Nitride Semiconductor Device Si-H Bond Control
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Solution Overview
Problem
Nitride semiconductor devices with silicon nitride films suffer from increased leakage current under high temperature and high voltage stress, limiting their use as switching devices over long periods.
Innovation Solution
A nitride semiconductor device with a silicon nitride insulating film having a concentration of Si—H bonds equal to or less than 6.0×10^21 cm−3, and a multilayer structure including a first and second insulating film with specific bond concentrations and refractive indices, annealed at 800° C. or higher to suppress current collapse and leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high concentration of Si—H bonds is used in SiN film to suppress current collapse, then current collapse suppression is enhanced, but leakage current increases
Solution Approach 1:
The insulating film is segmented into two layers with different Si—H bond concentrations. The first layer has lower concentration (5.0×10^21 cm−3 or less) to minimize leakage current, while the second layer has higher concentration (8.0×10^21 cm−3 or less) to provide current collapse suppression. This segmentation resolves the contradiction by distributing the functional requirements across different layers.
Solution Approach 2:
The insulating film structure functions as a composite material system where two layers with different Si—H bond concentrations work together. The combination of lower and higher concentration layers creates a composite structure that achieves both low leakage current and effective current collapse suppression, overcoming the limitations of using a single concentration level.
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 solution effectively prevents leakage current from exceeding five times its initial value during high temperature and high voltage stress tests, enabling the nitride semiconductor device to be used as a reliable switching device for extended periods.
Implementation Method 1
it is known that a phenomenon called a current collapse occurs in which on-resistance changes when a voltage is applied to a field effect transistor using two-dimensional electron gas (2 DEG) generated on a hetero interface of a nitride semiconductor multilayer structure
Implementation Method 2
The SiN film with a high effect of suppressing the current collapse has a defect in that current leaks. Accordingly, an idea has been proposed that the SiN film laminated on the surface of the nitride semiconductor has a two-layer structure including a layer which contains a large amount of hydrogen and has a function of suppressing the current collapse, and a layer which contains less hydrogen and has a function of suppressing the leakage current.
Implementation Method 3
a first insulating film and a second insulating film which are different from each other in concentration of Si—H bonds, and each of which is formed of silicon nitride, are laminated on a surface of a nitride semiconductor multilayer structure
Data Source
AI summary
A nitride semiconductor device includes a substrate; a nitride semiconductor multilayer structure which is formed on the substrate, includes a first nitride semiconductor layer and a second nitride semiconductor layer having a different composition from that of the first nitride semiconductor layer, and generates two dimensional electron gas on a hetero interface between the first nitride semiconductor layer and the second nitride semiconductor layer; and an insulating film which covers at least a portion of a surface of the nitride semiconductor multilayer structure, has a concentration of Si—H bonds equal to or less than 6.0×1021 cm−3, and is formed of silicon nitride.