III-V MOSFET Source-Channel Junction With Graded Bandgap Layers

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Solution Overview

Problem

III-V MOSFETs face performance reduction due to electron energy barriers at the source-channel junction, leading to current choke and increased resistance, which is exacerbated by abrupt junctions between different materials like InGaAs and InP.

Innovation Solution

A source area with multiple portions of III-V layers, such as InGaAsP, is used to smooth the conduction band discontinuity, forming a monotonic sequence of bandgaps that reduces the bandgap difference between adjacent layers and the channel material, thereby lowering leakage and enhancing on-state current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If an abrupt source-channel junction is formed between different III-V materials (e.g., InGaAs and InP), then the device structure is simple and manufacturing is easier, but an electron energy barrier is created causing current choke and reduced performance

Engineering Contradiction:

Improveease of forming source-channel junctionVSAvoidperformance of III-V MOSFET

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The source-channel junction is divided into multiple graded regions with progressively changing composition (e.g., In0.53Ga0.47As, In0.4Ga0.6AsP, In0.2Ga0.8AsP, In0.1Ga0.9AsP) rather than an abrupt interface. This segmentation creates a gradual transition in bandgap and lattice constant, eliminating the electron energy barrier while maintaining manufacturing feasibility through sequential deposition processes

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The composition parameters of the III-V materials are gradually changed across the source-channel junction interface. By varying the indium and phosphorus content in systematic steps, the bandgap and lattice constant transition smoothly, reducing the electron energy barrier from 0.2 eV to nearly zero while preserving ease of manufacture through controlled parameter gradients

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a monotonic sequence of bandgaps is implemented in the source area portions, then leakage is reduced and on-state current is enhanced, but the device structure becomes more complex

Engineering Contradiction:

Improveperformance of III-V MOSFETVSAvoidcomplexity of source area structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Different portions of the source area are assigned different material compositions with specific bandgaps tailored to their local function. The first portion has a larger bandgap for lower leakage, while subsequent portions have progressively smaller bandgaps for better carrier injection, creating local quality variations that optimize performance without requiring complex overall device architecture

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The source area is constructed as a composite structure of multiple III-V material layers (InGaAs, InGaAsP with varying compositions) rather than a single material. This composite approach enables the monotonic bandgap sequence that reduces leakage and enhances on-state current while maintaining a relatively simple layered structure that can be fabricated using standard molecular beam epitaxy processes

Inventive Principle:

Principle #40Composite materials

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 reduces source/drain resistance and improves the performance of III-V MOSFETs by smoothing the source-channel junction, leading to higher on-state current and lower leakage, while maintaining the same lattice constant across materials.

Implementation Method 1

A bandgap of a channel material and bandgaps of the multiple portions form a monotonic sequence of bandgaps

Methodology Applied

Scientific EffectBandgap engineering:

Implementation Method 2

smooth the conduction band discontinuity, forming a monotonic sequence of bandgaps that reduces the bandgap difference between adjacent layers

Methodology Applied

Scientific EffectConduction band discontinuity smoothing:

Data Source

PatentUS11756998B2Source-channel junction for III-V metal-oxide-semiconductor field effect transistors (MOSFETs)

Publication Date: 2023.09.12 INTEL CORP

AI summary

Embodiments herein describe techniques, systems, and method for a semiconductor device. Embodiments herein may present a semiconductor device having a channel area including a channel III-V material, and a source area including a first portion and a second portion of the source area. The first portion of the source area includes a first III-V material, and the second portion of the source area includes a second III-V material. The channel III-V material, the first III-V material and the second III-V material may have a same lattice constant. Moreover, the first III-V material has a first bandgap, and the second III-V material has a second bandgap, the channel III-V material has a channel III-V material bandgap, where the channel material bandgap, the second bandgap, and the first bandgap form a monotonic sequence of bandgaps. Other embodiments may be described and/or claimed.