Wafer Notch Shape Measurement With Controlled Light Incidence
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Solution Overview
Problem
Conventional methods for measuring the three-dimensional shape of semiconductor wafer notch portions are inaccurate due to blurring from wafer alignment, crystal orientation, and light diffraction, limiting the ability to accurately measure complex shapes.
Innovation Solution
A shape measurement device that includes an imaging system, stage system, and control device, which adjusts the attitude of the measurement object to acquire multiple surface images and generate a three-dimensional shape model using imaging systems tailored for different wafer processes, such as grinding, etching, and polishing, and employs techniques like white interference microscopy, confocal microscopy, and photometric stereo.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical projection measurement method is used, then measurement can be performed, but measurement precision is insufficient due to blurring from wafer alignment, crystal orientation, and light diffraction
Solution Approach 1:
The patent changes the measurement parameters by using multiple imaging methods (white interference microscopy, confocal microscopy, photometric stereo) with different angle of incidence ranges. Each imaging method is optimized for specific surface conditions and processes, allowing accurate measurement of complex notch shapes that cannot be measured accurately by a single conventional optical projection method
Solution Approach 2:
The patent segments the measurement process by dividing it into multiple imaging steps, each using a different imaging method tailored to specific surface conditions. The control device selects and switches between different imaging systems based on the wafer process (grinding, etching, polishing) and surface characteristics, thereby overcoming the limitations of any single measurement method
2Adaptability or versatility
If single imaging method is used, then device complexity is low, but adaptability to different wafer processes and surface conditions is insufficient
Solution Approach 1:
The patent implements a universal measurement system that can handle multiple wafer processes (grinding, etching, polishing) and different surface conditions through a single integrated device. The control device automatically selects the appropriate imaging method based on the process type and surface characteristics, making the system adaptable to various measurement scenarios without requiring separate dedicated devices for each process
Solution Approach 2:
The patent introduces dynamic switching capability where the control device can dynamically select and switch between different imaging systems based on real-time measurement requirements. This dynamic adaptability allows the system to optimize measurement parameters for each specific case while maintaining a unified device structure
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 accurate measurement of complex shapes, particularly notch portions, by controlling the angle of incidence and using multiple imaging systems to enhance precision and efficiency.
Implementation Method 1
an imaging system that irradiates the measurement object with parallel light and acquires the surface image
Implementation Method 2
one for acquiring white interference microscopic images
Implementation Method 3
one for acquiring confocal microscopic images
Data Source
AI summary
[Solution] A shape measurement device for acquiring a plurality of surface images while scanning a surface of a plate-shaped measurement object 1 and measuring a shape of the measurement object 1 includes: an imaging system 10 that irradiates the measurement object 1 with parallel light and acquires the surface image; a stage system 30 that holds the measurement object 1 and adjusts an attitude of the measurement object 1 with respect to the imaging system 10; and a control device 20. The control device 20 includes: an attitude adjustment unit 21 that controls the imaging system 10 and the stage system 30 to scan the surface while adjusting the attitude to obtain a plurality of surface images; and an image processing unit 22 that generates a restored model of a three-dimensional shape of the measurement object 1 from the plurality of acquired surface images. When acquiring the surface image, the attitude adjustment unit 21 adjusts the attitude so that an angle of incidence of the parallel light onto the surface falls within a predetermined range. According to the shape measurement device, it is possible to measure the shape of a plate-shaped measurement object, particularly a notch portion of a wafer having a complicated shape, with higher accuracy.