Flatness・Light Point Defects / Categories of Off-Orientation |
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Flatness |
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Definitions of Flatness |
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Total Thickness Variation：
The difference between the highest and the lowest elevation of the top surface of a clamped wafer.
The back surface referenced. |
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Total Indicated Reading：
The difference between the highest point above and the lowest point below the front surface referenced focal plane of a clamped wafer.
3 points on the front surface generally used. |
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Local Thickness Variation:
The difference between the highest point and the lowest point within a site of the top surface of a clamped wafer.
The back surface referenced. |
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Percent LTV：
Percentage of sites on a wafer within the specified LTV value. |
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The difference between the highest point above and the lowest point below the front surface referenced focal plane of an
unclamped wafer.
A least square fit on the front surface generally used. |
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Light Point Defects |
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Clockwise (EJ) / Counter Clockwise (US) |
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Planar Representation of Cubic
Form |
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Example of off－orientation |
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To Catalog List (GaAs
Sub) |
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