Piezoelectric Atomization for Low-Temperature Precursor Vaporization
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Solution Overview
Problem
High molecular weight precursors with low vapor pressure in semiconductor device fabrication are prone to thermal decomposition and contamination due to design shortcomings in liquid atomization apparatus, leading to by-product formation and substrate contamination.
Innovation Solution
An apparatus and method using a piezoelectric actuator to control liquid flow rate and a compressed gas source to form a droplet aerosol, with a coaxial, radial, or angular flow relationship to reduce thermal decomposition and contamination, featuring a cooled atomization system to maintain low temperatures and prevent clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high molecular weight precursors with low vapor pressure are vaporized using conventional atomization apparatus, then vaporization temperature must be increased, but thermal decomposition and by-product formation occur
Solution Approach 1:
The liquid precursor is divided into fine droplets through atomization, increasing surface area for vaporization. This allows vaporization to occur at lower temperatures by providing more surface area for heat transfer, thereby reducing thermal decomposition of high molecular weight precursors.
Solution Approach 2:
A carrier gas is introduced as an intermediary medium to transport the atomized droplets through the vaporization zone. The carrier gas facilitates heat and mass transfer, enabling efficient vaporization at reduced temperatures and preventing direct contact between liquid precursor and hot chamber walls that would cause decomposition.
2Productivity
If liquid flow passageway is heated to vaporize precursor, then vaporization efficiency increases, but decomposition products accumulate and clog the passageway
Solution Approach 1:
The carrier gas serves as an intermediary that flows through the liquid flow passageway, cooling the walls while transporting atomized droplets. This prevents decomposition products from accumulating and clogging the passageway, maintaining reliable operation while preserving vaporization efficiency.
Solution Approach 2:
The temperature parameter of the liquid flow passageway is changed from high (heated) to low (cooled by carrier gas). This parameter change prevents thermal decomposition in the passageway while the atomization process maintains vaporization efficiency through increased surface area.
3Device complexity
If conventional atomization apparatus is used, then simple design is maintained, but substrate contamination increases due to decomposed material
Solution Approach 1:
The carrier gas acts as a protective intermediary that prevents decomposed material from reaching the substrate. By cooling the liquid flow passageway and transporting droplets efficiently, the carrier gas eliminates the source of contamination while maintaining a relatively simple apparatus design.
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 solution effectively reduces thermal decomposition and by-product formation, maintaining high purity gas/vapor mixtures for thin film deposition, thereby minimizing substrate contamination and increasing product yield.
Implementation Method 1
a piezoelectric actuator to adjust the rate of liquid flow
Implementation Method 2
the gas source conjoins with the liquid, the liquid is atomized to form droplets suspended in the gas forming a droplet aerosol
Implementation Method 3
The droplet aerosol is then heated to form a gas/vapor mixture in a heated vaporization chamber
Implementation Method 4
Heat is transferred indirectly from the heated vaporization chamber walls through the gas, then into the suspended droplets for vaporization
Implementation Method 5
due to the evaporative cooling effect, the surface temperature of an evaporating droplet remains low, further reducing thermal decomposition
Data Source
AI summary
A method for forming a droplet aerosol for vaporization and subsequent thin film deposition on a substrate. The method includes drawing a gas from a compressed gas source and drawing a liquid from a liquid source. The liquid and gas are conjoined in either a coaxial flow relationship or a radial flow relationship or an angular relationship between radial and coaxial flow wherein the gas engages the liquid to form droplets suitable for vaporization and subsequent thin film deposition on a substrate.