Wi8i G2's New Inspection Algorithm for Precise Defect Detection

The Wi8i G2 Wafer Vision Inspection Handler is designed to support 2D surface defect inspections and metrology for a variety of wafer forms, including raw wafer, hoop ring wafer, and framed wafer, ranging from 100 mm (4") to 300 mm (12").

Posted on September 2, 2021

The Wi8i G2 Wafer Vision Inspection Handler is designed to support 2D surface defect inspections and metrology for a variety of wafer forms, including raw wafer, hoop ring wafer, and framed wafer, ranging from 100 mm (4") to 300 mm (12"). The wafer vision inspection handler has a variety of handling mechanisms that can displace the conventional manual visual inspection while offering reliable, repeatable, and reproducible inspection results.

Wi8i G2 has now been upgraded with its system, Smart Thresholding, with the new defect detection algorithm. With this new algorithm, the Wi8i G2 is now equipped with precise defect identification capabilities that are capable of delivering a high-quality inspection result.

The conventional defect detection algorithm back then was constrained by the defect region condition, which results in random defects that are impossible to detect, primarily due to two fundamental limitations:

  1. When the defect is located in a low-contrast region.
  2. When the defect is located in a low-sensitivity region.

If you look at sample 1 below, you'll notice that the defects are hard to spot in the low-contrast grey area.

Sample 1

The majority of defect detection algorithms search for abnormalities on the die surface using grayscale differentiation. When the low contrast/ sensitivity inspection region restricts the grayscale differentiation employed in defect detection which causes an increase in underkill and overkill, it becomes extremely challenging for the system to produce a consistent and accurate inspection result.

Another example (Sample 2) illustrates an underkill result and demonstrates how the defect is detected under the conventional defect detection algorithm.

Sample 2

On the other hand, the overkill result in Samples 3 and 4 illustrates how the defect would appear to be under the same algorithm.

Sample 3
Sample 4

Wafer fabrication variance is taken into consideration by the new Smart Thresholding algorithm, which can detect anomalies in low contrast and low sensitivity regions. Utilising a simple and customizable recipe configuration, users are able to obtain reliable results using the Smart Thresholding algorithm. The new algorithm significantly lowers inspection error, enhancing user confidence in the product's quality.

In addition to the new algorithm that provides a comprehensive one-stop solution for wafer inspection, Wi8i G2 also supports hoop ring inspection, back chipping inspection, kerf inspection, skeleton wafer inspection, etc. With these inspection abilities, Wi8i G2 is a customer-oriented, flexible and cost-effective solution to handle the semiconductor's most demanding applications, including RF, MEMS, CIS, LED, and Memory as well as numerous wafer fabrication process steps.

If you are interested in the ViTrox Wi8i G2 wafer vision handler, reach out to our sales expert Ms. Kong Poh Mei!