Wafer Beveled-Edge Trimming With Non-Intersecting Blade Axes
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Solution Overview
Problem
The existing edge trimming processes for semiconductor wafers with beveled edges often result in abrasive grain marks and chippings, leading to cracks and reduced quality of device chips during the grinding and division processes.
Innovation Solution
A method of processing a workpiece with a beveled edge that involves an edge trimming process using an annular cutting blade, where the cutting blade rotates about its central axis, and the chuck table rotates about a perpendicular axis, ensuring that the table rotation axis and blade rotation axis do not intersect, thereby reducing abrasive grain marks and chippings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cutting blade cuts into the wafer while the wafer is being rotated with the table rotation axis and blade rotation axis intersecting, then the edge trimming process can be performed, but abrasive grain marks and chippings are generated on the surface
Solution Approach 1:
The patent applies asymmetry by making the rotation axes non-intersecting, specifically positioning the blade rotation axis offset from the table rotation axis. This asymmetric configuration changes the cutting trajectory so that the cutting direction is not always parallel to the surface, preventing abrasive grain marks while maintaining effective edge trimming.
Solution Approach 2:
The patent introduces a spatial dimension change by making the blade rotation axis and table rotation axis non-intersecting in three-dimensional space. This dimensional adjustment creates a complex cutting path that prevents the formation of surface marks while effectively removing material for edge trimming.
2Ease of manufacture
If the cutting blade cuts into the beveled edge to remove material, then the beveled edge is removed, but knife-edge shape is formed which is liable to chip
Solution Approach 1:
The non-intersecting rotation axes create an asymmetric cutting pattern that removes material more uniformly, preventing the formation of concentrated stress points that lead to knife-edge shapes. This asymmetric motion distributes the cutting action to maintain edge strength.
Solution Approach 2:
The patent employs dynamic cutting motion where both the wafer and blade rotate simultaneously with non-intersecting axes, creating a complex, continuously changing cutting trajectory. This dynamic motion prevents static stress concentration and produces a more uniform material removal pattern that maintains edge integrity.
3Productivity
If the wafer is ground after edge trimming, then thickness is reduced, but cracks are brought about from abrasive grain marks and chippings
Solution Approach 1:
The patent applies preliminary action by optimizing the edge trimming process before grinding to prevent the formation of abrasive grain marks and chippings. By using non-intersecting rotation axes during trimming, the surface is prepared in advance to resist crack formation during subsequent grinding, ensuring wafer integrity throughout the manufacturing process.
4Ease of manufacture
If the cutting blade rotates about central axis and wafer rotates on chuck table, then edge trimming is achieved, but terrace surface and wall surface are formed with abrasive grain marks
Solution Approach 1:
The patent uses asymmetry by offsetting the blade rotation axis from the table rotation axis, creating a non-symmetric cutting path. This asymmetric motion prevents the formation of regular terrace surfaces with aligned abrasive marks, instead producing a more uniform surface morphology without concentrated grain marks.
Solution Approach 2:
The non-intersecting rotation axes create a curved, complex cutting trajectory rather than a linear or planar path. This curvilinear motion pattern distributes cutting action across the surface in a way that prevents the formation of flat terrace surfaces with visible abrasive grain marks, resulting in a smoother surface morphology.
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 improves the surface roughness of the workpiece by polishing off abrasive grain marks, reduces the likelihood of cracks and chippings, and enhances the quality and yield of device chips, increasing the efficiency of the chip fabrication process.
Implementation Method 1
forcing a cutting edge portion of an annular cutting blade to cut into the beveled edge of the workpiece while the cutting blade is rotating about a blade rotation axis
Implementation Method 2
the chuck table to make at least one revolution about the table rotation axis, thereby cutting into the beveled edge with the cutting blade along an entire outer circumference of the workpiece
Data Source
AI summary
A method of processing a workpiece having a beveled edge on its outer circumferential portion to cut off a part of the outer circumferential portion includes placing the workpiece on a holding surface of a chuck table that is rotatable about a table rotation axis, forcing a cutting edge portion of an annular cutting blade to cut into the beveled edge while the cutting blade is rotating about a blade rotation axis, and rotating the chuck table about the table rotation axis, thereby cutting into the beveled edge with the cutting blade to cut off a part of the workpiece. While the cutting blade is cutting into the beveled edge, the table rotation axis and the blade rotation axis do not intersect with each other.