Semiconductor Die Tilt Inspection Using Multi-Angle Outline Imaging
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Solution Overview
Problem
Existing inspection methods for semiconductor die tilt, such as three-dimensional illumination and White Light Scanning Interferometry, struggle to accurately determine the tilt angle when the die is tilted at angles greater than a certain threshold due to total reflection or inaccurate shape derivation from a reflector surface.
Innovation Solution
An apparatus and method using multiple light sources (illumination and pattern) and cameras to capture images from different angles, determining outlines and virtual planes to measure the tilt angle accurately, even when the die is tilted and made of a reflector material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three-dimensional illumination light is used to inspect the semiconductor die, then the tilt angle can be measured, but the image cannot be captured well due to total reflection on the reflective upper surface
Solution Approach 1:
The patent introduces a reference object with a non-reflective surface as an intermediary element. This reference object serves as a mediator between the light source and the reflective semiconductor die, providing a contrasting background that enables image capture despite the total reflection from the die's surface. The reference object's surface allows light to be absorbed or scattered in a way that creates visible contrast for imaging.
2Measurement precision
If White Light Scanning Interferometry is used for tilt inspection, then the tilt angle can be measured, but the method fails when the die is tilted at angles greater than 1.2 degrees
Solution Approach 1:
The patent transitions from the interferometric measurement approach (which operates in a specific angular range) to a multi-dimensional imaging approach using multiple cameras positioned at different angles. By capturing images from multiple dimensions and perspectives, the system can determine tilt angles beyond the 1.2-degree limitation of White Light Scanning Interferometry, effectively extending the measurement range through dimensional diversification.
3Measurement precision
If two-dimensional area inspection is used to measure tilt through parallelogram shape, then the tilt angle can be derived, but accurate shape cannot be acquired due to total reflection
Solution Approach 1:
The patent applies local quality by introducing a reference object with specific surface properties (non-reflective) in the local measurement area. This reference object provides a localized region where light interaction produces visible contrast, enabling accurate shape and outline detection. The combination of the semiconductor die and reference object creates a composite image where the reference object's known geometry serves as a calibration reference for accurate tilt 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 precise measurement of tilt angles and generation of accurate virtual three-dimensional models for semiconductor dies, overcoming challenges of total reflection and inaccurate shape derivation.
Implementation Method 1
one or more cameras configured to capture one or more illumination images generated by the illumination light reflected from the object
Data Source
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AI summary
The present disclosure presents a device. The device according to the present disclosure comprises: at least one first light source for emitting illumination light at an object positioned on a reference surface; one or more cameras for capturing one or more lighting images generated when the illumination light has been reflected by the object; and one or more processors, wherein the processors can determine one or more contour lines that indicate the edges of the object on the one or more lighting images, determine, on the basis of the one or more contour lines, a height value possessed by the edge of an upper surface of the object with respect to the reference surface, and determine a first angle between the upper surface of the object and the reference surface on the basis of the height value.