Wafer Edge Pre-Aligning Element Detection via Dual Illumination
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Solution Overview
Problem
Semiconductor wafer alignment systems face challenges in reliably detecting pre-aligning elements due to adhesive residuals, which cause errors and lead to the rejection or discarding of wafers, resulting in increased costs and reduced success rates.
Innovation Solution
An apparatus comprising a sensor arrangement and evaluation unit that illuminates the wafer edge, outputs sensor signals based on transmitted and reflected illumination, and determines both coarse and fine positions of the pre-aligning element, effectively overcoming adhesive-related errors by combining transmitted and reflected signal evaluations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If transmitted illumination is used to detect pre-aligning elements, then detection speed is improved, but detection reliability deteriorates due to adhesive residuals blocking light
Solution Approach 1:
The patent combines transmitted illumination and reflected illumination detection methods into a single pre-alignment system. The transmitted light path provides fast detection speed while the reflected light path compensates for reliability issues caused by adhesive residuals, achieving both high speed and high reliability simultaneously
Solution Approach 2:
The reflected illumination acts as an intermediary detection method that bypasses the adhesive residual problem. When transmitted light detection is compromised by adhesive blocking, the reflected light detection provides an alternative path to reliably detect pre-aligning elements without being affected by the same interference
2Reliability
If reflected illumination is used to detect pre-aligning elements, then detection reliability is improved, but detection precision deteriorates due to manufacturing grooves causing false signals
Solution Approach 1:
The system uses feedback from both transmitted and reflected illumination detection to verify and correct position measurements. The transmitted light provides precise position information while the reflected light provides reliability verification, allowing the system to distinguish true pre-aligning elements from false signals caused by manufacturing grooves
Solution Approach 2:
The transmitted illumination detection is performed first to establish a preliminary precise position measurement. This preliminary action provides a reference that helps distinguish true pre-aligning elements from false signals detected by the reflected illumination, thereby maintaining measurement precision while improving reliability
3Device complexity
If only transmitted illumination is used, then device complexity is reduced, but detection reliability deteriorates due to adhesive residuals
Solution Approach 1:
The patent merges transmitted illumination and reflected illumination detection systems into a unified pre-alignment apparatus. Although this increases device complexity slightly, it dramatically improves detection reliability by providing complementary detection paths that compensate for each other's weaknesses, particularly in overcoming adhesive residual interference
4Reliability
If only reflected illumination is used, then detection reliability is improved, but manufacturing precision requirements increase due to sensitivity to surface grooves
Solution Approach 1:
The transmitted illumination detection provides feedback that is less sensitive to surface grooves and manufacturing variations. This feedback mechanism allows the system to maintain high detection reliability while reducing the stringency of manufacturing precision requirements, as the transmitted light path serves as a more robust reference
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 enhances the accuracy and reliability of wafer alignment by providing precise positioning of pre-aligning elements, reducing the impact of adhesive residuals and manufacturing grooves, thereby improving the success rate of wafer processing and reducing waste.
Implementation Method 1
to receive transmitted fractions and reflected fractions of the illumination from the illuminated edge portions
Implementation Method 2
to receive transmitted fractions and reflected fractions of the illumination from the illuminated edge portions
Data Source
AI summary
An apparatus for detecting a pre-aligning element at a wafer and a method for pre-aligning a wafer are disclosed. In an embodiment, the apparatus includes a sensor arrangement configured to illuminate subsequent edge portions of the wafer edge and to output a first and a second sensor signal, wherein the first sensor signal is based on the transmitted fractions of the illumination and the second sensor signal is based on the reflected fractions of the illumination; and an evaluation unit configured to evaluate the first sensor signal and to determine a first position information indicating a coarse position of the pre-aligning element, and, after having determined the first position information, to determine a second position information based on the second sensor signal and the first position information, wherein the second position information indicates a fine position of the pre-aligning element.