Fixed-Abrasive Wire Grain Density Control for Wafer Slicing
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Solution Overview
Problem
The existing methods for slicing large diameter silicon ingots, such as those used in semiconductor manufacturing, face challenges with wafer shape accuracy and productivity due to meandering issues with fixed-abrasive-grain wires and the inefficiencies of loose-abrasive-grain methods.
Innovation Solution
A fixed-abrasive-grain wire with a core wire and abrasive grains, where the abrasive grain density is 1200 grains/mm2 or more and 2% or less of the distances between centroids are equal to or shorter than the average circle equivalent diameter, is used to control meandering and improve wafer shape accuracy, combined with a wire saw configuration and method for precise slicing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fixed-abrasive-grain wire with conventional abrasive grain density is used, then slicing time is reduced compared to loose-abrasive-grain method, but meandering occurs and wafer shape accuracy (TTV and warp) deteriorates
Solution Approach 1:
The patent changes the density parameter of abrasive grains on the wire surface to 1000 grains/mm² or more, and controls the distribution uniformity parameter (percentage of intercentroid distances ≤ average circle equivalent diameter) to 30% or less. These parameter optimizations enable the fixed-abrasive-grain wire to maintain high slicing speed while preventing meandering and ensuring wafer shape accuracy meets specifications.
2Manufacturing precision
If abrasive grain density is increased to prevent meandering, then wafer shape accuracy improves, but manufacturing complexity increases
Solution Approach 1:
The patent replaces complex mechanical distribution control mechanisms with a standardized electrolytic plating process that inherently achieves uniform abrasive grain distribution. By controlling plating conditions (electrolyte composition, current density, plating time), the desired grain density and uniformity are achieved without complex mechanical positioning systems.
3Manufacturing precision
If loose-abrasive-grain method is used, then wafer shape accuracy is maintained, but slicing time increases significantly for large diameter ingots
Solution Approach 1:
The patent introduces a fixed-abrasive-grain wire as an intermediary between the slicing mechanism and the workpiece. The wire serves as a carrier that delivers controlled abrasive grains directly to the cutting interface, eliminating the need for slurry delivery systems while maintaining precise wafer shape control and achieving high slicing speeds.
4Productivity
If conventional fixed-abrasive-grain wire is used, then slicing speed is improved, but costs increase due to abrasive grain consumption and waste disposal
Solution Approach 1:
The patent optimizes abrasive grain retention on the wire surface through controlled electrolytic plating, maximizing the utilization of each abrasive grain before it wears out or detaches. The uniform distribution pattern (≤30% intercentroid distance ratio) ensures even wear across all grains, extending wire life and reducing the frequency of wire replacement and abrasive grain replenishment.
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 approach significantly reduces slicing time and improves the shape accuracy of wafers, achieving high productivity and cost reduction by preventing agglomeration and ensuring uniform abrasive distribution.
Implementation Method 1
a fixed-abrasive-grain wire having diamond abrasive grains fixed to a core wire... the workpiece is sliced while supplying slurry containing suspended abrasive grains... the above manner can shorten the slicing time
Data Source
AI summary
The present invention is a fixed-abrasive-grain wire including a core wire and abrasive grains fixed on a surface of the core wire, wherein an abrasive grain density is 1200 grains/mm2 or more, where the abrasive grain density is the number of the abrasive grains per unit area on the surface of the core wire, and 2% or less of all distances between centroids of the abrasive grains are equal to or shorter than an average circle equivalent diameter of the whole abrasive grains. There can be provided a fixed-abrasive-grain wire, a wire saw, and a method for slicing a workpiece that can suppress meandering of the fixed-abrasive-grain wire during slicing a workpiece and improve TTV and warp of wafers sliced from the workpiece.