Sonic Brush Cleaning to Prevent Wafer Cross-Contamination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor fabrication processes generate organic and inorganic particulate byproducts that contaminate or cross-contaminate wafers, adhering strongly to the back side due to elevated temperatures, causing defects in further processing steps like photolithography and die tape mounting.
Innovation Solution
A sonic cleaning process is used to clean brushes or sponges by immersing them in a liquid cleaning solution bath, where ultrasonic or megasonic vibrations dislodge particles adhering to the cleaning tools, thereby reducing contamination and extending their lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cleaning brush or sponge is used with liquid cleaning agent to remove particles from wafers, then cleaning effectiveness is improved, but the brush or sponge accumulates particles that cause cross-contamination and reduce its longevity
Solution Approach 1:
The patent extracts the harmful particles from the brush/sponge by immersing it in a cleaning vessel where particles are dislodged and removed from the brush surface, separating the contaminant from the cleaning tool to prevent cross-contamination
Solution Approach 2:
The patent implements a process where particles accumulated on the brush are discarded into the cleaning vessel liquid, and the brush is recovered in a cleaned state, extending its usable life and preventing defect generation
2Productivity
If mechanical force is applied through a cleaning brush to remove strongly adhering particles, then particle removal is improved, but the brush wears out faster and requires frequent replacement
Solution Approach 1:
The patent replaces the mechanical cleaning action with a non-contact sonic vibration field that dislodges particles from the brush without mechanical wear, substituting acoustic energy for mechanical force to extend brush life while maintaining cleaning effectiveness
3Productivity
If the cleaning brush is used continuously without cleaning intervals, then processing throughput is maintained, but cross-contamination increases causing wafer defects
Solution Approach 1:
The patent enables continuous operation by implementing an in-line cleaning vessel that cleans the brush between wafer processing steps, maintaining uninterrupted production flow while ensuring the brush remains free of contaminants that would compromise wafer quality
Solution Approach 2:
The patent applies preliminary cleaning action to the brush before it contacts the next wafer, preventing cross-contamination proactively rather than reactively, ensuring each wafer is processed by a clean brush surface
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 sonic cleaning method effectively removes contaminants from brushes or sponges, reducing cross-contamination and doubling their longevity, ensuring cleaner wafers and improved processing efficiency.
Implementation Method 1
A transducer is activated at a frequency which causes cavitation of the cleaning liquid
Implementation Method 2
A transducer is activated at a frequency which causes cavitation of the cleaning liquid in the cleaning vessel
Data Source
AI summary
A method includes cleaning a wafer with a brush element where the brush element collects particles from the wafer during the cleaning process. The brush element is immersed in a first cleaning liquid. An ultrasonic or megasonic vibration is applied to the first cleaning liquid. The ultrasonic or megasonic vibration causes the particles to dislodge from the brush element into the first cleaning liquid. The particles contaminate the first cleaning liquid.