Time-Domain Optical Metrology for Semiconductor Layer Isolation
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Solution Overview
Problem
Existing optical scatterometry techniques struggle to characterize semiconductor devices with both periodic and aperiodic patterned structures, as they are sensitive to all layers in the stack, making it difficult to separate and measure properties of upper and lower layers accurately, especially in complex structures like logic and memory devices.
Innovation Solution
The implementation of time-domain optical metrology systems that create a time-domain representation of wavelength-domain measurement data, allowing for the selection of specific portions of the data to isolate measurements from upper layers, reducing sensitivity to underlayers and enabling more precise parameter determination and structural anomaly detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical scatterometry is used to measure light reflected by all layers of a semiconductor device, then comprehensive characterization data is obtained, but it becomes difficult to separate and accurately measure properties of upper and lower layers independently
Solution Approach 1:
The patent segments the optical measurement data by transforming wavelength-domain spectra into time-domain representations, where different layers appear at different time points. This allows selective analysis of specific layers (upper or lower) by focusing on particular time windows, effectively dividing the complex multi-layer measurement problem into separable layer-specific measurements.
Solution Approach 2:
The patent transitions from wavelength-domain analysis to time-domain analysis, adding a temporal dimension to the measurement data. This dimensional transformation enables discrimination between layers that appear mixed in the wavelength domain, as each layer's optical response arrives at different times in the time-domain representation.
2Adaptability or versatility
If existing optical scatterometry techniques are applied to devices with both periodic and aperiodic structures, then measurement of periodic structures is achieved, but characterization of aperiodic structures becomes difficult or impossible
Solution Approach 1:
The patent creates a universal measurement approach that works for both periodic and aperiodic structures by using time-domain analysis. Unlike traditional scatterometry that relies on periodicity assumptions, the time-domain method can handle any structural pattern, making the technique universally applicable to mixed periodic-aperiodic semiconductor devices while maintaining measurement 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 enhances the ability to measure semiconductor devices by reducing sensitivity to irrelevant layers, improving vertical resolution, and allowing for more accurate characterization of complex structures, including those with non-periodic underlayers, thereby facilitating more robust and flexible metrology solutions.
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
A method for semiconductor device metrology. The method may include creating a time-domain representation of wavelength-domain measurement data of light reflected by a three dimensional (3D) patterned structure of a semiconductor device; selecting one or more relevant peaks of the time-domain representation and at least one irrelevant portion of the time-domain representation. One or more relevant peaks occur during one or more relevant time periods; and are associated with corresponding relevant reference peaks that are associated with different versions of a reference 3D patterned structure.