SiC Substrate with La Ce Ti for N Doping
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Solution Overview
Problem
Existing methods for producing N-doped SiC crystals face challenges in achieving high N donor concentration, particularly in specific regions, without damaging the crystal structure, and require excessive N2 gas or ion implantation, which can lead to structural defects.
Innovation Solution
A method involving the use of an SiC substrate with deposited or ion-implanted La, Ce, or Ti, allowing for efficient N doping by enhancing chemical reactivity and controlling N donor concentration through vapor-phase growth, annealing, and selective deposition or implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ion implantation method is used to increase N donor concentration in partial region, then N doping efficiency is improved, but crystal structure is damaged
Solution Approach 1:
The patent uses an SiO2 film as an intermediary layer between the ion implantation source and the SiC crystal. This film acts as a protective barrier that allows N ions to be implanted into the SiC crystal while preventing direct damage to the crystal structure. The SiO2 film can be removed after implantation, leaving the N-doped SiC crystal with intact structure and improved electrical properties.
Solution Approach 2:
The patent applies preliminary protective coating with SiO2 film before ion implantation. This preliminary action protects the SiC crystal surface from direct ion bombardment damage while still allowing ion penetration to achieve doping. The protective layer is prepared in advance and removed after the doping process completes.
2Productivity
If excessive N2 gas is supplied to increase N donor concentration, then N doping efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The patent changes the approach from controlling N doping through gas concentration parameters to using ion implantation parameters (ion energy, ion dose, implantation time). This parameter change allows precise control of N donor concentration without needing to supply excessive N2 gas, simplifying the manufacturing process while maintaining high doping efficiency.
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 method effectively increases N donor concentration in SiC crystals without damaging the structure, achieving higher N doping efficiency with reduced N2 gas usage and minimizing structural defects, enabling improved device performance.
Implementation Method 1
A method involving the use of an SiC substrate with deposited or ion-implanted La, Ce, or Ti, allowing for efficient N doping by enhancing chemical reactivity and controlling N donor concentration through vapor-phase growth
Implementation Method 2
supplying a raw material gas containing Si, C and N to vapor-grow an N-doped SiC crystal on an SiC substrate by a CVD method
Implementation Method 3
a heat treatment for recovering the crystal structure is generally performed
Data Source
Figure 1
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Figure 3(a)~3(e)
AI summary
A method for producing an SiC crystal, comprising supplying a raw material gas containing Si, C and N to vapor-grow an N-doped SiC crystal on an SiC substrate, wherein the SiC substrate is an SiC substrate on which La, Ce or Ti is deposited in part or whole of the surface or an SiC substrate in which La, Ce or Ti ion is implanted into part or whole of the surface.