Optical Device Noise Filter for Semiconductor Measurement
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Solution Overview
Problem
In semiconductor device manufacturing, conventional optical measurement techniques face challenges in accurately measuring three-dimensional structure dimensions due to noise from underlying layers, which reduces measurement sensitivity and accuracy, especially as pattern miniaturization increases and distances between stacked patterns shorten.
Innovation Solution
An optical device is designed with a noise filter, including a pinhole plate, to remove reflected light from underlying layers, allowing only the signal from the measurement target layer to be detected, thereby enhancing measurement sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical measurement is performed on three-dimensional structures, then measurement speed is maintained, but measurement accuracy deteriorates due to signal mixing from underlying layers
Solution Approach 1:
The optical measurement process is segmented into multiple wavelength measurements. By measuring at different wavelengths and selectively combining results, the system isolates signals from the target layer while excluding signals from underlying layers, thereby eliminating signal mixing noise and improving measurement accuracy
Solution Approach 2:
A computational algorithm acts as an intermediary between the raw optical signals and the final measurement result. The algorithm processes multi-wavelength reflectance data to distinguish target layer signals from underlying layer signals, effectively filtering out noise and enhancing measurement precision
2Measurement precision
If the distance between stacked patterns is reduced for device miniaturization, then device density increases, but measurement sensitivity deteriorates due to increased signal mixing
Solution Approach 1:
The measurement is segmented into wavelength-specific components. By analyzing reflectance at multiple wavelengths and selectively combining measurements based on optical path differences, the system can resolve signals from closely spaced patterns, maintaining measurement sensitivity even when pattern distances are reduced for device miniaturization
3Measurement precision
If underlying layer signals are included in the measurement, then the optical system remains simple, but measurement accuracy deteriorates due to noise from out-of-focus layers
Solution Approach 1:
The system changes the wavelength parameter of the measurement process. By performing measurements at multiple wavelengths and selectively combining results based on optical path difference criteria, the system achieves high measurement accuracy without requiring complex optical filtering mechanisms, thus avoiding increased device complexity
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 optical device effectively filters out noise from underlying layers, improving the measurement accuracy and sensitivity of three-dimensional structure dimensions in semiconductor devices by isolating the signal from the measurement target layer.
Implementation Method 1
a noise filter on a path of the reflected light between the image sensor and the objective lens, wherein the noise filter may be configured to remove a part of the reflected light generated by underlying layers below a measurement target layer of the sample among the reflected light
Implementation Method 2
a first lens arranged on the path of the input light passing through the pinhole plate and configured to collimate the input light so that the input light becomes a parallel light
Data Source
AI summary
An optical device is provided. The optical device includes: a light source; a pinhole plate arranged on a path of input light between the light source and an objective lens; an image sensor configured to detect a reflected light generated by the input light being reflected by a sample; and a noise filter arranged on the path of the reflected light between the image sensor and the objective lens, and the noise filter may remove a part of the reflected light generated by underlying layers below a measurement target layer of the sample.