Supercritical CO2 Etching Prevents Electrode Leaning

Solution Overview

Problem

Conventional methods for manufacturing DRAM capacitors using sacrificial layers face issues with the leaning of lower electrodes due to the surface tension of etching and cleaning solutions, which can cause structural damage during the etching process.

Innovation Solution

The use of supercritical carbon dioxide as a solvent, combined with etching chemicals like fluoride and pyridine, and cleaning chemicals such as F-AOT and fluorine-based surfactants, to etch and clean silicon oxide layers, thereby preventing the leaning of lower electrodes by maintaining the process conditions above the critical temperature and pressure of carbon dioxide.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional etching and cleaning solutions are used, then the etching process can be performed, but the surface tension of the solutions causes the lower electrodes to lean, resulting in structural damage

Engineering Contradiction:

Improveetching efficiencyVSAvoidstructural integrity of lower electrodes

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the physical state of the cleaning solution from liquid to supercritical fluid by adjusting temperature and pressure parameters above the critical point of carbon dioxide. This parameter change eliminates surface tension while maintaining effective cleaning capability, thus preventing electrode leaning while preserving etching efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the phase transition of carbon dioxide from gas to supercritical fluid state. By controlling the phase transition through temperature and pressure adjustments, the cleaning medium achieves zero surface tension in the supercritical state, solving the electrode leaning problem while maintaining cleaning effectiveness

Inventive Principle:

Principle #36Phase transitions

2Ease of manufacture

If conventional liquid cleaning solutions are used, then cleaning can be performed, but the surface tension causes structural leaning and damage

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidelectrode alignment accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the physical state of the cleaning solution from liquid to supercritical fluid by adjusting temperature and pressure parameters above the critical point of carbon dioxide. This parameter change eliminates surface tension while maintaining effective cleaning capability, thus preventing electrode leaning while preserving etching efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical action of liquid flow (which creates surface tension and pressure on structures) with supercritical fluid diffusion and dissolution mechanisms. This substitution eliminates the mechanical forces that cause electrode leaning while maintaining cleaning effectiveness through molecular-level interaction

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If supercritical carbon dioxide is used as a solvent, then surface tension is eliminated preventing electrode leaning, but the process requires high temperature and pressure conditions

Engineering Contradiction:

Improvestructural integrity of lower electrodesVSAvoidprocess temperature and pressure

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent utilizes the phase transition of carbon dioxide from gas to supercritical fluid state. By controlling the phase transition through temperature and pressure adjustments, the cleaning medium achieves zero surface tension in the supercritical state, solving the electrode leaning problem while maintaining cleaning effectiveness

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The patent uses carbon dioxide, which is inexpensive and readily available, as the supercritical fluid medium. Although high temperature and pressure are required temporarily to achieve the supercritical state, the CO2 can be easily depressurized back to gas state, making the process economically viable despite the temporary extreme conditions

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 significantly enhances the etch rate and prevents structural leaning, achieving faster and more efficient etching and cleaning processes while maintaining the integrity of the semiconductor substrate.

Implementation Method 1

the use of supercritical carbon dioxide as a solvent, combined with etching chemicals like fluoride and pyridine, and cleaning chemicals such as F-AOT and fluorine-based surfactants, to etch and clean silicon oxide layers, thereby preventing the leaning of lower electrodes by maintaining the process conditions above the critical temperature and pressure of carbon dioxide

Methodology Applied

Scientific EffectSupercritical fluid: Supercritical Fluid

Data Source

PatentUS8790470B2Etching, cleaning and drying methods using supercritical fluid and chamber systems using these methods

Publication Date: 2014.07.29 SAMSUNG ELECTRONICS CO LTD

AI summary

Provided herein are etching, cleaning and drying methods using a supercritical fluid, and a chamber system for conducting the same. The etching method includes etching the material layer using a supercritical carbon dioxide in which an etching chemical is dissolved, and removing an etching by-product created from a reaction between the material layer and the etching chemical using a supercritical carbon dioxide in which a cleaning chemical is dissolved. Methods of manufacturing a semiconductor device are also provided.