Nitride Semiconductor Device With Segmented Electron Transit Layers

Solution Overview

Problem

Semiconductor devices using nitride semiconductors face challenges in achieving low OFF leakage current and low ON resistance, with thick electron transit layers reducing OFF leakage but increasing ON resistance, and thin layers reducing OFF leakage current but increasing ON resistance.

Innovation Solution

A semiconductor device structure with a back barrier layer and multiple electron transit layers of varying thicknesses, where the combined thickness between the source and gate electrodes is greater than between the gate and drain electrodes, and the use of epitaxial growth and specific surface orientations to generate a two-dimensional electron gas (2DEG) selectively, reducing OFF leakage current while maintaining low ON resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If the thickness of the electron transit layer is increased, then OFF leakage current is reduced, but ON resistance increases

Engineering Contradiction:

ImproveOFF leakage currentVSAvoidON resistance

Core Design Contradiction:

Object-generated harmful factorsVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating different thickness regions within the electron transit layer. Specifically, a first electron transit layer with greater thickness is formed in the region between source and gate electrodes to reduce OFF leakage current, while a second electron transit layer with smaller thickness is formed in the region between gate and drain electrodes to maintain low ON resistance. This spatial variation in thickness allows each region to optimize for its specific functional requirement.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The electron transit layer is segmented into multiple distinct layers with different thicknesses. The first electron transit layer (greater thickness) and second electron transit layer (smaller thickness) are formed as separate structural units with different thickness ranges. This segmentation enables independent optimization of each layer's thickness to address the conflicting requirements of OFF leakage suppression and ON resistance reduction.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If the thickness of the electron transit layer is decreased, then ON resistance is reduced, but OFF leakage current increases

Engineering Contradiction:

ImproveON resistanceVSAvoidOFF leakage current

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating different thickness regions within the electron transit layer. Specifically, a first electron transit layer with greater thickness is formed in the region between source and gate electrodes to reduce OFF leakage current, while a second electron transit layer with smaller thickness is formed in the region between gate and drain electrodes to maintain low ON resistance. This spatial variation in thickness allows each region to optimize for its specific functional requirement.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The electron transit layer is segmented into multiple distinct layers with different thicknesses. The first electron transit layer (greater thickness) and second electron transit layer (smaller thickness) are formed as separate structural units with different thickness ranges. This segmentation enables independent optimization of each layer's thickness to address the conflicting requirements of OFF leakage suppression and ON resistance reduction.

Inventive Principle:

Principle #1Segmentation

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 structure effectively suppresses OFF leakage current and maintains low ON resistance, improving the transconductance and withstand voltage between the gate and drain electrodes without increasing the source resistance.

Implementation Method 1

distortion due to the difference in lattice constants of AlGaN and GaN causes piezoelectric polarization or the like in AlGaN, thereby generating a two-dimensional electron gas (2DEG) of high concentration

Methodology Applied

Scientific EffectPiezoelectric polarization: Piezoelectric Effect

Implementation Method 2

a back barrier layer formed of a compound semiconductor over a substrate, a first electron transit layer formed of a compound semiconductor over the back barrier layer

Methodology Applied

Scientific EffectEpitaxial growth: Epitaxy

Data Source

PatentUS11038045B2Semiconductor device

Publication Date: 2021.06.15 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A semiconductor device includes a back barrier layer formed over a substrate, a first electron transit layer formed over the back barrier layer, an opening formed in the first electron transit layer and the back barrier layer, a second electron transit layer formed over the first electron transit layer, a side surface of the first electron transit layer at a side surface within the opening, a side surface of the back barrier layer at a side surface within the opening, and a surface of the back barrier layer at a bottom surface within the opening, an electron supply layer formed over the second electron transit layer, a drain electrode formed over the electron supply layer within the opening, and a gate electrode formed to cover a side surface of the electron supply layer at a side surface within the opening from an edge part of the opening.