Wafer Backside Defect Detection via Oblique Light Scattering
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Solution Overview
Problem
Current methods for detecting wafer backside defects are inadequate as they cannot analyze the height distribution of defects, which is crucial for determining the source and severity of defects, leading to potential issues in photolithography processes.
Innovation Solution
A method involving the creation of a signal database with 3D information from emitted and scattered light signals, using an oblique incident light source to scan wafers and compare data to form a 3D distribution map of defects, allowing for the analysis of defect height or depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical scanning is used to form a photo for defect detection, then the defect distribution map can be generated, but the height distribution of defects cannot be analyzed
Solution Approach 1:
The patent transitions from 2D optical scanning to 3D defect detection by introducing oblique incident light at multiple angles. This dimensional change enables the system to capture height and depth information of defects, transforming the detection capability from planar distribution mapping to three-dimensional characterization including height distribution analysis
Solution Approach 2:
The patent changes the detection parameters by using oblique incident light at different angles instead of conventional normal incidence. This parameter change in light incidence angle enables the system to extract height and depth information from defects, converting the detection from qualitative 2D mapping to quantitative 3D measurement
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
Enables the detection of wafer backside defects in 3D, facilitating timely identification of defect sources and reducing troubleshooting time, thereby improving product yield and process efficiency.
Implementation Method 1
signal data being data formed by transforming emitted and scattered light signals collected after an oblique incident light source is irradiated to the corresponding defect
Implementation Method 2
collecting reflected and scattered light signals corresponding to the each of the test patterns
Data Source
AI summary
The present disclosure discloses a method for detecting a wafer backside defect, comprising: Step 1, providing a signal database comprising signal data corresponding to various different defects, the defects comprising convex defects and concave defects, the signal data reflecting 3D information of the corresponding defect; Step 2, performing backside scanning on a tested wafer by using oblique incident light, and collecting corresponding emitted and scattered light data; and Step 3, comparing the collected emitted and scattered light data with the signal data, and fitting a defect 3D distribution map of the backside of the tested wafer. The present disclosure can test the height or depth of a wafer backside defect and form a 3D distribution map of the wafer backside defect, which is beneficial for analyzing the source of the wafer backside defect and processing it in time, reducing the troubleshooting time and improving the product yield.