Liquid Precursor Atomization for Thin Film Deposition
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Solution Overview
Problem
High molecular weight precursors with low vapor pressure in semiconductor fabrication often undergo thermal decomposition when vaporized, leading to by-product formation and contamination in the atomization apparatus, which can result in substrate defects and yield loss.
Innovation Solution
An atomization apparatus that uses a carrier gas to form a droplet aerosol, which is then heated in a vaporization chamber, with design features such as a thin-walled tubular member and extended heat exchanger or thermoelectric cooler to minimize temperature increase and prevent thermal decomposition, allowing for efficient vaporization of high molecular weight substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high molecular weight precursors with low vapor pressure are vaporized at high temperatures, then vaporization efficiency is improved, but thermal decomposition occurs leading to by-product formation
Solution Approach 1:
The liquid precursor is segmented into fine droplets through atomization before vaporization. This increases the surface area to volume ratio, enabling efficient vaporization at lower temperatures and reducing thermal decomposition. The segmentation transforms a bulk heating problem into a surface-dominated evaporation process.
Solution Approach 2:
The invention changes the physical state parameters by atomizing the liquid into droplets with controlled size distribution. This parameter change allows the system to achieve high vaporization efficiency without requiring excessively high temperatures, thereby preventing thermal decomposition of heat-sensitive high molecular weight precursors.
2Productivity
If the liquid flow passageway is heated to enable vaporization, then vapor generation is improved, but decomposition products accumulate and clog the passageway
Solution Approach 1:
The invention extracts the heating function from the liquid flow passageway by introducing a separate heated carrier gas stream. The liquid is atomized and vaporized in the heated gas flow rather than being heated through the passageway walls, eliminating the clogging problem while maintaining vapor generation efficiency.
Solution Approach 2:
A heated carrier gas acts as an intermediary medium to transfer thermal energy to the atomized liquid droplets. This intermediary approach allows vaporization to occur without direct heating of the liquid through the passageway, preventing decomposition product accumulation and clogging.
3Speed
If direct liquid injection onto hot metal surface is used, then vaporization speed is improved, but thermal decomposition occurs due to direct contact
Solution Approach 1:
The invention introduces a carrier gas as an intermediary between the hot metal surface and the liquid precursor. The carrier gas is heated by the metal surface and then used to vaporize the atomized liquid, eliminating direct contact between the liquid and hot metal while maintaining rapid vaporization through the hot gas environment.
Solution Approach 2:
The invention uses pneumatic atomization where pressurized carrier gas both atomizes the liquid and serves as the heating medium. This dual pneumatic function replaces direct liquid-to-metal contact, achieving fast vaporization without thermal decomposition.
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
The apparatus effectively reduces thermal decomposition and by-product formation, maintaining high purity gas/vapor mixtures for thin film deposition, thereby reducing substrate contamination and increasing product yield.
Implementation Method 1
The precursor liquid is atomized by a carrier gas to form a droplet aerosol comprised of small droplets suspended in the gas
Implementation Method 2
Heat is transferred indirectly from the heated vaporization chamber walls through the gas, then into the suspended droplets for vaporization
Implementation Method 3
The droplet aerosol is then heated to form a gas/vapor mixture in a heated vaporization chamber
Implementation Method 4
due to the evaporative cooling effect, the surface temperature of an evaporating droplet remains low, further reducing thermal decomposition that can occur in the liquid phase at sufficiently high temperatures
Data Source
AI summary
A method for atomizing a precursor liquid for vapor generation and thin film deposition on a substrate. The precursor liquid is atomized by a carrier gas to form a droplet aerosol composed of small precursor liquid droplets suspended in the carrier gas. The droplet aerosol is then heated to form vapor, producing a gas/vapor mixture that can be introduced into a deposition chamber to form thin films on a substrate. The liquid is introduced into the atomizing apparatus in such a manner as to avoid excessive heating that can occur or lead to the formation of undesirable by-products due to material degradation as result of thermal decomposition. The method is particularly suited for vaporizing high molecular weight substances with a low vapor pressure that requires a high vaporization temperature for the liquid to vaporize. The method can also be used to vaporize solid precursors dissolved in a solvent for vaporization.