Wafer Topology Measurement System
The Solar Cell Wafer Topology Measurement System is a complete system for geometry, two-sided sawmarks and thickness measurements. Wafers are measured with low noise, high sensitivity, high repeatability and high resolution.
Unique shadow measurement techniques, cancelling the effects of the crystal pattern combined with Scorpion Vision Software® are the key elements of this world class system.
The combined sawmarks and thickness measurement system measures with a resolution of 1 micrometer.
The system is a standard instrument and can easily interface to any production line system.
Wafer sawmarks Sawmarks are measured using a patent pending and unique shadow measurement technique, cancelling the effects of the crystal pattern.
Advanced image processing algorithms work on the shadow images to identify sawmarks with high accuracy.
The operator can verify how the sawmarks develop over the wafer. Large sawmarks will often have a large gradient towards the edge of the wafer.
Wafer thickness The system measures both the mean thickness and the total thickness variation (TTV).
The wafer thickness is measured using an angled lighting and shadowing technique. The shadow position is measured simultaneously on both sides of the wafer.
The thickness is calculated from the shadow positions both at the wafer centre and 10 mm from the edges. Slightly warped wafers are handled. Wafer
geometry
The wafer dimension and corner shapes are measured.
The wafer dimension is determined based on these measurements:
The distance between parallel edges measured in two places
Length and angle of each edge
Corner measurements
The resolution is better than 0,01 mm on all length measurements.
Complete wafer
inspection system
The high precision, reliable and compact topology solution is built on the Scorpion Vision Software platform with 2D and 3D machine vision capabilities.
The interface to the automation and data collection system is highly flexible.
The system includes off-the-shelf world class hardware components such as area- and line scan camera technology.
Measurement Specification
Geometry
- Corner shape – length and angle of all
four corner grindings
- Wafer dimensions
- Length, width, diagonals, squareness
Thickness
- Thickness is measured on the middle of the wafer and 10 mm from the edges.
- 40 µm pixel size
- Resolution thickness and TTV: 1 µm
- Range: 50 to 250 µm
Sawmarks
- Sawmarks are measured with a profile resolution of 20, 40 or 70 µm. This means that narrow marks with a width of 100 µm are detected.
- One sided or two sided measurement
- The maximum sawmarks detected with a 1 mm window is measured from 4 - 100 µm with 1 µm repeatability.
More details in
pdf.
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