InAlGaN HEMT Gate Insulating Structure Against Etching Damage
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Solution Overview
Problem
Nitride semiconductor-based high electron mobility transistors (HEMTs) face performance deterioration due to damage during the manufacturing process, particularly for barrier layers containing indium, aluminum, and gallium, which can lead to increased leakage current and defects from etching, compromising device performance.
Innovation Solution
A semiconductor device design featuring a three-layer insulating structure with silicon nitride (SiN) and silicon aluminum nitride (SiAlN) films between the barrier layer and the gate electrode, where the second insulating film acts as an etching stopper to prevent exposure and damage to the barrier layer, and the films are continuously formed without exposure to the atmosphere to minimize defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier layer containing In, Al, and Ga is used to improve electron supply capability, then device performance is enhanced, but the barrier layer becomes vulnerable to etching damage and In desorption
Solution Approach 1:
An insulating layer comprising multiple films (first insulating film, second insulating film, and third insulating film) is introduced as an intermediary between the barrier layer and gate electrode. This insulating layer acts as a protective mediator that prevents direct exposure of the barrier layer to etching processes, thereby eliminating etching damage and In desorption while preserving the high-performance characteristics of the InAlGaN barrier layer.
Solution Approach 2:
The insulating layer is formed on the barrier layer before any etching processes are performed. This preliminary protective action ensures that the barrier layer is already shielded when subsequent etching steps are carried out, preventing etching damage and In desorption from occurring in the first place.
2Ease of manufacture
If the barrier layer is exposed to etching processes, then manufacturing steps can be completed, but leakage current increases due to bond breakage and In desorption
Solution Approach 1:
The insulating layer serves as a protective intermediary that allows manufacturing processes to proceed without exposing the barrier layer to harmful etching. The gate electrode can still be formed through the insulating layer via opening formation, maintaining manufacturing feasibility while preventing leakage current generation.
Solution Approach 2:
The insulating layer is deposited beforehand to cushion and absorb the harmful effects of etching processes. This protective cushioning prevents direct contact between etching chemicals and the barrier layer, thereby preventing bond breakage and In desorption that would otherwise lead to increased leakage current.
3Device complexity
If a single-layer insulating structure is used between barrier layer and gate electrode, then device structure is simple, but insufficient protection against etching damage occurs
Solution Approach 1:
The insulating layer is segmented into multiple films with distinct functions: the first insulating film provides initial protection, the second insulating film (with different etching resistance) enables selective opening formation, and the third insulating film provides final protection. This segmentation allows each layer to be optimized for its specific function, achieving superior protection while maintaining reasonable structural complexity.
Solution Approach 2:
The insulating structure uses composite materials with different properties - films comprising different oxides or nitrides with varying etching resistance characteristics. This composite approach allows the structure to provide both protection and manufacturability, as the varying etching resistance enables selective removal of specific layers during gate electrode formation.
Data Source
AI summary
A semiconductor device includes: a channel layer that includes a first nitride semiconductor that contains Ga; a barrier layer that is provided on a first surface side of the channel layer, and includes a second nitride semiconductor that contains In, Al, and Ga; a source electrode and a drain electrode that are provided on a second surface side of the barrier layer opposite to the channel layer side; a gate electrode that is provided between the source electrode and the drain electrode, on the second surface side of the barrier layer; and an insulating layer that is provided between the second surface of the barrier layer and the gate electrode.