Wire Saw Roller Thermal Control for Uniform Wafer Bow
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Solution Overview
Problem
Conventional wire saw methods for slicing ingots result in irregular Bow (Sori) directions across wafers, necessitating cumbersome pre-polishing measurements and wafer reorientation for epitaxial growth, which complicates the manufacturing process and reduces efficiency.
Innovation Solution
A slicing method where the wire saw's grooved rollers are pre-tested to establish a slurry supply temperature profile that aligns the axial displacement, ensuring all wafers are sliced with uniform Bow directions, eliminating the need for pre-measurement and reorientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional wire saw slicing is used, then wafers can be produced, but Bow directions become irregular requiring additional measurement and reorientation steps
Solution Approach 1:
The grooved rollers are pre-heated before slicing to expand them thermally, which compensates for slicing-induced compression and maintains uniform Bow directions in all wafers. This preliminary thermal preparation eliminates the need for post-slicing measurement and reorientation steps, directly resolving the contradiction between productivity and process complexity.
Solution Approach 2:
The temperature of the grooved rollers is changed as a control parameter to alter their dimensional state. By heating the rollers to a specific temperature range, their expansion compensates for compression during slicing, ensuring uniform Bow directions without requiring additional process steps for measurement and reorientation.
2Loss of time
If conventional slicing without temperature control is used, then slicing can be performed quickly, but additional post-processing steps are required
Solution Approach 1:
Temperature control of the slurry and grooved rollers is applied before and during slicing to prevent Bow direction irregularities. This preliminary thermal preparation eliminates the need for post-slicing measurement and reorientation, converting a time-consuming post-processing requirement into a controlled processing parameter.
Solution Approach 2:
The mechanical post-processing steps of measurement and reorientation are replaced by thermal control during slicing. By controlling the temperature of the grooved rollers and slurry, the system automatically produces wafers with uniform Bow directions, substituting complex mechanical operations with simpler thermal management.
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 enhances reproducibility and efficiency by uniformly aligning Bow directions in sliced wafers, simplifying the epitaxial growth process and reducing operational complexity.
Implementation Method 1
a test of slicing the ingot while supplying the slurry for slicing to the grooved rollers and controlling a supply temperature of the slurry is previously conducted to examine a relationship between an axial displacement of the grooved rollers and a supply temperature of the slurry
Data Source
AI summary
A wafer slicing method includes winding a wire around rollers and pressing the wire against an ingot while supplying slurry to the rollers. A previously conducted experiment provides a supply temperature profile of the slurry during the slicing process and the relationship to the axial displacement of the rollers. This relationship is used to implement slurry delivery during the slicing process. The resultant wafers are bowed in a uniform direction. This slicing method provides excellent reproducibility in addition to producing wafers that are bowed in a uniform direction.