Semiconductor Surface Topography Metrology Using Interference Signal Calibration
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Solution Overview
Problem
Current methods for semiconductor chip surface topography metrology, such as atomic force microscopy (AFM) and electron microscopy, face limitations in throughput, accuracy, and precision, particularly in measuring the topography of wafers with multiple layers, leading to inefficiencies in semiconductor manufacturing.
Innovation Solution
The implementation of a system that uses interference signals and spectrum signals, combined with machine learning models, to classify and calibrate surface height offsets, enabling high-throughput inline measurement of semiconductor chip surface topography without the need for opaque film deposition or wafer consumption, and extending the light source spectrum to improve signal-to-noise ratio and repeatability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If atomic force microscopy (AFM) or electron microscopy is used to measure surface topography, then measurement precision is improved, but productivity deteriorates due to low throughput
Solution Approach 1:
The patent replaces mechanical contact-based measurement systems (AFM) with optical interferometry-based measurement systems. The optical system uses light interference patterns to measure surface topography without physical contact, enabling non-contact, high-speed scanning that dramatically increases throughput while maintaining measurement precision through sophisticated interferometric algorithms and signal processing.
Solution Approach 2:
The patent changes the measurement parameters by using optical wavelength-scale resolution instead of mechanical probe resolution. By utilizing the wave nature of light and interferometric techniques, the system achieves nanometer-scale vertical resolution and micrometer-scale lateral resolution, enabling fast scanning speeds that improve productivity while maintaining the precision required for semiconductor wafer bonding applications.
2Productivity
If conventional interferometry is used for measurement, then productivity is improved through faster scanning, but measurement precision deteriorates due to inability to distinguish multiple layers
Solution Approach 1:
The patent segments the complex interference signal into multiple wavelength components. By using multi-wavelength or broadband light sources and analyzing the interference patterns at different wavelengths, the system can distinguish between reflections from different depths (multiple layers) within the wafer structure. This segmentation of the optical spectrum enables precise depth resolution while maintaining high scanning speeds.
Solution Approach 2:
The patent adds the spectral dimension to the spatial measurement. Instead of relying solely on spatial scanning, the system incorporates spectral analysis by measuring interference patterns across multiple wavelengths. This additional dimensional information allows the system to resolve depth ambiguities and distinguish multiple reflective interfaces within the wafer, achieving precise surface height measurement even at high scanning speeds.
3Measurement precision
If light source spectrum is extended to improve signal-to-noise ratio, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent designs the optical system with multi-functionality, where a single broadband or tunable light source serves multiple purposes: providing the extended spectrum for improved signal-to-noise ratio, enabling multi-wavelength interferometry for depth resolution, and allowing flexibility in adjusting the spectral content based on specific measurement requirements. This universal light source approach improves measurement precision while avoiding the need for multiple specialized light sources, thereby limiting the increase in device complexity.
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 approach allows for accurate and precise measurement of semiconductor chip surface topography, enhancing manufacturing efficiency and reducing yield loss by providing calibrated height maps with improved accuracy and precision.
Implementation Method 1
A plurality of interference signals each corresponding to a respective one of a plurality of positions on a surface of the semiconductor chip are received by at least one processor
Data Source
AI summary
Embodiments of systems and methods for measuring a surface topography of a semiconductor structure are disclosed. In certain examples, a plurality of interference signals, each corresponding to a respective one of a plurality of positions on a surface of the semiconductor structure, are measured. Calibration signals, associated with a baseline region corresponding to a first category of a plurality of categories and a calibrated region corresponding to a second category of the plurality of categories, are measured. A surface height offset, associated with the baseline region and the calibrated region, is determined based on original surface heights and the calibration signals. The original surface heights are determined based on the plurality of interference signals corresponding to the baseline region and the calibrated region. The surface topography of the semiconductor structure is characterized based, at least in part, on the surface height offset and the original surface heights.