Wire Saw Slice Separation Using Thermal and Axial Shape Correction
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Solution Overview
Problem
Conventional wire saw methods for separating slices, such as lap slicing and grind slicing, face limitations in achieving high flatness and plane parallelism, particularly in the semiconductor industry, due to inherent limitations in controlling the relative positions of the wire frame and workpiece during cutting processes.
Innovation Solution
A method that involves controlling the temperature of the workpiece and the wire guide rollers using a cooling medium and simultaneous axial displacement of the movable bearing, with temperature profiles and correction profiles to minimize shape deviations, combining wire guide temperature control and ingot positioning control to achieve precise alignment and displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wire saw methods (lap slicing or grind slicing) are used, then the cutting process can be performed, but the flatness and plane parallelism of separated discs deteriorate due to inability to control relative positions of wire frame and workpiece
Solution Approach 1:
The patent applies parameter changes by controlling the temperature of the wire guide roller bearings to induce thermal expansion or contraction, which adjusts the axial position of the wire frame relative to the workpiece. This thermal parameter control enables precise adjustment of cutting depth and maintains flatness and plane parallelism without requiring complex mechanical positioning systems.
Solution Approach 2:
The patent replaces complex mechanical positioning systems with a thermal control system. Instead of using intricate mechanical devices to adjust the relative position of the wire frame and workpiece, the invention uses temperature control of the bearings to achieve the same positioning effect through thermal expansion and contraction, thereby reducing mechanical complexity while improving precision.
2Manufacturing precision
If temperature control of wire guide roller is applied, then the position of reference surface can be balanced, but the control bandwidth is limited and effect is insufficient for high-frequency shape deviations
Solution Approach 1:
The patent implements dynamics by combining two control systems with different response characteristics: a slow thermal control system for low-frequency shape deviations and a fast mechanical positioning system for high-frequency deviations. This dynamic combination allows the system to handle both low-frequency thermal expansion effects and high-frequency positioning errors, achieving comprehensive shape control across different frequency ranges.
3Manufacturing precision
If greater displacement amplitudes are required to correct shape deviations, then the control range increases, but the existing bearing arrangement limits the achievable displacement
Solution Approach 1:
The patent directly applies thermal expansion by heating or cooling the wire guide roller bearings to change their dimensions. This thermal expansion/contraction mechanism provides an additional displacement range beyond what is achievable with mechanical adjustment alone, enabling greater correction amplitudes for shape deviations while maintaining the physical constraints of the bearing arrangement.
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
This method significantly improves the flatness and plane parallelism of separated discs by allowing greater displacement amplitudes and control bandwidths, effectively reducing shape deviations and achieving discs with shapes closer to the target profile, even in high-frequency and low-frequency deviations.
Implementation Method 1
controlling the temperature of the workpiece and the wire guide rollers using a cooling medium
Implementation Method 2
minimize shape deviations... temperature profiles and correction profiles to minimize shape deviations
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method for cutting a plurality of discs from workpieces (4) using a wire saw during a sequence of cutting operations subdivided into initial cuts and subsequent cuts, wherein the wire saw comprises a wire frame (2) made of moving wire segments of a saw wire (3) and a positioning device (12), and the wire frame (2) is clamped in a plane between two wire guide rollers (1), each of the two wire guide rollers (1) being mounted between a fixed bearing (5) and a floating bearing (6). The method comprises, during each of the cutting operations, feeding the respective workpiece (4) through the wire frame (2) by means of the positioning device (12) along a feeding direction perpendicular to a workpiece axis and perpendicular to the plane of the wire frame (2) in the presence of a working fluid and hard materials that act abrasively on the workpiece (4).characterized by the following during each of the cutting operations: feeding the workpiece (4) through the wire screen (2) while regulating the temperature of the workpiece (4) by wetting the workpiece (4) with a cooling medium; during each of the cutting operations, feeding the workpiece (4) through the wire screen (2) while simultaneously axially displacing the floating bearings (6) by tempering the fixed bearings (5) with a cooling fluid according to a first temperature profile, which specifies the temperature of the cooling fluid as a function of a cutting depth and correlates with a first correction profile, which specifies the displacement of the floating bearings (6) as a function of the cutting depth; and feeding the workpiece (4) through the wire screen (2) while simultaneously displacing the workpiece (4) along the workpiece axis by means of an adjusting element (15) according to a second correction profile, which specifies the displacement of the workpiece (4).wherein the first and second correction profiles are directed against a shape deviation; and the determination of the shape deviation during each of the cutting operations and/or before each of the cutting operations.