GaN Vertical Power Device Horizontal PN-Junction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current vertical GaN power devices face challenges in achieving low on-resistance and high withstanding voltage due to lattice constant differences, leading to warpage, defects, and high costs when using heterogeneous substrates, and low productivity with homogeneous substrates.
Innovation Solution
A semiconductor structure with a PN-junction structure formed in a direction perpendicular to the source and drain electrodes, utilizing a mask layer to limit semiconductor growth and including high-concentration doped regions, which reduces on-resistance while increasing withstanding voltage by forming a horizontal PN-junction surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the channel length is increased to increase withstanding voltage, then the withstanding voltage is improved, but the on-resistance becomes high
Solution Approach 1:
The patent introduces a horizontal PN-junction structure that extends in the lateral direction (second direction) rather than only vertically. This dimensional change allows the depletion region to expand horizontally to increase withstanding voltage, while maintaining a shorter vertical channel length to keep on-resistance low. The third semiconductor region extends horizontally from the first semiconductor region, creating a lateral breakdown path that supplements the vertical voltage blocking capability.
Solution Approach 2:
The patent employs a composite semiconductor structure with multiple regions of different conductivity types (n-type first semiconductor region, p-type second semiconductor region, n-type third semiconductor region) forming a PN-junction. This composite structure combines the voltage-blocking capability of the vertical drift region with the lateral breakdown characteristics of the horizontal PN-junction, achieving both high withstanding voltage and low on-resistance through material composition and structural integration.
2Strength
If GaN is grown to a thick thickness on a heterogeneous substrate to increase channel length, then the withstanding voltage is improved, but warpage, defects, and breakage occur due to lattice constant difference
Solution Approach 1:
Instead of increasing channel length solely by growing thicker GaN vertically (first direction), the patent extends the channel in the horizontal direction (second direction) through the lateral extension of the third semiconductor region. This dimensional change allows achieving the necessary channel length for high withstanding voltage without requiring excessive vertical thickness that would cause warpage and defects on heterogeneous substrates.
Solution Approach 2:
The patent divides the channel structure into multiple semiconductor regions (first, second, and third regions) with alternating conductivity types, forming a segmented PN-junction structure. This segmentation allows the channel to be distributed across different spatial locations and orientations, reducing the stress concentration and lattice mismatch issues that would arise from a single continuous thick GaN layer.
3Reliability
If a homogeneous GaN substrate is used to avoid warpage and defects, then reliability is improved, but costs are very high and wafer size is small, leading to low productivity
Solution Approach 1:
The patent applies local quality by creating regions with different doping concentrations and conductivity types within the GaN structure. The high-concentration doped regions are locally introduced to form the PN-junction, while the bulk GaN layer can be grown on cost-effective heterogeneous substrates. This localized modification allows achieving high reliability in critical regions without requiring expensive homogeneous substrates throughout the entire structure.
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
The solution effectively lowers on-resistance and enhances withstanding voltage performance in vertical power devices, addressing the limitations of existing technologies by utilizing a horizontal PN-junction structure and high-concentration doping.
Implementation Method 1
a first semiconductor region of a first conductivity type between the substrate and the at least one mask layer; a second semiconductor region of a second conductivity type on the at least one mask layer
Implementation Method 2
a third semiconductor region of the first conductivity type on the first semiconductor region, the third semiconductor region contacting the second semiconductor region to form a PN-junction structure in a second direction different from the first direction
Data Source
AI summary
A semiconductor structure includes a substrate; at least one mask layer spaced apart from the substrate in a first direction; a first semiconductor region of a first conductivity type between the substrate and the at least one mask layer; a second semiconductor region of a second conductivity type on the at least one mask layer; and a third semiconductor region of the first conductivity type on the first semiconductor region. The third semiconductor region may contact the second semiconductor region to form a PN-junction structure in a second direction different from the first direction. The semiconductor structure may be applied to vertical power devices and may be capable of increasing withstand voltage performance and lowering an on-resistance.