon carbide substrate by implanting carbon ions at specific doses and energies. This parameter change addresses the root cause of impurity diffusion (carbon vacancies) while enabling the heat treatment to proceed effectively for impurity activation. The carbon implantation parameters are optimized to balance vacancy suppression with minimal disruption to the substrate structure.
2Productivity
If device scaling is pursued to improve integration density, then productivity is improved, but impurity diffusion degrades device performance
Solution Approach 1:
Carbon implantation is performed as a preliminary step before device fabrication and heat treatment processes. This ensures that the silicon carbide substrate is pre-conditioned with adequate carbon concentration to prevent impurity diffusion during subsequent processing, enabling tighter device spacing without performance degradation from diffusion.
Solution Approach 2:
By controlling the carbon implantation parameters (dose, energy, temperature), the patent creates a carbon-enriched region that suppresses impurity diffusion. This parameter modification enables smaller device dimensions and closer spacing while maintaining precise impurity profiles, thus achieving higher integration density without sacrificing manufacturing precision.
3Manufacturing precision
If carbon implantation is performed to suppress impurity diffusion, then impurity diffusion is reduced, but device complexity increases
Solution Approach 1:
The patent extracts the carbon implantation step as a separate, standalone process that can be performed independently of the main device fabrication sequence. This modular approach allows the carbon implantation to be integrated into existing production lines without fundamentally redesigning the overall manufacturing process, thus limiting the increase in device complexity.
Solution Approach 2:
The carbon implantation process uses standard ion implantation parameters that can be controlled with existing equipment. By optimizing the implantation dose and energy to achieve effective carbon concentration with minimal processing steps, the patent suppresses impurity diffusion while keeping the added process complexity manageable.
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 reduces impurity diffusion, improves the on-resistance of semiconductor devices, and enhances the reliability of components by maintaining high crystallinity and reducing the on-resistance of PiN Schottky diodes and MOSFETs.
Implementation Method 1
performing first ion implantation of forming a first carbon region by implanting carbon (C) into the silicon carbide layer
Implementation Method 2
performing heat treatment at 1600° C. or higher
Implementation Method 3
activation annealing of impurities
Data Source
AI summary
A method for manufacturing a semiconductor device according to an embodiment includes forming a first mask material having a first opening on a surface of a silicon carbide layer, performing first ion implantation of forming a first carbon region by implanting carbon (C) into the silicon carbide layer using the first mask material as a mask, forming, on the surface of the silicon carbide layer, a second mask material in which both end portions in a first direction parallel to the surface have second openings disposed inside both end portions in the first direction of the first carbon region, performing second ion implantation of forming a first impurity region by implanting a first impurity into the silicon carbide layer using the second mask material as a mask, and performing heat treatment at 1600° C. or higher.