Wafer Edge

When particles in liquid or air hit the rough surface of the wafer, they may separate them and release silicon particles during processing, which can cause edge defects. Edge defects sometimes adversely affect semiconductor performance, so it is of great significance to evaluate the edge roughness of semiconductor wafers.

Alfa Chemistry guarantees the best quality of wafers. Our wafer edge analysis service can accurately identify defects such as etching residues and mechanical defects such as cracks or chips, and can eliminate defective wafers in the early stages of the experiment to avoid unnecessary experimental losses.

Types Of Wafer Edge

Two typical edge types are encountered in the semiconductor industry:

• Rounded or Blunt Shape
• Bullet or Beveled Shape

Figure 1 shows the two common wafer edge types and their edge geometries. Alfa Chemistry has a first-class technical team and advanced equipment, able to detect the typical edges. If you have other types of edges to be detected, please contact us for consultation.

Figure 1. Wafer shapes showing measurement regions

The five regions in the figure are:
A - The crown or apex;
B - The front side bevel or rounded region;
C - The transition area between the polished side and the edge;
D - The back side bevel or rounded region.
E - The transition area between the back side and the edge.

Measurement Methods & Instrument Platforms

Edge roughness control has become an indispensable problem in semiconductor wafer production. Alfa Chemistry uses non-contact measurement techniques for wafer edge analysis, which is very beneficial because they do not contaminate samples and generally do not require extensive preparation.

The Chapman Instruments MP2000 Plus system adopted by Alfa Chemistry complies with the SEMI Standards Committee and can be used to report the contour and roughness information of the wafer edge.

• All the measurements we obtained were made with the MP2000 Plus non-contact surface profiler equipped with a 50X objective lens and Nomarski II prism.
• The spatial resolution of this optical component is 0.7 µm and the maximum surface tilt is 16.7 degrees.

Testing Standard

• ASTM F1810-1997 Standard Test Method for Statistical Analysis of Silicon Wafer Erosion or Surface Defects
• GB/T 30860-2014 Test Method for Surface Roughness and Cutting Line Marks of Silicon Wafers for Solar Cells
• GB/T 6620-2009 Non-contact Test Method for Wafer Warpage
• GB/T 19922-2005 Non-contact Standard Test Method for Local Flatness of Silicon Wafer