Time-Domain Optical Metrology for Semiconductor Layer Separation
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Solution Overview
Problem
Existing optical scatterometry techniques struggle to characterize semiconductor devices with both periodic and aperiodic patterned structures due to their inability to distinguish between upper and lower layers effectively.
Innovation Solution
Creating a time-domain representation of wavelength-domain measurement data, selecting an earlier-in-time portion that excludes a later-in-time portion, and using model-based processing to determine parameters of interest for upper layers, excluding other layers, thereby enhancing characterization of semiconductor devices with mixed periodic and aperiodic structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If optical scatterometry is used to characterize semiconductor devices with both periodic and aperiodic structures, then measurement capability is improved, but layer differentiation capability deteriorates
Solution Approach 1:
The patent segments the time-domain representation of the optical signal into multiple portions based on time-of-flight. By dividing the measurement data into early-time and late-time portions, the system can selectively analyze reflections from different layer depths. This segmentation enables precise differentiation between upper periodic layers and lower aperiodic layers, resolving the layer differentiation problem while maintaining measurement versatility.
Solution Approach 2:
The patent transforms the traditional wavelength-domain optical measurement into the time-domain representation. This dimensional transformation from frequency domain to time domain introduces a new dimension (time-of-flight) that provides depth information about reflected light. This additional dimensional information enables the system to distinguish between layers at different depths, thereby improving layer differentiation capability while maintaining adaptability to various device structures.
2Measurement precision
If time-domain representation is created using both spectral amplitude and spectral phase, then measurement accuracy is improved, but data processing complexity increases
Solution Approach 1:
The patent extracts and utilizes both spectral amplitude and spectral phase information from the optical measurement data when creating the time-domain representation. By taking out and processing both components separately and then combining them, the system achieves higher measurement accuracy. The systematic extraction and processing of these two components, while increasing processing steps, provides comprehensive information for precise layer characterization.
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 accurate measurement of upper layer properties in semiconductor devices with mixed periodic and aperiodic structures, improving metrology and inspection capabilities.
Implementation Method 1
measuring light reflected by the various layers of a semiconductor device
Implementation Method 2
creating a time-domain representation of wavelength-domain measurement data
Data Source
AI summary
Semiconductor device metrology including creating a time-domain representation of wavelength-domain measurement data of light reflected by a patterned structure of a semiconductor device, selecting an earlier-in-time portion of the time-domain representation that excludes a later-in-time portion of the time-domain representation, and determining one or more measurements of one or more parameters of interest of the patterned structure by performing model-based processing using the earlier-in-time portion of the time-domain representation.