Composite Oxide Layer for FinFET Dummy Gate Damage Protection

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Solution Overview

Problem

The existing semiconductor fabrication processes often damage insulating layers near gate terminals during the removal of dummy gates, leading to reliability issues such as charge leakage and device failures.

Innovation Solution

The use of two separate oxide layers, where a first oxide layer is formed adjacent to the fin and a second oxide layer is formed after the removal of the dummy gate to cover any damage to the first oxide layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single oxide layer is used during dummy gate removal, then the fabrication process is simple, but the oxide layer is damaged leading to charge leakage and device failures

Engineering Contradiction:

Improvedevice reliabilityVSAvoidoxide layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The oxide layer is divided into two separate layers: a first oxide layer formed before dummy gate deposition and a second oxide layer formed after dummy gate removal. This segmentation allows each layer to serve specific protective functions, with the first layer providing initial protection and the second layer repairing damage from the removal process, thereby resolving the contradiction between reliability and structural complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first oxide layer is formed in advance before the dummy gate is deposited and subsequently removed. This preliminary protective layer is positioned to protect the underlying substrate during the dummy gate removal process, preventing damage before it occurs and improving device reliability without significantly increasing overall process complexity.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If the dummy gate is removed using conventional processes, then the fabrication process is straightforward, but the insulating layers near gate terminals are damaged

Engineering Contradiction:

Improvefabrication processVSAvoiddamage to insulating layers

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The second oxide layer is deposited after dummy gate removal to cushion and repair any damage inflicted on the first oxide layer during the removal process. This compensatory approach maintains ease of manufacture by using standard deposition processes while effectively protecting against harmful effects through the protective function of the two-layer oxide structure.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If no protective oxide layer is present during dummy gate removal, then the process is simple, but charge leakage and device failures occur

Engineering Contradiction:

Improvedevice reliabilityVSAvoidoxide material

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The first oxide layer serves as a sacrificial protective layer that may be partially damaged during dummy gate removal, while the second oxide layer is deposited to recover and restore the protective function. This approach maintains reliability by ensuring a complete protective oxide structure exists after the process, while the quantity of oxide material is optimized through the selective deposition strategy.

Inventive Principle:

Principle #34Discarding and recovering

Data Source

PatentUS12272689B2Semiconductor structure with composite oxide layer

Publication Date: 2025.04.08 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A semiconductor structure and method for fabricating a semiconductor structure includes using two separate oxide layers to improve device reliability. A first oxide layer is formed adjacent a fin (e.g. a fin of a fin field-effect transistor (FinFET) device), a dummy gate is formed adjacent the first oxide layer, the dummy gate is removed, and a second oxide layer is then formed adjacent the first oxide layer. The use of the second oxide layer can improve device reliability by covering any damage that may be inflicted on the first oxide layer when the dummy gate is removed.