Piezoelectric Substrate Cleaning Nozzle Droplet Control
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Solution Overview
Problem
Existing substrate cleaning methods using two-fluid nozzles produce droplets with wide variations in speed and size, leading to inefficient cleaning and potential device damage, as some droplets are ineffective or harmful.
Innovation Solution
A substrate cleaning method and apparatus that control droplet diameter and speed distributions within specific ranges (15-200 μm and 20-100 meters per second) with a standard deviation not exceeding 10%, ensuring consistent and effective droplet discharge for efficient cleaning without damaging the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If two-fluid nozzle is used to produce droplets, then droplet discharge is achieved, but droplet speed and size are distributed over a wide range causing inefficient cleaning and potential device damage
Solution Approach 1:
The patent changes the physical parameters of droplet discharge by using a piezoelectric element to generate ultrasonic vibrations, which controls the droplet diameter and speed distribution. This produces droplets with narrow size distribution (15-200 μm) and controlled speed (20-100 m/s), eliminating the wide parameter distribution caused by two-fluid nozzles and thereby improving both cleaning efficiency and device safety
Solution Approach 2:
The patent replaces the mechanical two-fluid nozzle system with a piezoelectric ultrasonic vibration system. Instead of using compressed gas to atomize liquid, the invention uses piezoelectric elements to generate high-frequency vibrations that produce controlled droplets, thereby achieving narrow parameter distribution and improved reliability
2Area of stationary object
If droplets with wide size distribution are used, then more droplets can cover larger area, but many droplets become useless or harmful causing cleaning inefficiency
Solution Approach 1:
The patent optimizes the droplet diameter parameter to be within 15-200 μm with narrow distribution (3σ ≤ 10% of average). This controlled parameter range ensures that droplets are small enough to be effective for cleaning while maintaining sufficient coverage area, eliminating the waste of oversized droplets that occur with wide distribution
3Productivity
If higher droplet speed is used to improve cleaning effectiveness, then particle removal increases, but risk of device destruction increases
Solution Approach 1:
The patent controls the droplet speed parameter within 20-100 m/s using piezoelectric ultrasonic vibration. This optimized speed range provides sufficient kinetic energy for effective particle removal while preventing excessive speed that would cause device damage, thereby resolving the contradiction between cleaning effectiveness and device safety
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 improves cleaning efficiency by minimizing useless or damaging droplets, ensuring thorough contamination removal without harming the substrate, and allows for faster cleaning processes.
Implementation Method 1
causes a piezoelectric element to expand and contract repeatedly at a frequency of an ultrasonic band, thereby emitting a mist of a cleaning liquid accelerated in one direction from a discharge port toward a substrate at a high speed
Implementation Method 2
causes a piezoelectric element to expand and contract repeatedly at a frequency of an ultrasonic band
Implementation Method 3
Foreign materials such as particles deposited on the substrate are physically removed by the kinetic energy of the droplets of the cleaning liquid
Data Source
AI summary
A valve is closed while a cleaning liquid is fed into a tubular body of a cleaning nozzle, and a piezoelectric element applies vibrations to the cleaning liquid. This causes droplets of the cleaning liquid to be produced and discharged from a plurality of discharge holes. The droplet diameter of the discharged droplets is in the range from 15 to 200 μm, and the distribution of the droplet diameter is such that the value of where a value of 3σ does not exceed 10% of the average droplet diameter. The droplet speed is in the range from 20 to 100 meters per second, and the distribution of the droplet speed is such that the value of where a value of 3σ does not exceed 10% of the average droplet speed. The droplet flow rate is not less than 10 milliliters per minute. Discharging the droplets of the cleaning liquid from the cleaning nozzle toward a substrate while satisfying these discharge conditions improves cleaning efficiency without damages to the substrate.