Multi Wire Saw Gang Length Optimization with Spacer Elements
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Solution Overview
Problem
Existing methods for slicing cylindrical semiconductor workpieces into wafers using multi wire saws face challenges such as suboptimal utilization of gang length, wafer damage during separation, and difficulty in inserting separating plates, leading to reduced economic viability and wafer quality issues.
Innovation Solution
Selecting workpieces of varying lengths to maximize gang length utilization and using spacer elements on the wafer carrier to prevent edge damage and lateral tilting, while employing a multi wire saw with spacer pieces to separate and support wafer stacks during the slicing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple workpieces are simultaneously clamped and sliced in a multi wire saw, then throughput is increased, but wafer stacks become unstable and edges fracture
Solution Approach 1:
The patent introduces separating plates as intermediary elements inserted between stacks of wafers. These plates provide lateral support and stability to the wafer stacks during and after the slicing process, preventing edge fracture while allowing multiple workpieces to be processed simultaneously. The separating plates act as mediators that maintain structural integrity without interfering with the high-throughput simultaneous slicing operation.
2Loss of information
If separating plates are inserted between wafer stacks to prevent mixing, then wafer identification is improved, but insertion difficulty increases and wafer damage risk rises
Solution Approach 1:
The patent applies preliminary action by inserting separating plates into grooves that are pre-formed in the mounting plate during the slicing process. This preliminary preparation of insertion pathways eliminates the difficulty of manually positioning separating plates between unstable wafer stacks. The plates are guided into place through the grooves, ensuring proper positioning without requiring complex manual manipulation or risking wafer damage.
3Adaptability or versatility
If workpieces of different lengths are processed, then customer-specific requirements are met, but gang length utilization becomes suboptimal
Solution Approach 1:
The patent applies local quality by providing individual spacing adjustment capability for each workpiece position on the mounting plate. Each workpiece can be positioned with optimal spacing specific to its length and processing requirements, rather than using a uniform spacing for all positions. This localized optimization allows the system to accommodate workpieces of varying lengths while maximizing the utilization of the available gang length, thereby maintaining both adaptability and productivity.
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 optimizes the utilization of multi wire saw capacity, reduces wafer damage, and ensures efficient separation and processing of wafers with improved geometric quality and productivity.
Implementation Method 1
The hot water dissolves the cement bond between the wafers and the sawing bars, so that the detached wafers fall into a wafer carrier placed at the bottom of the basin.
Data Source
AI summary
Slicing multiple cylindrical workpieces into wafers by a multi wire saw with a gang length LG, is performed by:a) selecting a number n≧2 of workpieces from a stock of workpieces with different lengths, satisfying the inequalityLG≥(n-1)·Amin+∑i=1nL1(1)and making right-hand side of the inequality as large as possible, where Li with i=1 . . . n are for the lengths of the workpieces and Amin is a predefined minimum spacing,b) fixing the n workpieces successively in the longitudinal direction on a mounting plate while maintaining a spacing A≧Amin therebetween such that the relationshipLG≥(n-1)·A+∑i=1nLi(2)is satisfied,c) clamping mounting plates workpieces in a multi wire saw, andd) slicing the n workpieces perpendicularly to their longitudinal axis by means of the multi wire saw. Preferably, the wafer stacks are separated from one another by separating pieces after slicing, and at the same time are laterally supported.