Sidewall Passivation for High Aspect Ratio Cylinder Etch

Solution Overview

Problem

Conventional etching processes for high aspect ratio cylinders in dielectric materials suffer from non-uniform etching profiles due to inadequate sidewall protection, leading to bowed features and compromised structural integrity, as existing fluorocarbon-based processes struggle to form protective polymeric sidewall coatings deep within the cylinders.

Innovation Solution

A method involving the generation of a plasma with an etching reactant to partially etch the feature, followed by pre-treating the substrate to form activated surface groups, and depositing a self-assembled monolayer film as a protective film on the sidewalls, which is repeated until the feature reaches a final depth with an aspect ratio of 5 or greater, preventing lateral etching and maintaining a bow of 20% or less.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If fluorocarbon-based etching processes are used to etch high aspect ratio cylinders, then etching can proceed, but the sidewall protection is inadequate leading to non-uniform etching profiles and bowed features

Engineering Contradiction:

Improveetching profile uniformityVSAvoidsidewall protection adequacy

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by depositing a protective film on the sidewalls of the etched feature before completing the etching process. This protective film is deposited as a self-assembled monolayer that forms activated surface groups on the sidewalls, providing sidewall protection during subsequent etching steps to prevent bowing and maintain uniform profiles in high aspect ratio cylinders

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the chemical parameters of the sidewall protective coating by using a self-assembled monolayer film that forms activated surface groups (such as hydroxyl or carboxyl groups) on the sidewalls. This chemical modification provides better sidewall protection compared to conventional fluorocarbon-based protective coatings, enabling uniform etching profiles in high aspect ratio structures

Inventive Principle:

Principle #35Parameter changes

2Productivity

If deeper etching is performed to increase aspect ratio, then device density improves, but sidewall protection becomes increasingly inadequate

Engineering Contradiction:

Improvedevice densityVSAvoidsidewall protection

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by depositing a protective film on the sidewalls of the etched feature before completing the etching process. This protective film is deposited as a self-assembled monolayer that forms activated surface groups on the sidewalls, providing sidewall protection during subsequent etching steps to prevent bowing and maintain uniform profiles in high aspect ratio cylinders

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the chemical parameters of the sidewall protective coating by using a self-assembled monolayer film that forms activated surface groups (such as hydroxyl or carboxyl groups) on the sidewalls. This chemical modification provides better sidewall protection compared to conventional fluorocarbon-based protective coatings, enabling uniform etching profiles in high aspect ratio structures

Inventive Principle:

Principle #35Parameter changes

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 ensures uniform etching profiles by providing deep sidewall protection, reducing bowing and maintaining high aspect ratios, thereby improving the structural integrity and uniformity of etched features in semiconductor devices like DRAM and 3D NAND structures.

Implementation Method 1

generating a first plasma including an etching reactant, exposing the substrate to the first plasma, and partially etching the feature in the substrate

Methodology Applied

Scientific EffectPlasma etching: Plasma

Implementation Method 2

pre-treating the substrate includes exposing the substrate to vapor including H2O and/or NH3

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Implementation Method 3

pre-treating the substrate includes exposing the substrate to a pre-treatment plasma

Methodology Applied

Scientific EffectPlasma treatment: Plasma

Implementation Method 4

depositing a protective film on sidewalls of the feature, where the protective film is deposited as a self-assembled monolayer film

Methodology Applied

Scientific EffectSelf-assembly: Self-Assembly

Data Source

PatentUS9997373B2Technique to deposit sidewall passivation for high aspect ratio cylinder etch

Publication Date: 2018.06.12 LAM RES CORP

AI summary

Various embodiments herein relate to methods, apparatus and systems for forming a recessed feature in dielectric material on a semiconductor substrate. Separate etching and deposition operations are employed in a cyclic manner. Each etching operation partially etches the feature. Each deposition operation forms a protective coating on the sidewalls of the feature to prevent lateral etch of the dielectric material during the etching operations. The protective coating may be deposited using methods that result in formation of the protective coating along substantially the entire length of the sidewalls. The protective coating may be deposited using particular reactants having low sticking coefficients in some embodiments. The protective coating may also be deposited using particular reaction mechanisms that result in substantially complete sidewall coating. In some cases the protective coating is deposited using plasma assisted atomic layer deposition or plasma assisted chemical vapor deposition.