Semiconductor Wafer Height Measurement via Differential Light Detection
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Solution Overview
Problem
Current methods for determining the height of semiconductor structures, such as photolithography systems, face challenges in precision and throughput, particularly in mid-end-of-line and back-end-of-line applications, where feature variations can lead to device malfunction and yield issues.
Innovation Solution
A system utilizing differential detectors positioned before and after the focal point to detect light intensity variations, allowing for accurate height determination without additional measurements, incorporating illumination modules with pinholes or slits and processors to calculate height based on detected light intensities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional height measurement methods (triangulation, confocal microscopy, white-light interferometry) are used, then height can be determined, but measurement precision and throughput are insufficient for modern semiconductor manufacturing requirements
Solution Approach 1:
The detection system is segmented into multiple detectors positioned at different locations in the focal plane. Each detector captures light intensity from specific depth ranges, allowing simultaneous measurement of multiple height levels. This segmentation enables parallel processing of height information, improving both precision and throughput.
Solution Approach 2:
The invention transitions from traditional single-point or scanning measurement approaches to a multi-dimensional detection scheme. By positioning detectors at different spatial locations in the focal plane, the system captures height information across multiple dimensions simultaneously, enabling high-speed parallel measurement without sacrificing precision.
2Measurement precision
If additional measurements are taken to improve height determination accuracy, then precision improves, but measurement time increases and throughput decreases
Solution Approach 1:
The system performs preliminary positioning of multiple detectors at optimal locations in the focal plane before measurement begins. This preliminary configuration allows the system to capture complete height information in a single measurement event, eliminating the need for repeated measurements and reducing measurement time while maintaining high accuracy.
Solution Approach 2:
The multi-detector system continuously captures height information from different depth levels simultaneously in a single continuous measurement process. This eliminates the intermittent nature of sequential measurements, maintaining continuous useful action and significantly reducing total measurement time while preserving precision.
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 enables high-accuracy, high-speed height determination on semiconductor wafers, overcoming the limitations of existing techniques like triangulation, confocal microscopy, and white-light interferometry in terms of precision and throughput.
Implementation Method 1
a collection module for detecting light reflected from the surfaces
Data Source
Figure 1A~1B
Figure 1C
Figure 1D
AI summary
Disclosed are apparatus and methods for determining height of a semiconductor structure. The system includes an illumination module for directing one or more source lines or points towards a specimen having multiple surfaces at different relative heights and a collection module for detecting light reflected from the surfaces. The collection module contains at least two detectors with one slit or pinhole in front of each detector that that are positioned to receive light reflected from one of the surfaces. A first detector receives reflected light from a slit or pinhole that is positioned before a focal point, and a second detector receive reflected light from a slit or pinhole that is positioned after the focal point so that the first and second detector receive light having different intensity values unless the surface is at an optimum focus. The system includes a processor system for determining a height based on the detected light received by the detectors from two of the surfaces.