GaN Drain Contact Layout for Faster Switching and Lower On-Resistance
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Solution Overview
Problem
Gallium nitride devices based on current production processes suffer from a 'current collapse' effect, leading to increased on-resistance, reduced switching speed, and decreased reliability due to lattice mismatch and thermal expansion issues between the substrate and GaN epitaxial layer, which affects the formation of a self-supporting structure.
Innovation Solution
A gallium nitride device with a P-GaN layer of a strip structure and alternately distributed first and second structural intervals for the drain metal, where the drain metal is in contact with the P-GaN layer for local hole injection and forms ohmic contact with the AlGaN layer for current conduction, reducing intrinsic on-resistance and avoiding the need for a discontinuous P-GaN structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a discontinuous P-GaN structure is used for hole injection, then hole injection efficiency is improved, but manufacturing complexity and etching precision requirements increase
Solution Approach 1:
The drain metal is segmented into first structural intervals (contacting only P-GaN for hole injection) and second structural intervals (contacting AlGaN for current conduction), allowing different functional regions within a single continuous structure
Solution Approach 2:
The drain metal structure performs multiple functions simultaneously: it provides hole injection through intervals contacting P-GaN and current conduction through intervals contacting AlGaN, eliminating the need for separate discontinuous P-GaN structures
2Reliability
If discontinuous P-GaN structure is etched precisely, then hole injection efficiency is improved, but manufacturing difficulty increases
Solution Approach 1:
Instead of creating discontinuous P-GaN structures through complex etching, the invention inverts the approach by using a continuous P-GaN layer with selectively positioned drain metal intervals, transferring the structural complexity from the semiconductor layer to the metal layer which is easier to manufacture
Solution Approach 2:
The drain metal structure acts as an intermediary that achieves the functional effect of discontinuous P-GaN structures without requiring actual discontinuity in the P-GaN layer, simplifying the manufacturing process
3Reliability
If drain metal contacts only P-GaN for hole injection, then hole injection efficiency is improved, but on-resistance increases
Solution Approach 1:
The drain metal is divided into functionally distinct intervals: first intervals for hole injection (contacting only P-GaN) and second intervals for low-resistance current conduction (contacting AlGaN), optimizing both hole injection and electrical conductivity
Solution Approach 2:
Different regions of the drain metal have different contact configurations tailored to their specific functions: intervals over P-GaN regions provide hole injection while intervals over AlGaN regions provide low-resistance current paths
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 solution enhances switching speed, reduces driving loss, and improves reliability by ensuring efficient hole injection and current conduction while simplifying the production process by eliminating the need for precise etching of the P-GaN layer into a discontinuous structure.
Implementation Method 1
the drain metal is in contact with the P-GaN layer and forms ohmic contact with the AlGaN layer
Implementation Method 2
The P-GaN layer is formed on the AlGaN layer by etching the P-GaN layer on the AlGaN layer
Data Source
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AI summary
Embodiments of this application provide a gallium nitride device, a switching power transistor, a drive circuit, and a gallium nitride device production method. A drain of the gallium nitride device includes a P-GaN layer (500) and a drain metal (M). The P-GaN layer is formed on an AlGaN layer (400), and is of a strip structure in a gate width direction (A) of the device. The drain metal includes a plurality of first structural intervals (610) and a plurality of second structural intervals (620). The plurality of first structural intervals and the plurality of second structural intervals are alternately distributed in the gate width direction. In the first structural intervals, the drain metal is in contact with the P-GaN layer but not with the AlGaN layer; and in the second structural intervals, the drain metal is in contact with the P-GaN layer and forms ohmic contact with the AlGaN layer. In this way, the drain metal implements local injection of holes for the device in the first structural intervals, and forms ohmic contact (Ohmic contact) in the second structural intervals, implementing current conduction from a drain to a source of the device. Therefore, while efficiency of hole injection at P-GaN is ensured, the device does not have an excessively large intrinsic on-resistance, thereby increasing a switching speed of the device, reducing a driving loss of the device, and improving reliability of the device.