Single CCD Color TDI Autofocus for Wafer Positioning
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Solution Overview
Problem
Existing autofocus systems in semiconductor processing are slow, complex, and expensive, and achieve suboptimal results in measuring the position of wafers with high accuracy.
Innovation Solution
A chromatic, time-domain integration (TDI) charge-coupled device (CCD) detector is used with a fringe projection type autofocus system, capable of capturing multiple color images simultaneously by synchronizing light sources with charge transfer, allowing for precise positioning of wafers using a single detector that measures different spectral properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional autofocus systems are used, then measurement capability is provided, but the systems are slow, complex, and expensive with suboptimal accuracy
Solution Approach 1:
The patent combines multiple measurement capabilities into a single detector by integrating multiple pixel arrays with different spectral sensitivities (e.g., blue, green, red sensitive pixels) onto one detector substrate. This merging eliminates the need for multiple separate detectors and complex optical paths, thereby reducing device complexity while maintaining or improving measurement precision through multi-wavelength autofocus capability
Solution Approach 2:
The single detector is designed to perform multiple functions simultaneously by incorporating pixel arrays with different spectral responses. Each pixel array can detect different wavelengths of light, enabling the detector to measure autofocus information across multiple spectral bands without requiring separate dedicated detectors for each wavelength, thus achieving multi-functionality with reduced complexity
2Measurement precision
If traditional autofocus systems are used, then measurement capability is provided, but the systems are slow and achieve suboptimal results
Solution Approach 1:
By merging multiple pixel arrays with different spectral sensitivities into a single detector, the system can simultaneously capture autofocus information across multiple wavelengths in one measurement cycle. This eliminates the need for sequential measurements with separate detectors, thereby increasing productivity while maintaining high measurement precision through multi-spectral data acquisition
3Measurement precision
If multiple detectors are used to measure different spectral properties, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple pixel arrays designed to detect different spectral properties (blue, green, red sensitive pixels) onto a single detector substrate. This integration maintains the spectral measurement precision of multiple detectors while eliminating the complexity associated with multiple separate detector systems, including simplified optical paths, reduced alignment requirements, and lower overall system cost
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
The solution provides faster, simpler, and less expensive autofocus systems with improved accuracy for wafer positioning, enabling the manufacture of higher density wafers with reduced errors and increased efficiency.
Implementation Method 1
a charge is generated from the light impinging on the first active column of pixels, is transferred to the first masked column of pixels, and subsequently is transferred to the second active column of pixels
Implementation Method 2
a charge is generated from the light impinging on the first active column of pixels
Data Source
AI summary
A detector (550) for detecting light (248B) from a light source (248A) comprises a single array of pixels (574) and a first mask (576). The single array of pixels (574) includes a plurality of rows of pixels (574R), and a plurality of columns of pixels (574C) having at least a first active column of pixels (574AC) and a spaced apart second active column of pixels (574AC). The first mask (576) covers one of the plurality of columns of pixels (574C) to provide a first masked column of pixels (574MC) that is positioned between the first active column of pixels (574AC) and the second active column of pixels (574AC). Additionally, a charge is generated from the light (248B) impinging on the first active column of pixels (574AC), is transferred to the first masked column of pixels (574MC), and subsequently is transferred to the second active column of pixels (574AC).