HEMT Breakdown Voltage via Substrate Extraction
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Solution Overview
Problem
The existing methods for increasing the breakdown voltage of high electron mobility transistors (HEMTs) by forming thicker gallium nitride (GaN) layers are time-consuming, reducing productivity, and existing packaging processes are complex due to the presence of a silicon substrate under the channel layer.
Innovation Solution
A HEMT design without a silicon substrate under the channel layer, featuring a stack of buffer, channel, and channel supply layers with strategically placed contact pads on both sides, allowing for simplified packaging using existing processes and achieving high breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thicker GaN layer is formed to increase breakdown voltage, then breakdown voltage is improved, but manufacturing time increases and productivity decreases
Solution Approach 1:
The patent removes the silicon substrate from the HEMT structure to eliminate the need for thick GaN layer formation. By extracting the substrate that caused the technical contradiction, the invention achieves high breakdown voltage without the penalty of extended manufacturing time, as the active device layers can be formed thinner while maintaining performance.
Solution Approach 2:
The invention changes the structural parameters of the HEMT by removing the silicon substrate and adjusting the configuration of contact pads and carrier wafer. This parameter change allows the device to achieve high breakdown voltage through field plate effects and optimized contact geometry rather than relying solely on increased GaN layer thickness.
2Ease of manufacture
If a silicon substrate is present under the channel layer, then existing manufacturing processes can be used, but packaging process becomes complex
Solution Approach 1:
The patent extracts the silicon substrate from the HEMT structure, replacing it with a carrier wafer configuration. This removal simplifies the packaging process by eliminating the complex multi-layer substrate structure, allowing for more straightforward device integration and packaging while maintaining manufacturing feasibility through alternative support structures.
3Ease of manufacture
If contact pads are placed only on one side of the device, then manufacturing is simpler, but electrical connection efficiency is reduced
Solution Approach 1:
The patent transitions from a single-sided contact pad configuration to a multi-dimensional arrangement by placing contact pads on both the front and back sides of the device. This dimensional change allows for optimized electrical connections with reduced parasitic inductance while maintaining manufacturing feasibility through systematic contact pad positioning on multiple surfaces.
Data Source
AI summary
According to example embodiments, a high electron mobility transistor (HEMT) includes: stack including a buffer layer, a channel layer containing a two dimensional electron gas (2DEG) channel, and a channel supply layer sequentially stacked on each other, the stack defining a first hole and a second hole that are spaced apart from each other. A first electrode, a second electrode, and third electrode are spaced apart from each other along a first surface of the channel supply layer. A first pad is on the buffer layer and extends through the first hole of the stack to the first electrode. A second pad is on the buffer layer and extends through the second hole of the stack to the second electrode. A third pad is under the stack and electrically connected to the third electrode.