Shadow-gram Wafer Edge Inspection System
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Solution Overview
Problem
Current edge metrology techniques for stacked wafers are inaccurate and inefficient, struggling to effectively inspect complex edge profiles, leading to manufacturing errors, equipment damage, and downtime due to improper stacking and processing issues.
Innovation Solution
A system utilizing a light source and detector to acquire shadow-gram images of stacked wafers, with a controller analyzing these images to compare edge profiles against predetermined measurements, enabling real-time inspection and metrology across multiple points for accurate detection of centricity, glue excess, whiskers, and undercuts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual and offline edge profile measurement methods are used, then inspection can be performed, but the process is slow, time-consuming, and provides poor quality results
Solution Approach 1:
The patent replaces manual mechanical measurement methods with an automated optical inspection system that uses a light source and detector to capture shadow-gram images. This substitution enables real-time, high-speed inspection while maintaining or improving measurement accuracy through automated image analysis algorithms.
Solution Approach 2:
The patent creates an optical copy (shadow-gram image) of the edge profile instead of direct physical measurement. This optical replica allows for rapid capture and digital analysis, dramatically increasing inspection speed while preserving measurement precision through image processing techniques.
2Adaptability or versatility
If conventional inspection systems are used, then standard edge profiles can be detected, but complex edge profiles with undercuts, overhangs, or whiskers cannot be effectively analyzed
Solution Approach 1:
The patent uses shadow-gram imaging to capture edge profiles in a different dimensional representation than conventional methods. This shadow-gram dimension allows complex features like undercuts and overhangs to be visualized and measured accurately, extending the system's adaptability to various edge profile types while maintaining precision.
Solution Approach 2:
The patent changes the inspection parameter from direct optical reflection to shadow-gram projection. This parameter change enables the system to detect complex edge profiles that would be invisible or ambiguous in conventional reflection-based inspection, thereby improving both versatility and measurement precision for defective edges.
3Productivity
If stacked wafers with improper centricity are processed, then manufacturing can continue, but equipment damage or contamination can occur
Solution Approach 1:
The patent performs preliminary inspection of stacked wafer centricity and edge profiles before the wafers enter the manufacturing process. By detecting improper stacking, undercuts, or whiskers in advance, the system prevents these defects from causing equipment damage or contamination during subsequent processing steps, thereby protecting manufacturing continuity.
Solution Approach 2:
The patent implements a feedback mechanism where inspection results are immediately available to control the manufacturing process. When defective stacked wafers are detected, the system can provide feedback to halt processing or divert the defective wafers, preventing equipment damage while maintaining overall manufacturing productivity through real-time process control.
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
This solution provides accurate, real-time edge metrology and defect detection, enhancing manufacturing efficiency by identifying stacking errors and preventing equipment damage, while allowing for inline process control and feedback for improved wafer handling and processing.
Implementation Method 1
The light source is configured to direct collimated light at an edge of a stacked wafer. The detector is disposed opposite the light source and is configured to acquire a shadow-gram image of the edge of the stacked wafer.
Data Source
AI summary
Shadow-grams are used for edge inspection and metrology of a stacked wafer. The system includes a light source that directs collimated light at an edge of the stacked wafer, a detector opposite the light source, and a controller connected to the detector. The stacked wafer can rotate with respect to the light source. The controller analyzes a shadow-gram image of the edge of the stacked wafer. Measurements of a silhouette of the stacked wafer in the shadow-gram image are compared to predetermined measurements. Multiple shadow-gram images at different points along the edge of the stacked wafer can be aggregated and analyzed.