FinFET Isolation Trench Filling via Flowable Oxide and Thermal Growth

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The formation of isolation regions in FinFET semiconductor devices faces challenges such as fin bending and cracking issues due to high temperature deposition processes, especially as device dimensions decrease, making it difficult to reliably fill trenches with void-free insulating material and increasing the likelihood of pinch-off problems.

Innovation Solution

A method involving forming a plurality of first trenches to define fins, a wider second trench, filling both with flowable oxide material, removing excess from the wider trench, performing thermal growth to form thermal oxide, and then using chemical deposition to create silicon dioxide insulation, which helps in avoiding fin bending and cracking while ensuring effective filling of trenches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high temperature deposition process is used to form insulating material in trenches, then the trench filling is improved, but fin bending and cracking occur

Engineering Contradiction:

Improvetrench filling qualityVSAvoidfin bending and cracking

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the temperature parameter of the deposition process by introducing a thermal annealing step at lower temperature (e.g., 400-600°C) after deposition, which allows the insulating material to settle and densify without causing fin bending or cracking that occurs at high deposition temperatures

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses an intermediary thermal annealing process as a mediator between the deposition step and the final trench filling completion. This intermediate step allows gradual relaxation and densification of the deposited material, preventing direct high-temperature damage to the fins while still achieving complete trench filling

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If device dimensions are decreased to increase density, then integration density is improved, but short channel effects increase

Engineering Contradiction:

Improveintegration densityVSAvoidshort channel effect control

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent transitions from planar FET structure to FinFET three-dimensional structure, where the channel is formed vertically along the fin height rather than horizontally in a planar layer. This dimensional change increases the effective channel area without increasing the footprint area, thereby improving integration density while maintaining better electrostatic control over the channel to reduce short channel effects

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If trench width is reduced to increase device density, then integration density is improved, but pinch-off problems increase

Engineering Contradiction:

Improvedevice densityVSAvoidtrench filling reliability

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent performs preliminary actions before the final trench filling step by first forming the FinFET structure with narrow trenches, then performing thermal annealing to pre-densify and settle the deposited insulating material. This preliminary action prepares the material to flow and fill the narrow trenches completely without pinching off, enabling reliable filling of high-density narrow trenches

Inventive Principle:

Principle #10Preliminary 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 reduces fin bending and eliminates cracking issues, allowing for reliable formation of isolation regions without additional complex process sequences, thereby improving the reliability and efficiency of FinFET device manufacturing.

Implementation Method 1

performing a chemical deposition process to form a deposited silicon dioxide material in the first trenches

Methodology Applied

Scientific EffectChemical Vapor Deposition: Chemical Vapour Deposition

Implementation Method 2

performing a thermal growth process to form a thermal oxide material in the first trenches above the residual portions of the flowable oxide material

Methodology Applied

Scientific EffectThermal Oxidation: Oxidation

Data Source

PatentUS8673723B1Methods of forming isolation regions for FinFET semiconductor devices

Publication Date: 2014.03.18 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

One method includes forming first trenches in a semiconducting substrate to define at least one fin for a FinFET device, forming a second trench in the substrate that is wider than the first trenches, forming a flowable oxide material in the first and second trenches, removing substantially all the flowable oxide material from the second trench and a portion of the flowable oxide material from the first trenches, forming a thermal oxide material in the first trenches above the flowable oxide material and in the second trench, removing substantially all of the thermal oxide material from the second trench and a portion of the thermal oxide material from the first trenches, depositing a silicon dioxide material in the first trenches above the thermal oxide material and in the second trench, removing the silicon dioxide material from the first trenches, and forming a gate structure around the fin of the device.