Wafer Metrology System Using Segmented Optical Detection
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Solution Overview
Problem
Current metrology tools for semiconductor manufacturing are slow and inadequate for inline monitoring, often providing insufficient information about wafer characteristics due to limited sampling, and attempts to use inspection systems for metrology-like measurements are sub-optimal, particularly for detecting spatially non-localized characteristics like surface roughness and film thickness.
Innovation Solution
A system comprising multiple detection subsystems optimized for different characteristics, including spatially localized and non-spatially localized features, which direct light to the wafer and detect scattered light to generate outputs used by a computer subsystem for determining specific characteristics such as defects and surface roughness variations across various spatial frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If metrology tools are used to measure wafer characteristics, then measurement precision is improved, but productivity deteriorates due to slow measurement speed impacting cycle time
Solution Approach 1:
The patent segments the measurement task by using multiple specialized detection subsystems (first detection subsystem for spatially localized characteristics, second detection subsystem for spatially non-localized characteristics) that can simultaneously measure different wafer characteristics. This parallel measurement approach maintains high precision while reducing total measurement time, thereby improving productivity without increasing cycle time.
2Productivity
If metrology measurements are performed at one location or limited locations on wafers, then productivity is improved by reducing measurement time, but measurement precision deteriorates due to insufficient information about wafer characteristics
Solution Approach 1:
The patent creates a universal measurement system where the first and second detection subsystems work together to provide comprehensive wafer characterization. The system can simultaneously acquire spatially localized characteristics (such as defect information) and spatially non-localized characteristics (such as surface roughness and film thickness) across the wafer, ensuring complete measurement coverage while maintaining high measurement speed for inline monitoring.
3Productivity
If inspection systems are used to determine metrology-like characteristics, then productivity is improved by using existing systems, but measurement precision deteriorates because a single collector cannot optimally detect multiple surface characteristics
Solution Approach 1:
The patent segments the detection function by providing separate specialized detection subsystems for different types of measurements. The first detection subsystem is optimized for spatially localized characteristics while the second detection subsystem is optimized for spatially non-localized characteristics. This segmentation allows each subsystem to be optimized for its specific measurement type, achieving high precision for both defect detection and surface roughness measurement simultaneously, unlike a single-collector inspection system.
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 simultaneous and detailed measurement of multiple wafer characteristics, improving the accuracy and efficiency of semiconductor manufacturing by providing comprehensive data for process monitoring and control without increasing cycle time.
Implementation Method 1
A system is disclosed including an illumination subsystem configured to direct light to a wafer; a first detection subsystem configured to detect light scattered from the wafer and to generate output responsive to the detected scattered light; and a second detection subsystem configured to detect light scattered from the wafer
Data Source
AI summary
Systems and methods for determining two or more characteristics of a wafer are provided. The two or more characteristics include a characteristic of the wafer that is spatially localized in at least one dimension and a characteristic of the wafer that is not spatially localized in two dimensions.