Carbon Layer Mask for 3D Etching Integrity

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Solution Overview

Problem

In semiconductor manufacturing, the shrinkage of devices to submicron dimensions and increased integration lead to challenges in maintaining mask integrity during plasma etching, resulting in inaccurate pattern formation due to mask erosion by free radicals.

Innovation Solution

A method involving forming a carbon layer on a mask and feature layer, followed by a directional etch process to create openings, where the carbon layer protects the mask and maintains its shape, reducing issues like bowing, top faceting, or tapering of the openings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hard masks are used for etching deep, high aspect ratio features, then the mask can withstand the etching process, but free radicals react with the mask material and erode the mask, affecting pattern accuracy

Engineering Contradiction:

Improvemask integrityVSAvoidpattern accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

A carbon layer is introduced as an intermediary protective coating on the mask surface. This carbon layer acts as a mediator that prevents direct contact between free radicals and the mask material, thereby protecting the mask from erosion while maintaining pattern fidelity during deep high aspect ratio feature etching

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The mask structure is enhanced by combining it with a carbon layer to form a composite structure. This composite material approach allows the mask to benefit from both its original structural properties and the carbon layer's resistance to free radical attack, improving both reliability and manufacturing precision

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If conventional photoresists are used for etching, then the process is simpler, but they cannot withstand deep, high aspect ratio feature etching

Engineering Contradiction:

Improveetching process simplicityVSAvoidmask withstanding capability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The solution combines conventional photoresist masks with a carbon layer to create a composite mask structure. This allows the process to retain the simplicity of photoresist application while gaining the enhanced withstanding capability needed for deep high aspect ratio feature etching through the protective carbon coating

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 effectively reduces profile issues in the openings formed in the feature layer, enhancing the accuracy and integrity of the semiconductor chip manufacturing process.

Implementation Method 1

plasma etching is a form of plasma processing used to fabricate integrated circuits

Methodology Applied

Scientific EffectPlasma etching: Plasma

Implementation Method 2

during the etching process free radicals react with the mask material and erode the mask

Methodology Applied

Scientific EffectFree radicals reaction: Chemical Bonding

Implementation Method 3

forming a carbon layer on the mask and the exposed portion of the feature layer

Methodology Applied

Scientific EffectCarbon layer formation: Deposition (physical)

Data Source

PatentUS11384428B2Carbon layer covered mask in 3D applications

Publication Date: 2022.07.12 APPLIED MATERIALS INC

AI summary

Embodiments of the present disclosure generally relate to a method for forming an opening using a mask. In one embodiment, a method includes forming a mask on a feature layer. The method includes forming a first opening in the mask to expose a portion of the feature layer. The method further includes forming a carbon layer on the mask and the exposed portion of the feature layer. The method also includes removing portions of the carbon layer and a portion of the exposed portion of the feature layer in order to form a second opening in the feature layer.