Overlay Error Measurement with OPE Correction
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Solution Overview
Problem
Current semiconductor measurement technologies face challenges in accurately measuring overlay errors due to the optical proximity effect (OPE), which causes pattern shifts and distortions, especially as semiconductor devices become more miniaturized, making it difficult to achieve high-accuracy overlay error measurement.
Innovation Solution
An overlay error measuring device using a charged particle beam device, such as a scanning electron microscope, to measure dimensions between patterns and correct for pattern shifts caused by the optical proximity effect, along with a computer program that selects symmetry patterns for correction, enabling accurate overlay error measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interpattern dimension measurement is performed using actually formed patterns, then measurement accuracy is improved to nano-level, but pattern shift due to optical proximity effect contaminates the measurement results
Solution Approach 1:
The invention extracts and removes the optical proximity effect component from the measured interpattern dimension data through calculation processing, separating the OPE-induced pattern shift from the actual overlay error to obtain reliable overlay measurement results
Solution Approach 2:
The invention introduces layout data (design data) as an intermediary reference to compare against actual pattern positions, enabling the calculation and extraction of OPE-induced shifts by finding the difference between designed and actual pattern locations
2Measurement precision
If optical inspection device is used for superposition measurement, then dedicated alignment marks can be measured, but lens aberration causes transfer-pattern distortions and measurement errors
Solution Approach 1:
The invention replaces optical inspection with charged particle beam inspection (such as scanning electron microscopy), substituting optical measurement with particle beam-based imaging that does not suffer from lens aberration and transfer-pattern distortion effects
Solution Approach 2:
The invention changes the fundamental measurement parameter from optical wavelength to charged particle beam properties, exploiting the different physical interaction mechanisms to avoid optical system limitations and achieve distortion-free pattern imaging
3Reliability
If measurement is performed on fine patterns in local regions, then lens aberration error can be excluded, but measurement time and complexity increase
Solution Approach 1:
The invention segments the overlay error measurement process into two distinct components: OPE-induced pattern shift and actual overlay error, enabling simultaneous measurement of both through a single interpattern dimension measurement rather than requiring multiple separate measurements
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
The solution allows for precise overlay error measurement by correcting for pattern shifts caused by the optical proximity effect, thereby achieving high-accuracy overlay error measurement and suppressing the influence of OPE, even at the nano-level, enhancing the accuracy of semiconductor device production.
Implementation Method 1
an image representing actually formed patterns is obtained by a charged particle beam device
Data Source
AI summary
The purpose of the present invention is to provide an overlay error measuring device for correcting a pattern displacement other than an overlay error to thereby achieve high-precision overlay error measurement. To accomplish the abovementioned purpose, the present invention proposes an overlay error measuring device which measures a dimension between a plurality of patterns belonging to different layers using a signal obtained by a charged particle beam device, and when measuring the dimension, corrects an amount corresponding to a pattern shift due to an optical proximity effect and measures the dimension between the plurality of patterns.