SEM Pattern Height Metrology Using Contrast Calibration
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Solution Overview
Problem
Existing e-beam systems, such as SEMs, are limited in measuring pattern height of patterns produced by EUV lithography in very thin resist films, as introducing a tilt to extract height information leads to loss of resolution and inability to measure small features.
Innovation Solution
A device and method using a processor to obtain SEM images, determine a contrast value based on the image, and calculate pattern height using calibration data, allowing accurate measurement of pattern height without requiring a tilt of the electron beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tilt is introduced in the e-beam system to extract height information, then pattern height measurement capability is improved, but resolution is lost and the system becomes unable to measure very small features
Solution Approach 1:
The patent changes the measurement parameter from direct height extraction via tilt to contrast value measurement at normal incidence. By measuring the contrast value (intensity difference) between patterned and unpatterned areas in SEM images and correlating it with pattern height through calibration, the system maintains normal beam incidence (preserving resolution) while achieving height measurement capability.
2Manufacturing precision
If EUV lithography is used to produce patterns with smaller CD, then lithographic patterning performance is improved, but the depth of field scales down requiring thinner resist films
Solution Approach 1:
The patent transitions from direct vertical height measurement (which fails in thin films with tilt) to a two-dimensional contrast value measurement in the image plane. By measuring intensity variations across the patterned and unpatterned areas in the lateral dimension and correlating with height, the method enables height measurement in ultrathin resist films without requiring beam tilt or additional vertical dimension access.
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 and effective measurement of pattern height in EUV-produced patterns, even in very thin resist films, maintaining resolution and allowing measurement of small features.
Implementation Method 1
obtain a SEM image of the pattern from an SEM
Data Source
AI summary
The present disclosure relates to the determination of a pattern height of a pattern, which has been produced with extreme ultraviolet (EUV) lithography in a resist film. The determination is performed by using an electron beam (e-beam) system, in particular, by using a scanning electron microscope (SEM). In this respect, the disclosure provides a device for determining the pattern height, wherein the device comprising a processor. The processor is configured to obtain a SEM image of the pattern from an SEM. Further, the processor is configured to determine a contrast value related to the pattern based on the obtained SEM image. Subsequently, the processor is configured to determine the pattern height based on calibration data and the determined contrast value.