Wire Saw Slice Correction for Flatness and Parallelism
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Solution Overview
Problem
Existing methods for cutting slices from workpieces using wire saws fail to meet the increasing demands for flatness and plane parallelism, especially in the semiconductor industry, despite existing measures to improve slice quality.
Innovation Solution
A method involving a wire saw with a wire array tensioned between fixed and floating bearings, utilizing temperature control of fixed bearings (WGTC) and axial movement of the workpiece (IPC) to correct shape deviations during cut-off operations, combined with ingot cooling (IC) to manage thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wire saw methods are used with fixed and floating bearings, then the basic cutting function is maintained, but the flatness and plane parallelism of slices deteriorate due to shape deviations caused by thermal expansion and mechanical instability
Solution Approach 1:
The patent applies dynamics by making the previously fixed bearing movable through piezoelectric actuators. The fixed bearing is transformed into a dynamically adjustable component that can change its position in real-time during the cutting process, allowing continuous compensation for thermal expansion and shape deviations, thereby improving slice flatness and plane parallelism
Solution Approach 2:
The patent implements feedback control by using sensors to continuously monitor the shape of slices during cutting and feeding this information back to the piezoelectric actuators. This closed-loop system enables real-time adjustment of the bearing position and wire array configuration to counteract detected shape deviations, directly addressing the flatness and parallelism requirements
Solution Approach 3:
The patent changes physical parameters by controlling the temperature of the workpiece and wire array through cooling systems. By maintaining optimal temperature parameters, thermal expansion is minimized, which directly reduces shape deviations and improves the geometric precision of slices
2Manufacturing precision
If the position of wire guide roller is adjusted to compensate for thermal expansion, then flatness improves, but the complexity of the control system increases
Solution Approach 1:
The patent applies self-service by enabling the system to automatically monitor and correct its own deviations. The sensors detect shape deviations and the piezoelectric actuators automatically adjust the bearing position without external intervention, making the complex control system self-regulating and reducing the need for manual adjustment mechanisms
Solution Approach 2:
The patent replaces complex mechanical adjustment mechanisms with piezoelectric actuators that provide precise, electrically controlled position changes. This substitution reduces mechanical complexity while enabling finer control resolution and faster response times for compensating thermal expansion effects
3Manufacturing precision
If multiple correction measures are implemented simultaneously, then shape accuracy improves, but the difficulty of detecting and measuring deviations increases
Solution Approach 1:
The patent applies segmentation by dividing the correction process into distinct functional modules: temperature control, bearing position adjustment, and wire array configuration. Each module can be independently monitored and adjusted, simplifying the measurement and control of shape deviations despite multiple simultaneous corrections
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 slices with improved shape accuracy by minimizing shape deviations through coordinated control of temperature and axial movement, enabling higher-frequency and lower-frequency corrections, thus enhancing the flatness and parallelism of slices.
Implementation Method 1
controlling a temperature of the workpiece by wetting the workpiece with a cooling medium
Implementation Method 2
a thermal length increase or length decrease in the wire guide roller is brought about by adjusting the temperature of the wire guide roller interior
Data Source
AI summary
A method cuts slices from workpieces using a wire saw with a wire array tensioned in a plane between two wire guide rollers supported between fixed and floating bearings. A workpiece is fed through the wire array perpendicular to a workpiece axis and the wire array plane. The workpiece is fed through the wire array while controlling a temperature of the workpiece with a cooling medium, with simultaneous axial movement of the floating bearings by adjusting a temperature of the fixed bearings in dependence on a depth of cut and in correlation with a first correction profile, and while simultaneously moving the workpiece along the workpiece axis in accordance with a specification of a second correction profile, which specifies a travel of the workpiece. The first correction profile and the second correction profile being opposed to a shape deviation.