GaN-HEMT Threshold and Drain Current Balance via Localized Oxidation
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Solution Overview
Problem
GaN high electron mobility transistors (GaN-HEMTs) face challenges in achieving a high threshold while maintaining high drain current, as the formation of oxidized regions with high oxygen concentration near the interface with the gate insulating film either increases the threshold but decreases the drain current or vice versa, depending on the oxidation process used.
Innovation Solution
A semiconductor device with a nitride semiconductor multilayer structure featuring a two-layer aluminum oxide film structure, where the upper aluminum oxide film is formed using an oxygen plasma oxidation process to create a high oxygen concentration region near the gate electrode, and the lower aluminum oxide films are formed using a steam oxidation process to minimize high oxygen concentration in access regions, achieving a balanced high threshold and high drain current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an oxidized region with high oxygen concentration is formed near the interface of the nitride semiconductor layer with the gate insulating film, then the threshold is increased, but the drain current is decreased
Solution Approach 1:
The patent applies local quality by creating different oxygen concentration profiles in different regions of the nitride semiconductor layer. Specifically, a first oxidized region with high oxygen concentration is formed beneath the gate electrode to increase the threshold, while a second oxidized region with low oxygen concentration is formed in the access region to maintain high drain current. This spatial differentiation of oxygen concentration allows simultaneous optimization of both threshold and drain current characteristics.
2Quantity of substance
If no oxidized region is formed near the interface of the nitride semiconductor layer with the gate insulating film, then the drain current is high, but the threshold is decreased
Solution Approach 1:
The patent implements local quality by forming oxidized regions with specifically controlled oxygen concentrations in different spatial locations. The first oxidized region beneath the gate electrode provides the necessary threshold increase, while the second oxidized region in the access region maintains low oxygen concentration to preserve high drain current. This localized control of oxidation states resolves the contradiction between achieving high threshold and maintaining high drain current.
3Reliability
If a gate insulating film is formed on the entire surface of the nitride semiconductor layer using strong oxidizing power, then the C concentration in the gate insulating film is decreased and leak current is suppressed, but the drain current is reduced
Solution Approach 1:
The patent applies local quality by using strong oxidizing power (O2 or O3) selectively only in the region beneath the gate electrode to form the gate insulating film and create a high oxygen concentration oxidized region. In the access region, weak oxidizing power is used to form the gate insulating film with minimal oxidation, preserving low oxygen concentration and maintaining high drain current. This spatially differentiated oxidation approach resolves the contradiction between leak current suppression and drain current maintenance.
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 allows for a positive threshold to be achieved while maintaining high drain current, by forming deeper electron traps under the gate electrode and suppressing electron trap formation in access regions, thus optimizing the performance of GaN-HEMTs.
Implementation Method 1
an oxidized region is formed near an interface of the nitride semiconductor layer with the gate insulating film
Implementation Method 2
formed using O2 or O3 with strong oxidizing power as an oxidizing raw material
Implementation Method 3
formed using H2O with weak oxidizing power as an oxidizing raw material
Data Source
AI summary
A semiconductor device includes: a nitride semiconductor multilayer; an insulating film disposed on the nitride semiconductor multilayer; and a gate electrode disposed on the insulating film, wherein the nitride semiconductor multilayer has a first oxidized region near an interface with a region of the insulating film below the gate electrode, the first oxidized region having an oxygen concentration higher than an oxygen concentration of a region near an interface with a region of the insulating film other than below the gate electrode.