Wafer Cutting Water Shielding for Blade Corrosion and ESD
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Solution Overview
Problem
The use of mixed water with reduced resistivity to prevent static electricity in wafer cutting can lead to increased carbon dioxide concentration, causing corrosion and wear of the cutting blade, and potential electrostatic discharge damage.
Innovation Solution
A wafer processing method where cleaning water with pure water and carbon dioxide is supplied to the wafer's front surface, and cutting water with pure water alone or lower carbon dioxide concentration is supplied to the cutting blade, using a blade cover to prevent contact between the cutting water and the wafer or blade, while efficiently removing contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mixed water with carbon dioxide is used to reduce resistivity and prevent static electricity, then electrostatic discharge damage is prevented, but the cutting blade undergoes corrosion and wear
Solution Approach 1:
The patent divides the water supply system into two separate streams: cleaning water (with carbon dioxide for static prevention) supplied to the wafer front surface, and cutting water (pure water or low carbon dioxide concentration) supplied to the cutting blade. This segmentation allows each water type to perform its specific function without causing harmful effects to the other component.
Solution Approach 2:
Different water compositions are applied to different locations: the front surface of the wafer receives cleaning water with carbon dioxide for electrostatic prevention, while the cutting blade receives cutting water with low carbon dioxide concentration to prevent corrosion. This local differentiation of water quality resolves the contradiction between static prevention and blade protection.
2Object-generated harmful factors
If pure water is used as cutting water, then the cutting blade is protected from corrosion, but static electricity is generated on the wafer
Solution Approach 1:
The water supply is segmented into two independent systems: one for cleaning the wafer surface with carbon dioxide-containing water to prevent static electricity, and another for cooling the cutting blade with pure water to prevent corrosion. Each system operates independently to avoid the harmful effects of the other.
Solution Approach 2:
Different water compositions are locally applied: pure water or low carbon dioxide water is supplied to the cutting blade area to prevent corrosion, while carbon dioxide-containing water is supplied to the wafer surface to prevent static electricity. This localized quality differentiation resolves the contradiction.
3Ease of operation
If mixed water is used for both cleaning and cutting, then the system is simple to operate, but the cutting blade is corroded and worn
Solution Approach 1:
The water supply system is segmented into two separate channels with different water compositions: one channel supplies cleaning water with carbon dioxide to the wafer surface, and another channel supplies cutting water with low carbon dioxide concentration to the cutting blade. This segmentation maintains operational simplicity while preventing blade corrosion through differentiated water quality.
4Reliability
If cleaning water with high carbon dioxide concentration is supplied to the wafer, then static electricity is prevented, but the cutting blade cannot be protected from corrosion
Solution Approach 1:
The patent implements segmentation of the water supply system where cleaning water with high carbon dioxide concentration is directed exclusively to the wafer front surface for static prevention, while cutting water with low carbon dioxide concentration is directed to the cutting blade for corrosion protection. The blade cover structure physically separates these two water streams to prevent mixing.
Solution Approach 2:
Different water qualities are locally applied to different components: high carbon dioxide concentration water is applied locally to the wafer surface where static prevention is needed, while low carbon dioxide concentration water is applied locally to the cutting blade where corrosion protection is needed. This local quality differentiation resolves the contradiction.
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
Prevents corrosion and wear of the cutting blade and electrostatic discharge by shielding the cutting water from the wafer and blade, ensuring effective cutting and device protection.
Implementation Method 1
pure water mixed with carbon dioxide is supplied to the front surface of the wafer... the concentration of carbon dioxide in the mixed water may be raised, and the acidity of the mixed water may become strong
Implementation Method 2
the cutting water is restrained from contacting the front surface of the wafer by the cleaning water supplied to the front surface of the wafer, whereas the cleaning water is restrained from contacting the cutting blade by the cutting water supplied to the cutting blade
Data Source
AI summary
A wafer processing method includes: a holding step of holding a wafer on a chuck table through a dicing tape; and a dividing step of cutting the wafer along division lines by a cutting blade. In the dividing step, cleaning water including pure water mixed with carbon dioxide is supplied to the front surface of the wafer, and cutting water including pure water alone or pure water mixed with carbon dioxide in a concentration lower than that of the cleaning water is supplied to the cutting blade. During cutting, therefore, the cleaning water and the cutting water are always shielded by each other. Consequently, the cutting blade can be prevented from being corroded or excessively worn due to the cleaning water, and the cutting water can be prevented from contacting the front surface of the wafer to cause electrostatic discharge damage to the devices.