Wire Saw Slurry Viscosity Control via Water Content
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Solution Overview
Problem
Existing wire sawing processes for semiconductor wafers result in deteriorating slurry properties over time, leading to poor quality wafers with visible wire orientation structures, requiring frequent slurry replacement and additional machining steps.
Innovation Solution
A wire saw system that controls the water content of the gaseous medium surrounding the slurry, maintaining a predetermined water level to stabilize viscosity and prevent non-Newtonian behavior, allowing for extended slurry use without adverse effects on wafer quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If slurry is used for extended wire sawing operations, then productivity increases, but slurry viscosity increases and wafer quality deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the water content of the gaseous medium to regulate slurry viscosity during extended wire sawing operations. By adjusting the water content parameter of the atmosphere surrounding the slurry, the system maintains optimal viscosity levels even during prolonged use, preventing the viscosity increase that would otherwise lead to wire orientation structures on wafer surfaces and quality deterioration.
2Productivity
If slurry is used for extended wire sawing operations, then productivity increases, but slurry viscosity becomes uncontrolled
Solution Approach 1:
The patent implements feedback control by monitoring and controlling the water content of the gaseous medium that contacts the slurry. This feedback mechanism ensures that slurry viscosity remains stable during extended wire sawing operations. The controlled water content prevents uncontrolled viscosity changes, allowing the slurry to maintain its functional properties throughout prolonged use and enabling extended operational cycles without replacement.
3Manufacturing precision
If frequent slurry replacement is performed, then wafer quality is maintained, but productivity decreases
Solution Approach 1:
The patent resolves this contradiction by changing the environmental parameter (water content of gaseous medium) to maintain slurry performance. This allows continuous use of the same slurry for extended periods while maintaining wafer surface quality free of wire orientation structures. The parameter control eliminates the need for frequent slurry replacement, thereby maintaining high productivity alongside quality standards.
4Stability of the object's composition
If slurry viscosity is increased to prevent non-Newtonian behavior, then flow stability improves, but wire sawing performance deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the water content of the gaseous medium to maintain optimal slurry viscosity levels. This approach achieves flow stability and prevents non-Newtonian behavior without requiring excessive viscosity increases that would harm wire sawing performance. The controlled water content allows the slurry to maintain the right balance between stability and cutting efficiency throughout extended operations.
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 controlled water content system ensures consistent wafer quality, reduces the need for frequent slurry replacement, and allows for higher feed rates while maintaining long-term cutting process stability and structure-free surfaces.
Implementation Method 1
a device for establishing a predetermined water content in at least part of a gaseous medium coming into contact with the slurry
Implementation Method 2
The dynamic viscosity and the density of the slurry increase approximately linearly with the GaAs content. The dynamic viscosity of the slurry for various GaAs contents for the Comparison is plotted against the shear rate in FIG. 12. The slurry in this case has a non-Newtonian behavior for each of the GaAs contents shown.
Data Source
AI summary
A wire saw (1; 100) for cutting a workpiece includes a device (21, 22, 24, 27) for setting, controlling and/or maintaining a predetermined or desired water content in at least part of the gaseous medium that contacts the slurry. With the wire saw according to the invention and the process carried out using this wire saw, it is possible to achieve consistently good surface properties of the resulting wafers over a prolonged period of use of a slurry.