Bubbler Splashguard and Inlet Diffuser for High Vacuum
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Solution Overview
Problem
Existing bubblers in the electronics fabrication industry fail to effectively prevent the transport of liquid droplets and aerosol formation during chemical vapor deposition, leading to erratic mass flow delivery and increased maintenance costs due to partial chemical usage and frequent vessel changes.
Innovation Solution
A bubbler design featuring a diptube inlet with a bubble size reducing outlet and at least one concave downward baffle disc, creating a narrow annular space between the baffle and the bubbler wall to prevent liquid droplets from entering the outlet, combined with a porous diffuser in a sump to ensure vapor delivery under high vacuum and high flowrate conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional splashguard designs are used in bubblers, then liquid droplet prevention is partially achieved, but high vacuum and high flowrate performance deteriorates
Solution Approach 1:
The bubbler system is divided into distinct functional segments: a diptube for gas introduction, a porous diffuser for bubble generation, a baffle disc for droplet separation, and an outlet region. Each segment performs a specific function, allowing the system to maintain high vacuum and flowrate performance while effectively preventing liquid droplets from reaching the outlet
Solution Approach 2:
A baffle disc is introduced as an intermediary element between the liquid chemical precursor and the outlet. This baffle disc, positioned at the outlet, acts as a mediator that allows vapor and carrier gas to pass through while blocking liquid droplets and aerosols, thus resolving the contradiction between droplet prevention and maintaining high flowrate performance
2Productivity
If carrier gas flow rate is increased to improve chemical precursor delivery, then productivity increases, but liquid droplet transport and aerosol formation worsen
Solution Approach 1:
The system creates different local conditions within the bubbler: high-velocity carrier gas flow near the diffuser for efficient precursor pickup, and a low-velocity region near the outlet protected by the baffle disc that allows droplet settling and prevents aerosol formation. This local differentiation allows high productivity without excessive aerosol generation
3Reliability
If bubbler vessel is changed frequently to maintain partial chemical usage, then delivery consistency is maintained, but loss of time and productivity deteriorate
Solution Approach 1:
The improved bubbler design with the baffle disc and porous diffuser enables continuous operation from full to low chemical levels without compromising delivery consistency or generating excessive aerosols. This eliminates the need for frequent vessel changes, maintaining reliable chemical precursor delivery while minimizing downtime and maximizing productivity
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 design prevents splashing and aerosol droplet formation, allowing for continuous use from full to low chemical levels, reducing downtime and particulate generation, and maintaining consistent chemical mass flow delivery.
Implementation Method 1
entraining liquid chemical precursor from the bubbler into the carrier gas
Implementation Method 2
a bubble size reducing outlet, such as a diffuser in a sump
Implementation Method 3
passing the entrained chemical precursor and carrier gas past at least one baffle disc in a narrow annular space between the outer perimeter of the baffle disc and the inner surface of bubbler sidewall
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A bubbler (10) has a diptube inlet (14) ending in a bubble size reducing outlet (18) and at least one baffle disc (22, 24) positioned between the outlet of the diptube and the outlet (16) of the bubbler to provide a narrow annular space between the baffle disc and the wall of the bubbler to prevent liquid droplets from entering the outlet to the bubbler. The bubble size reducing outlet is an elongated cylindrical porous metal frit situated in a sump (21) of approximately the same dimensions. A metal frit (32) is placed at the inlet of the outlet of the bubbler.