High Band-Gap Buffer for III-V Transistor Leakage Control

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Solution Overview

Problem

In non-planar transistors, particularly short channel III-VNMOS trigate devices, sub-structure leakage is challenging due to high mobility materials with low band gap and high conductivity, where existing doping solutions are inefficient for short channel transistors.

Innovation Solution

A high band-gap sub-structure is formed between the active channel and the substrate, with a portion extending into the gated region, using epitaxial growth of low band-gap III-V materials to create a conduction band offset and reduce leakage, while terminating lattice mismatch defects below the active channel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If high mobility materials with low band gap are used in the active channel, then electron mobility is improved, but sub-structure leakage increases

Engineering Contradiction:

Improveelectron mobilityVSAvoidsub-structure leakage

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The channel structure is segmented into distinct regions: a first channel region with high mobility low band gap material and a second channel region with lower mobility high band gap material. This segmentation allows the first region to provide high electron mobility while the second region provides leakage suppression, resolving the contradiction between mobility and leakage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different materials with different properties are used in different spatial locations within the channel. The low band gap material is placed where high mobility is needed, while the high band gap material is placed where leakage control is critical, particularly extending into the gated region. This local differentiation resolves the contradiction by optimizing each region for its specific function.

Inventive Principle:

Principle #3Local quality

2Object-generated harmful factors

If existing doping solutions are applied to reduce leakage, then leakage is reduced, but they are inefficient for short channel transistors

Engineering Contradiction:

ImproveleakageVSAvoidshort channel control efficiency

Core Design Contradiction:

Object-generated harmful factorsVSProductivity

Solution Approach 1:

Instead of relying on doping concentration changes, the invention changes the fundamental material parameter (band gap) by introducing a high band gap material region. This parameter change provides more effective leakage control in short channel devices where traditional doping approaches fail, directly addressing the inefficiency of existing solutions.

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If transistor size is reduced for miniaturization, then device density increases, but leakage control becomes more difficult

Engineering Contradiction:

Improvetransistor sizeVSAvoidleakage control

Core Design Contradiction:

Volume of moving objectVSObject-generated harmful factors

Solution Approach 1:

The high band gap material extends vertically into the gated region, utilizing the vertical dimension to provide leakage control path. This dimensional approach allows effective leakage suppression even as the horizontal transistor dimensions are reduced for miniaturization, maintaining control despite size reduction.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 decreases leakage by three orders of magnitude, ensures better short channel control, and maintains electron mobility, leading to improved transistor performance by allowing complete depletion of the active channel and suppressing source-to-drain leakage.

Implementation Method 1

using epitaxial growth of low band-gap III-V materials to create a conduction band offset and reduce leakage

Methodology Applied

Scientific EffectConduction band offset:

Implementation Method 2

using epitaxial growth of low band-gap III-V materials to create a conduction band offset

Methodology Applied

Scientific EffectEpitaxial growth: Epitaxy

Implementation Method 3

while terminating lattice mismatch defects below the active channel

Methodology Applied

Scientific EffectLattice mismatch defect termination:

Data Source

PatentUS10461193B2Apparatus and methods to create a buffer which extends into a gated region of a transistor

Publication Date: 2019.10.29 INTEL CORP

AI summary

Transistor devices may be formed having a buffer between an active channel and a substrate, wherein the active channel and a portion of the buffer form a gated region. The active channel may comprise a low band-gap material on a sub-structure, e.g. the buffer, between the active channel and the substrate. The sub-structure may comprise a high band-gap material having a desired conduction band offset, such that leakage may be arrested without significant impact on electron mobility within the active channel. In an embodiment, the active channel and the sub-structure may be formed in a narrow trench, such that defects due to lattice mismatch between the active channel and the sub-structure are terminated in the sub-structure.