p-GaN HEMT Gate Ring Isolation Against Parasitic Channels
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Solution Overview
Problem
Existing HEMT devices with p-GaN gates face issues with parasitic channel formation due to lateral ion penetration during ion implantation, leading to defects and reduced performance.
Innovation Solution
The formation of a pGaN gate with a straight first and second gate finger and a semicircular gate arc, followed by an isolation mask covering the gate entirely, allows for precise ion implantation only in inactive regions, minimizing lateral penetration and parasitic channel formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion implantation is performed to form isolation regions in HEMT heterostructure, then inactive regions are formed to control device behavior, but lateral ion penetration occurs causing parasitic channel formation and defects at the sides of HEMTs
Solution Approach 1:
A mask layer is introduced as an intermediary between the ion implantation source and the HEMT heterostructure. This mask layer selectively blocks ions from reaching the active regions and gate structures, allowing ion implantation to occur only in the desired isolation regions. The mask layer thus mediates the ion implantation process to prevent harmful lateral penetration while maintaining the beneficial isolation effects.
Solution Approach 2:
The mask layer is formed on the HEMT heterostructure before the ion implantation process begins. This preliminary action of placing the mask layer protects critical regions in advance, preventing parasitic channel formation before it can occur during the ion implantation process.
2Productivity
If isolation implantation is performed without precise masking, then the process is simpler and faster, but parasitic channels form at the sides of HEMTs reducing device performance
Solution Approach 1:
The mask layer serves as a precise intermediary that defines the boundaries between active and inactive regions. By using the mask layer to control ion implantation, sharp interfaces are achieved without requiring complex post-processing steps, thus maintaining both productivity and manufacturing precision.
3Ease of manufacture
If the gate structure uses conventional straight edges, then fabrication is simpler, but ion penetration occurs at the corners creating parasitic channels
Solution Approach 1:
The gate structure incorporates rounded corners instead of sharp 90-degree angles. This curvature modification eliminates the corner regions where lateral ion penetration would create parasitic channels, while maintaining overall gate functionality and requiring minimal additional fabrication complexity.
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 improves the performance of HEMT devices by reducing parasitic channel formation, enhancing the threshold voltage, and maintaining low drain leakage and on-resistance.
Implementation Method 1
An isolation implantation process is then performed in the presence of the mask to implant ions into the portions of the heterostructure exposed by the mask.
Data Source
AI summary
A process for forming a high electron mobility transistor (HEMT) includes forming a semiconductor heterostructure including a channel layer of the HEMT, forming a gate layer of GaN on the channel layer, and patterning the gate layer to form a first gate finger, a second gate finger, and a gate arc connecting the first gate finger and the second gate finger. The process includes forming an isolation mask covering an active region of the semiconductor heterostructure and the gate arc and performing an ion bombardment process on an inactive region of the semiconductor heterostructure exposed by the isolation mask.