GaN Switching Element Recessed Body Layer Defect Reduction
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Solution Overview
Problem
It is challenging to reduce crystal defects in p-type semiconductor layers formed on GaN semiconductor substrates through annealing, leading to increased on-resistance in switching elements, as the crystallinity of GaN substrates is difficult to recover post-ion implantation, resulting in higher on-resistance and potential losses in switching elements.
Innovation Solution
A method involving the formation of a recessed portion on a GaN semiconductor substrate, growth of a p-type GaN semiconductor layer within this recess, and subsequent exposure of n-type semiconductor layers, allowing for the formation of a gate electrode without ion implantation, thereby reducing crystal defects and on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ion implantation is used to form a p-type body layer in GaN semiconductor substrate, then the body layer can be formed, but crystal defects are formed and crystallinity cannot be recovered through annealing, leading to increased on-resistance
Solution Approach 1:
The patent extracts the harmful ion implantation process from the body layer formation method. Instead of implanting ions into the GaN substrate to create the p-type body layer, the invention uses a different approach (such as selective epitaxial growth or other defect-free formation methods) that achieves the same functional result without introducing crystal defects that cannot be annealed out.
Solution Approach 2:
The patent changes the fundamental parameter of body layer formation from ion implantation to an alternative method. This parameter change eliminates the creation of irreversible crystal defects in the GaN lattice, thereby maintaining lower on-resistance values while still achieving the necessary p-type conductivity in the body layer.
2Quantity of substance
If ion implantation is used to form p-type semiconductor layer, then doping can be achieved, but crystal defect density increases and cannot be reduced through annealing
Solution Approach 1:
The patent removes the ion implantation step from the doping process. Instead of forcing ions into the GaN lattice (which creates defects), the invention employs alternative doping methods such as in-situ doping during epitaxial growth or molecular beam epitaxy, which can achieve the desired doping concentration without creating irreversible crystal defects.
Solution Approach 2:
The patent replaces the mechanical ion implantation process with a chemical or vapor-phase deposition process. This substitution allows dopant atoms to be incorporated into the GaN lattice during crystal growth in a more gentle and controlled manner, achieving the required doping levels without the high-energy damage and crystal defect formation associated with ion implantation.
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 enables the manufacturing of switching elements with lower on-resistance and reduced variations in on-resistance and gate threshold values, improving the reliability and efficiency of the switching elements during mass production.
Implementation Method 1
growing a body layer which is a p-type GaN semiconductor layer within the recessed portion and on the surface of the GaN semiconductor substrate
Data Source
AI summary
A method of manufacturing a switching element includes forming a recessed portion in a surface of a GaN semiconductor substrate in which a first n-type semiconductor layer is exposed on the surface, growing a p-type body layer within the recessed portion and on the surface of the GaN semiconductor substrate, removing a surface layer portion of the body layer to expose the first n-type semiconductor layer on the surface of the GaN semiconductor substrate, and leave the body layer within the recessed portion, forming a second n-type semiconductor layer which is separated from the first n-type semiconductor layer by the body layer and is exposed on the surface of the GaN semiconductor substrate, and forming a gate electrode which faces the body layer through an insulating film.