GaN HEMT Gate Structure Reducing Leakage via Segmented Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gallium nitride high electron mobility transistors (HEMTs) experience significant gate leakage, leading to low reliability and failure under abnormal operation due to their normally-off circuit design.
Innovation Solution
A method for manufacturing a gate structure for gallium nitride HEMT involving the formation of a channel layer, barrier layer, doped gallium nitride layer, and undoped gallium nitride layer on a substrate, followed by the creation of an insulating layer and a trench, with a mask layer used to etch the gate metal layer and underlying layers, ensuring the insulating layer blocks current leakage and the undoped gallium nitride layer protects the doped gallium nitride layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a normally-off circuit design is adopted in gallium nitride HEMT with high concentration of 2DEG, then the transistor can operate under high power and high frequency conditions, but serious gate leakage occurs causing low reliability and failure under abnormal operation
Solution Approach 1:
The gate structure is segmented into multiple functional layers: an undoped gallium nitride layer (first gate layer) and a doped gallium nitride layer (second gate layer). The undoped layer provides high electron mobility and forms the 2DEG channel, while the doped layer serves as a protective barrier that prevents gate leakage. This segmentation allows each layer to perform its specific function optimally, resolving the contradiction between power handling and reliability.
Solution Approach 2:
The undoped gallium nitride layer is formed before the doped gallium nitride layer to preliminarily establish the high electron mobility channel. This preliminary action ensures that the 2DEG is formed in the correct location with appropriate properties before the protective doped layer is added, which then prevents gate leakage without interfering with the channel formation.
2Ease of manufacture
If the doped gallium nitride layer is exposed during subsequent manufacturing processes, then the gate structure can be formed, but the doped gallium nitride layer is affected by subsequent processes reducing reliability
Solution Approach 1:
Instead of forming the gate structure by directly patterning the doped gallium nitride layer, the invention inverts the approach: the undoped layer is formed first as the primary structure, then the doped layer is formed on top to protect it. Subsequent manufacturing processes pattern the undoped layer through the protective doped layer, which acts as an etch mask. This inversion protects the doped layer from direct exposure to harsh manufacturing processes while still allowing precise gate structure formation.
Solution Approach 2:
The doped gallium nitride layer serves as an intermediary protective barrier between the sensitive doped region and the subsequent manufacturing processes. It acts as an etch mask that protects the doped layer from damage during source and drain formation and other subsequent steps, ensuring the doped layer maintains its protective function without being degraded by manufacturing processes.
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 proposed method significantly reduces gate leakage, enhancing the reliability of gallium nitride HEMTs by effectively blocking current leakage and protecting the doped gallium nitride layer from subsequent manufacturing processes.
Implementation Method 1
forming an insulating layer on the undoped gallium nitride layer... the insulating layer blocks current leakage
Implementation Method 2
By using the mask layer as an etching mask, the exposed gate metal layer and the underlying insulating layer, the undoped gallium nitride layer and the doped gallium nitride layer are removed
Implementation Method 3
a method of forming the channel layer, the barrier layer, the doped gallium nitride layer, and the undoped gallium nitride layer includes, for example, metal organic chemical vapor deposition (MOCVD)
Implementation Method 4
a heterogeneous structure including aluminum gallium nitride (AlGaN) and gallium nitride (GaN) is utilized to generate two-dimensional electron gas (2DEG) having high planar charge density and high electron mobility at the junction therebetween
Data Source
AI summary
A method of manufacturing a gate structure for gallium nitride (GaN) high electron mobility transistor (HEMT) includes orderly forming a channel layer, a barrier layer, a doped GaN layer, an undoped GaN layer, and an insulating layer on a substrate, and then removing a portion of the insulating layer to form a trench. A gate metal layer is formed on the substrate to cover the insulating layer and the trench, and then a mask layer aligned with the trench is formed on the gate metal layer, wherein the mask layer partially overlaps the insulating layer. By using the mask layer as an etching mask, the exposed gate metal layer and the underlying insulating layer, the undoped GaN layer and the doped GaN layer are removed, and then the mask layer is removed.