Wire Guide Roller Thermal Compensation for Wafer Flatness
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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, where demands are increasingly stringent, despite existing measures to control temperature and reduce warp and shape deviations.
Innovation Solution
A method that involves tempering the chambers of wire guide rollers with a first coolant following a temperature profile correlated with cutting depth to adjust jacket length and simultaneously displacing the floating bearings of wire guide rollers with a second coolant, both processes aimed at counteracting shape deviations, combined with infeed adjustments of the workpiece to minimize shape deviations through precise temperature control and displacement profiles.
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 slices deteriorate due to shape deviations and warp
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the temperature of wire guide rollers during the cutting process. By changing the temperature parameter of the wire guide rollers, the patent compensates for shape deviations and improves the flatness and plane parallelism of separated slices, directly addressing the technical contradiction between achieving precise cutting and avoiding shape deviations
Solution Approach 2:
The patent replaces purely mechanical positioning systems with a thermally-controlled system. Instead of using only mechanical adjustments to maintain wire gate position, the patent introduces thermal control of wire guide rollers to actively compensate for shape deviations, substituting mechanical rigidity with thermal adaptability to improve manufacturing precision
2Stability of the object's composition
If temperature control measures are applied to limit warp, then the shape stability improves, but the device complexity increases due to additional cooling systems
Solution Approach 1:
The patent applies universality by integrating the cooling system into the existing wire guide roller structure. The wire guide rollers serve dual functions: guiding the saw wire and providing thermal control to compensate for shape deviations. This multi-functionality reduces device complexity while maintaining shape stability, as the same component performs both mechanical and thermal control functions
Solution Approach 2:
The patent merges the cooling system with the wire guide roller structure by providing cooling channels directly within the rollers. This integration combines the mechanical guidance function and thermal control function into a single unified system, reducing overall device complexity while achieving shape stability through active temperature management
3Device complexity
If the wire guide roller structure is simplified with fixed bearings, then the device complexity reduces, but the manufacturing precision deteriorates due to inability to compensate for thermal expansion
Solution Approach 1:
The patent applies dynamics by using floating bearings instead of fixed bearings for the wire guide rollers. The floating bearing design allows the rollers to move dynamically in response to thermal expansion and contraction, enabling the system to adapt to temperature changes while maintaining cutting precision. This dynamic adjustment capability resolves the contradiction between simple structure and high precision
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 slices by dynamically adjusting the wire guide rollers and workpiece position in real-time, enhancing the precision and accuracy of the cutting process, particularly for large semiconductor wafers, by compensating for shape deviations and reducing wear-related issues.
Implementation Method 1
the jacket is typically attached to the core of the respective wire guide roller of the wire creel in such a way that it is free to expand or contract axially at both ends as the temperature changes
Implementation Method 2
US 2012/0 240 915 A1 describes a method that provides for the independent cooling of the wire guide rollers and their fixed bearings in order to reduce relative axial movement of the wire sections and the workpiece caused by temperature changes
Implementation Method 3
During cut-off lapping, the working space formed between the wire surface and the workpiece is supplied with working liquid in the form of a slurry of hard materials in a liquid carrier medium. During cut-off lapping, the material is removed by means of a three-body interaction consisting of tool carrier (saw wire), tool (abrasive) and workpiece
Implementation Method 4
During cut-off grinding, saw wire is used with hard materials firmly embedded in its surface, and a working fluid is fed in that itself contains no abrasive materials and acts as a cooling lubricant
Data Source
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AI summary
Method for separating a plurality of discs from workpieces (4) by means of a wire saw during a sequence of separation operations subdivided into initial cuts and subsequent cuts, wherein the wire saw comprises a wire frame (2) of moving wire sections of a saw wire (3) and an adjusting device (12), and the wire frame (2) is clamped in a plane between two wire guide rollers (1), wherein each of the two wire guide rollers (1) is mounted between a fixed bearing (5) and a floating bearing (6) and comprises at least one chamber (18) and a shell (8) which encloses a core (17) of the wire guide roller (1) and which is structured with guide grooves for the wire sections,The method comprises, during each of the cutting operations, feeding the respective workpiece (4) through the wire screen (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 screen (2) in the presence of a working fluid and hard materials that act abrasively on the workpiece (4), characterized by, during each of the cutting operations, feeding the workpiece (4) through the wire screen (2) while simultaneously changing the length of the sleeves (8) of the two wire guide rollers (1) by tempering the chambers (18) of the wire guide rollers (1) with a first cooling fluid according to the specification of a first temperature profile, which specifies the temperature of the first cooling fluid as a function of a cutting depth and which correlates with a first correction profile.which specifies the change in the length of the sleeves (8) as a function of the cutting depth; and while simultaneously axially displacing the floating bearings (6) of the two wire guide rollers (1) by tempering the fixed bearings (5) of the wire guide rollers (1) with a second cooling fluid according to a second temperature profile, which specifies the temperature of the second cooling fluid as a function of the cutting depth and correlates with a second correction profile, which specifies the displacement of the floating bearings (6) as a function of the cutting depth, wherein the first and the second correction profiles are directed against a form deviation; and determining the form deviation before each of the cutting operations.