Wire Saw Speed Regulation for Uniform Wear
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Solution Overview
Problem
Existing wire saw methods experience inhomogeneous wear of the sawing wire due to varying incision lengths, leading to increased total thickness variance and undesirable wire wear patterns, particularly when slicing large semiconductor wafers.
Innovation Solution
A method that regulates the effective speed of the sawing wire as a function of the forward feed rate and workpiece cross section, ensuring uniform wire wear by varying the table forward feed rate and optimizing the wire speed profiles for forward and backward movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the table forward feed is kept constant during the sawing process, then the sawing wire wear is reduced initially, but the total thickness variance of the semiconductor wafers is increased in the region of the greatest incision lengths
Solution Approach 1:
The patent applies dynamics by making the table forward feed variable rather than constant. The feed rate is dynamically adjusted as a function of the incision length, transitioning from a static parameter to a dynamic one that adapts during the cutting process. This resolves the contradiction by allowing the system to optimize both wire wear and wafer thickness precision through continuous parameter adjustment.
Solution Approach 2:
The patent changes the parameter of table forward feed from a constant value to a variable value that depends on the incision length. By modifying this key parameter dynamically during the cutting process, the system achieves uniform wire wear while maintaining consistent wafer thickness, thereby resolving the technical contradiction between wire wear uniformity and manufacturing precision.
2Reliability
If the table forward feed is varied as a function of the incision length to reduce wire wear, then wire wear becomes more uniform, but the total thickness variance of the wafers increases
Solution Approach 1:
The patent changes the parameter of table forward feed from a constant value to a variable value that depends on the incision length. By modifying this key parameter dynamically during the cutting process, the system achieves uniform wire wear while maintaining consistent wafer thickness, thereby resolving the technical contradiction between wire wear uniformity and manufacturing precision.
Solution Approach 2:
The patent implements a feedback mechanism where the table forward feed rate is continuously adjusted based on the current incision length. This closed-loop control ensures that the feed rate adapts to the changing cutting conditions, achieving both uniform wire wear and consistent wafer thickness by responding to real-time process parameters.
3Productivity
If the sawing wire speed is increased to maintain productivity with variable feed rates, then the cutting efficiency improves, but the wire wear becomes inhomogeneous
Solution Approach 1:
The patent applies dynamics by making the sawing wire speed variable rather than constant. The wire speed is dynamically adjusted in coordination with the table forward feed rate, allowing the system to maintain high productivity while ensuring uniform wire wear through adaptive parameter control during the cutting process.
Solution Approach 2:
The patent changes the parameter of sawing wire speed from a constant value to a variable value that depends on the forward feed rate and incision length. By modifying this key parameter dynamically, the system achieves both high cutting efficiency and uniform wire wear, resolving the contradiction between productivity and reliability.
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
Achieves more homogeneous wire wear, preventing contamination of the slurry and allowing multiple uses of the sawing wire without introducing copper into the slurry, while maintaining consistent wafer quality and reducing wire wear-related issues.
Implementation Method 1
The sawing wire may be covered with a cutting layer. When using wire saws having a sawing wire without firmly bound cutting abrasive, cutting abrasive in the form of a suspension (slurry) is supplied during the slicing process.
Data Source
AI summary
A multiplicity of wafers are sliced from a workpiece which has a longitudinal axis and a cross section, the workpiece fastened on a table being fed by a relative movement directed perpendicularly to the longitudinal axis of the workpiece between the table and the wire gang of a wire saw, with a variable forward feed rate through the wire gang formed by a sawing wire moved with an effective speed, the effective speed of the sawing wire being regulated as a function of the forward feed rate and the workpiece cross section so as to result in uniform wear of the sawing wire.