GaN MOS Interface Passivation for Stable High-Temperature Annealing
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Solution Overview
Problem
Nitride semiconductor devices with MOS structure face issues due to dangling bonds at the GaN/SiO2 interface, leading to reduced carrier mobility and electrical properties, as hydrogen termination is unstable under high temperature annealing, causing desorption and generation of spatially localized interface-states.
Innovation Solution
Terminating dangling bonds at the GaN/SiO2 interface with atoms or molecules like fluoride (F), chloride (Cl), hydroxyl (OH) groups, or cyano (CN) groups, which form stronger bonds with gallium atoms than hydrogen, preventing the generation of bandgap-states and ensuring high conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrogen termination is used to terminate dangling bonds at the GaN/SiO2 interface, then inter-electrode leakage is reduced, but under high temperature annealing the hydrogen atoms desorb from gallium atoms causing generation of dangling bonds and interface-states
Solution Approach 1:
The invention changes the chemical species used for termination from hydrogen to atoms or molecules with stronger bonding capability to gallium (such as fluoride, chloride, hydroxyl, or cyano groups). This parameter change in the terminating species resolves the contradiction by providing both effective leakage reduction and thermal stability during annealing processes.
Solution Approach 2:
The invention replaces the unstable hydrogen termination (which desorbs under heat) with more stable terminating species that remain bonded to gallium atoms during high temperature annealing. These stable terminations act as permanent passivation layers that do not decompose or desorb under processing conditions, thereby maintaining interface quality throughout manufacturing.
2Ease of manufacture
If SiO2 film is deposited by CVD method, then insulating film formation is achieved, but the film has low density requiring high temperature annealing which causes hydrogen desorption
Solution Approach 1:
The invention applies preliminary termination of dangling bonds with stable species (fluoride, chloride, hydroxyl, or cyano groups) before the high temperature annealing process. This preliminary action ensures that when annealing is subsequently performed to densify the CVD-deposited SiO2 film, the interface remains protected from hydrogen desorption and interface-state generation, thus allowing the annealing to proceed without compromising interface quality.
3Device complexity
If dangling bonds are not terminated, then interface simplicity is maintained, but spatially localized interface-states are generated in the bandgap acting as carrier traps reducing electrical properties
Solution Approach 1:
The invention changes the termination species from simple hydrogen to atoms or molecules with one electron deficient from allowed number (such as F, Cl, OH, or CN groups). These species form stronger bonds with gallium atoms and effectively passivate dangling bonds without introducing additional complexity to the interface structure, thereby maintaining simple interface geometry while dramatically improving electrical properties by eliminating carrier traps.
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
Prevents the generation of bandgap-states near the interface, maintaining strong bond stability even after annealing, thereby enhancing carrier mobility and electrical characteristics of nitride semiconductor devices.
Implementation Method 1
the terminating species has an outermost electron shell in which one electron is deficient from an allowed number of outermost electrons, and is an atom or molecule having stronger bond to the gallium atom than a hydrogen atom
Implementation Method 2
an amount of bonds between the gallium atoms and the oxygen atoms is greater than an amount of bonds between the Ga atoms and the other constituent atoms
Data Source
AI summary
A nitride semiconductor device includes a GaN-based semiconductor layer; and an insulating film provided on a first surface of the GaN-based semiconductor layer, the insulating film containing O atoms, and other constituent atoms other than O. An interface between the GaN-based semiconductor layer and the insulating film has a terminating species which terminates a dangling bond of a Ga atom, the terminating species has an outermost electron shell in which one electron is deficient from an allowed number of outermost electrons, and is an atom or molecule having stronger bond to the Ga atom than a H atom, an amount of Ga—O bonds is greater than an amount of bonds between the Ga atoms and the other constituent atoms.