Pupil Image Pattern Uniformity Measurement for Semiconductor Masks
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Solution Overview
Problem
In semiconductor manufacturing, the reduction in pattern sizes poses a challenge for measurement accuracy due to resolution issues in existing measurement apparatuses, particularly in measuring pattern uniformity on wafers or masks, where methods like short wavelength and high numerical aperture have limitations such as insufficient light and physical constraints.
Innovation Solution
A measurement apparatus and method utilizing a pupil image to detect zero-order and 1st-order light, with a small-sized detector and advanced illumination unit, enabling precise measurement of pattern uniformity by selecting only the array area and correcting for light fluctuations, thereby enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If short wavelength is implemented to enhance optical resolution, then measurement precision is improved, but light intensity becomes insufficient
Solution Approach 1:
The patent changes the parameter of wavelength to a shorter range (extreme ultraviolet band, 10-20nm) to improve resolution, while compensating for light intensity loss through enhanced optical system design and detection sensitivity improvements
2Measurement precision
If high numerical aperture is implemented to enhance optical resolution, then measurement precision is improved, but device complexity increases due to physical limitations of objective lens size
Solution Approach 1:
The patent increases the numerical aperture parameter to enhance resolution capability, while managing the physical constraints through optimized optical path design and compact arrangement of optical components
3Manufacturing precision
If pattern size is reduced to meet design rules, then manufacturing precision is improved, but measurement precision deteriorates due to resolution issues
Solution Approach 1:
The patent reduces pattern dimensions to meet design rules while implementing corresponding improvements in optical resolution parameters (shorter wavelength, higher numerical aperture) to ensure measurement precision is maintained or improved despite smaller feature sizes
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 effectively measures pattern uniformity with high accuracy by using a small detector size and advanced illumination, reducing noise and improving measurement precision, even with miniaturized patterns, while also reducing detection time through focus mapping and sampling.
Implementation Method 1
a light source configured to generate and output light, an optical system configured to transfer the light, output from the light source, to the measurement target
Implementation Method 2
a first detector configured to detect light reflected and diffracted by the measurement target, or to detect light diffracted by passing through the measurement target
Data Source
AI summary
An apparatus and method of measuring pattern uniformity, and a method of manufacturing a mask by using the measurement method are provided. The measurement apparatus includes a light source configured to generate and output light, a stage configured to support a measurement target, an optical system configured to transfer the light, output from the light source, to the measurement target supported on the stage, and a first detector configured to detect light reflected and diffracted by the measurement target, or diffracted by passing through the measurement target, wherein the first detector is configured to detect a pupil image of a pupil plane and to measure pattern uniformity of an array area of the measurement target on the basis of intensity of at least one of zero-order light and 1st-order light of the pupil image.