GaN Transistor Chip with AlN Seed Layer for Thermal Isolation
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Solution Overview
Problem
The existing method of mounting silicon devices on printed circuit boards results in the back surface being electrically active, leading to corrosion and increased temperatures, which necessitates the use of insulation with heat sinks, increasing device size and cost by impeding heat conduction.
Innovation Solution
Incorporating an aluminum nitride (AlN) seed layer between the silicon substrate and the AlGaN buffer layer to prevent electrical activity and electrically isolating the sidewalls, allowing direct connection of the heat sink to the back surface without an insulation layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat sink is attached to the back surface of the device, then heat conduction is improved, but insulation must be added which impedes heat conduction and increases device size
Solution Approach 1:
The patent extracts and removes the insulation layer from the device structure by electrically isolating the back surface through doping. This eliminates the need for separate insulation components while maintaining electrical isolation, allowing direct thermal contact between the heat sink and back surface.
Solution Approach 2:
The patent changes the electrical parameter of the back surface by doping it to be electrically inactive. This parameter change allows the back surface to maintain electrical isolation without requiring physical insulation layers, thereby improving heat conduction while preventing corrosion.
2Reliability
If insulation is added to prevent electrical activity on the back surface, then corrosion is reduced, but heat conduction is impeded and device size increases
Solution Approach 1:
The patent changes the electrical parameter of the back surface by doping it to be electrically inactive, which prevents corrosion without requiring insulation layers that would impede heat conduction.
Solution Approach 2:
The patent removes the need for insulation layers by integrating electrical isolation directly into the semiconductor substrate through doping, thereby eliminating the harmful insulation layer that impeded heat conduction.
3Device complexity
If the back surface is electrically active, then device structure is simplified, but corrosion and temperature issues increase
Solution Approach 1:
The patent changes the electrical parameter of the back surface by doping it to be electrically inactive, which prevents corrosion while maintaining a simple device structure without additional insulation components.
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 heat conduction by eliminating the need for insulation, reducing corrosion and temperature issues, and improving humidity resistance, while maintaining effective electrical isolation.
Implementation Method 1
an aluminum nitride (AlN) seed layer between the silicon substrate and the AlGaN buffer layer to prevent the silicon substrate from becoming electrically active
Implementation Method 2
a heat sink 19 attached to the back surface 11 of the silicon substrate 10 to conduct heat away from the back surface 11
Data Source
AI summary
A semiconductor device comprising a silicon substrate, a compound semiconductor material, an insulating material between the silicon substrate and the compound semiconductor material, and a top surface comprising means of electrical connection, and passivation material, where the passivation material is silicon nitride, silicon dioxide, or a combination of both. The present invention eliminates the need for a thick electrical insulator between a heat sink and the back surface of a surface mounted device by the inclusion of an AlN seed layer to electrically isolate the silicon substrate of the device. The sidewalls of the device are also electrically isolated from the active area of the device.