Gate-All-Around Transistor With Local Oxide Insulator

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Solution Overview

Problem

The challenge lies in efficiently fabricating non-planar transistors while managing short channel and heating effects, as existing technologies face limitations in manufacturability and increased power consumption due to leakage currents and heat dissipation issues in semiconductor devices.

Innovation Solution

The approach involves forming a non-planar semiconductor device with a local silicon on insulator (SOI) structure, where the device body is insulated from the silicon substrate, but the source and drain regions are not, using a trench etched in the silicon with a thick silicon dioxide, nitride, and rare earth metal oxide layers to reduce capacitive coupling and allow heat dissipation, while forming nanowires for the gate region to enhance performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If silicon on insulator (SOI) technology is used to reduce short channel effects, then short channel effects are reduced, but heat dissipation becomes problematic as heat cannot transport to the back of the silicon substrate

Engineering Contradiction:
Improveshort channel effects reductionVSAvoidheat dissipation
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent segments the insulator structure by creating localized oxide regions beneath the channel area rather than a continuous insulator layer across the entire device. This segmentation allows heat to dissipate through the substrate in non-channel regions while maintaining electrical isolation where needed, thus resolving the contradiction between short channel effect reduction and heat dissipation.

Inventive Principle:
Principle #1Segmentation

2Reliability

If non-planar transistors are fabricated to reduce short channel effects, then short channel effects are reduced, but manufacturing complexity increases

Engineering Contradiction:
Improveshort channel effects reductionVSAvoidfabrication requirements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by implementing oxide regions only in specific locations beneath the channel area rather than uniformly across the entire transistor structure. This localized approach provides the necessary electrical isolation and short channel effect control only where required, while maintaining simpler fabrication processes compared to fully three-dimensional non-planar structures.

Inventive Principle:
Principle #3Local quality

3Productivity

If transistor dimensions are decreased to increase performance and functionality, then performance and functionality increase, but leakage current increases

Engineering Contradiction:
Improveperformance and functionalityVSAvoidleakage current
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent implements preliminary anti-action by pre-positioning oxide regions beneath the channel area before transistor operation. These pre-placed insulator regions create potential barrier structures that actively counteract leakage current effects before they can occur during device operation, enabling smaller transistor dimensions with reduced leakage.

Inventive Principle:
Principle #9Preliminary anti-action

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 method effectively reduces short channel effects and heat dissipation issues, improving the manufacturability and power efficiency of non-planar transistors by isolating the gate region from the substrate and allowing heat to dissipate through the bulk silicon substrate, thereby enhancing the performance and reducing power consumption.

Implementation Method 1

a thick silicon dioxide, nitride, and rare earth metal oxide layers to reduce capacitive coupling

Methodology Applied
Scientific EffectCapacitive coupling: Capacitance

Implementation Method 2

allowing heat to dissipate through the bulk silicon substrate

Methodology Applied
Scientific EffectHeat dissipation: Conduction (thermal)

Data Source

PatentEP3516700A1Gate all around device architecture with local oxide
Publication Date: 2019.07.31 ADVANCED MICRO DEVICES INC

AI summary

A device and method for fabricating the non-planar device while managing short channel and heating effects is described. A semiconductor device fabrication process includes forming a non- planar device where the body of the device (610) is insulated from the silicon substrate (105), but the source and drain regions are not insulated from the silicon substrate. The process builds a local silicon on insulator (SOI) while not insulating area around the source and drain regions from the silicon substrate. A trench is etched a length at least that of a channel length of the device while being bounded by a site for a source region and a site for a drain region. The trench is filled with relatively thick layers (110, 205, 305) to form the local SOI. When nanowires (610) of a gate are residing on top of the layer-filled trench, a second trench is etched into the top layer for depositing gate metal (1105) in the second trench.